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Skin and nail

Chilblains

Last revised in March 2025

Chilblains (also known as perniosis or pernio) are localized inflammatory skin lesions on exposed extremities of the body, precipitated by cold.

Chilblains: Summary

  • Chilblains (also known as perniosis) are localized cold-induced inflammatory lesions, which affect areas of skin vulnerable to cold exposure such as the fingers, toes, nose, and ears.
  • Chilblains can be classified as acute or chronic:
    • Acute chilblains develop within 12–24 hours of exposure to cold and usually resolve within 2–3 weeks, provided that further cold exposure is avoided. 
    • Chronic chilblains are persistent lesions which can develop on repeated exposure to cold — in some cases leading to scarring and atrophy.
  • Chilblains are thought to be caused by prolonged or intermittent cold-induced vasoconstriction of deep cutaneous arterioles with associated dilatation of smaller superficial vessels, in susceptible people.
    • Primary or idiopathic chilblains are not associated with any underlying condition.
    • Secondary chilblains are associated with underlying conditions such as connective tissue or haematological disorders.
  • Risk factors for chilblains include:
    • Family history.
    • Peripheral vascular disease.
    • Low body weight or poor nutrition.
  • Complications include:
    • Skin excoriation from scratching.
    • Secondary infection from blistered or scratched chilblains.
    • Ulceration.
    • Permanent discolouration.
    • Scarring.
  • Chilblains are usually diagnosed clinically and should be suspected in people with a history of recent (within 12–24 hours) cold exposure and red–purple macular, papular or nodular lesions on acral skin (most commonly the fingers and toes).
    • Lesions are typically associated with pruritus and/or burning discomfort but may be asymptomatic.
    • Arterial circulation and peripheral sensation should be normal.
    • Further investigations/referral to an appropriate specialist is required if an underlying cause is suspected or the diagnosis is in doubt.
  • People with idiopathic chilblains should be reassured that the condition is self limiting, caused by exposure to cold, and will resolve if further exposure to cold is avoided.
  • The following should be advised:
    • Drying and gradually warming the skin — application of direct heat should be avoided.
    • Avoidance of smoking, if relevant.
    • Avoidance of cold, damp conditions (if possible) to prevent recurrence.
    • Wearing adequate clothing including warm gloves and socks.
  • Drug treatment should not be routinely prescribed, but may be considered for severe chronic chilblains and recurrent episodes of severe chilblains that do not respond to appropriate self-care measures.
    • Modified-release nifedipine (off-label indication) is an option but current evidence is based on small trials with conflicting results.

Have I got the right topic?

From age 1 month onwards.

This CKS topic covers the primary care management of chilblains.

There is a separate CKS topic on Raynaud's phenomenon.

The target audience for this CKS topic is healthcare professionals working within the NHS in the UK, and providing first contact or primary healthcare.

CKS gratefully acknowledges the contribution of the British Association of Dermatologists in the initial development of this topic.

How up-to-date is this topic?

Changes

March 2025 — minor update. Depression has been added as an adverse effect of unknown frequency of nifedipine in line with the manufacturer's instructions.

Previous changes

July 2023 — reviewed. A literature search was conducted in July 2023 to identify evidence-based guidelines, UK policy, systematic reviews, and key randomized controlled trials published since the last revision of the topic. No major changes to recommendations have been made.

April 2023 — minor update. Added juvenile spring eruption as a differential diagnosis. 

June 2018 — reviewed. A literature search was conducted in May 2018 to identify evidence-based guidelines, UK policy, systematic reviews, and key randomized controlled trials published since the last revision of this topic. No major changes to recommendations have been made.

August 2013 — reviewed. A literature search was conducted in July 2013 to identify evidence-based guidelines, UK policy, systematic reviews, and key RCTs published since the last revision of this topic. No major changes to recommendations have been made.

July to November 2009 — this is a new CKS topic. The evidence-base has been reviewed in detail, and recommendations are clearly justified and transparently linked to the supporting evidence.

Update

New evidence

Evidence-based guidelines

No new evidence-based guidelines since 1 July 2023.

HTAs (Health Technology Assessments)

No new HTAs since 1 July 2023

Economic appraisals

No new economic appraisals relevant to England since 1 July 2023.

Systematic reviews and meta-analyses

No new systematic review or meta-analysis since 1 July 2023.

Primary evidence

No new primary evidence which reaches the CKS threshold for inclusion published since 1 July 2023.

New policies

No new national policies or guidelines since 1 July 2023.

New safety alerts

No new safety alerts since 1July 2023.

Changes in product availability

No changes in product availability since 1 July 2023.

Goals and outcome measures

Goals

To support primary healthcare professionals to:

  • Identify chilblains and consider the possibility of an underlying associated condition.
  • Refer to secondary care for further assessment and management where appropriate.
  • Advise self-care measures for the management and prevention of chilblains.
  • Consider drug treatment for severe or recurrent chilblains.

Outcome measures

No outcome measures were found during the review of this topic.

Audit criteria

No audit criteria were found during the review of this topic.

QOF indicators

No QOF indicators were found during the review of this topic.

QIPP - Options for local implementation

No QIPP indicators were found during the review of this topic.

NICE quality standards

No NICE quality standards were found during the review of this topic.

Background information

What is it?

  • Chilblains (also known as perniosis) are localized cold-induced inflammatory lesions which affect areas of skin vulnerable to cold exposure, such as the fingers, toes, nose, and ears.
    • Lesions appear as oedematous, red-purple papules, plaques or nodules, which may be painful or itchy.
    • Equestrian perniosis is a less common form of perniosis which typically occurs on the thighs or buttocks of horse riders who ride for prolonged periods in cold temperatures.
  • Chilblains can be classified as:
    • Primary or secondary
      • Primary or idiopathic chilblains are not associated with any underlying condition.
      • Secondary chilblains are associated with underlying conditions such as connective tissue or haematological disorders.
    • Acute or chronic
      • Acute chilblains develop within 12–24 hours of exposure to cold and usually resolve within 2–3 weeks, provided that further cold exposure is avoided.
      • Chronic chilblains can develop in susceptible people with repeated cold exposure, leading to persistent lesions, which can result in scarring and atrophy.

[Cappel, 2014; Dane, 2015; Bashir, 2016; Souwer, 2016; Souwer, 2017; DermNet, 2021; PCDS, 2021; Dubey, 2022]

What causes it?

  • Chilblains are thought to be caused by prolonged or intermittent cold-induced vasoconstriction of deep cutaneous arterioles with associated dilatation of smaller superficial vessels.
  • Chilblains are often idiopathic but may be secondary to an underlying systemic condition such as:
    • Connective tissue disorders, in particular lupus erythematosus.
    • Haematological conditions, including malignancy, cryoglobulinaemia, and antiphospholipid syndrome.
  • Risk factors for chilblains include:
    • Smoking.
    • Outdoor occupation.
    • Family history — several members of the same family can be affected, a case-control study has suggested a familial relative risk of 3.6.
    • Peripheral vascular disease.
    • Low body weight or poor nutrition including anorexia nervosa.

[Cappel, 2014; Bashir, 2016; DermNet, 2021; PCDS, 2021; Pratt, 2021]

How common is it?

  • CKS identified no reliable data on the prevalence of chilblains in the UK.
    • Unpublished data from a Dutch General Practice database (the Continuous Morbidity Registration Nijmegen) suggests that the average Dutch General Practitioner sees 4 cases of chilblains per year [Souwer, 2011].
  • Chilblains occur in the autumn and winter months in cold, damp environments.
  • Chilblains can affect people of all ages but are most common in young to middle-aged adults. Childhood chilblains are uncommon.
  • Chilblains can occur in both sexes but are most commonly seen in females.
    • A US case review (n = 104) found that 79% of cases were female. The mean age of diagnosis was 38.3 years (range 6-80 years) [Cappel, 2014].
  • A small study of people attending a dermatology clinic for chilblains found that 86% were diagnosed with primary chilblains, with the remainder being secondary to another condition [Tacki, 2012].

 [Baker, 2016; Bashir, 2016; Saenz Ibarra, 2018; DermNet, 2021; PCDS, 2021]

What are the complications?

  • Complications of chilblains include:
    • Skin excoriation from scratching.
    • Secondary infection from blistered or scratched chilblains.
    • Ulceration.
    • Tissue necrosis.
    • Scarring.

[DermNet, 2021; Dubey, 2022; Whitman, 2022]

What is the prognosis?

  • The prognosis depends on whether chilblains are idiopathic or have an underlying cause.
    • Idiopathic chilblains are usually self-limiting and resolve within a few days to a few weeks with avoidance of cold exposure.
      • Chilblains may recur during cold seasons or become chronic and persist over the winter months.
    • For chilblains secondary to an underlying condition such as lupus erythematosus, the prognosis is determined by effective management of the condition.

[DermNet, 2021; PCDS, 2021; Dubey, 2022; Whitman, 2022]

Diagnosis of chilblains

When should I suspect chilblains?

Suspect chilblains in a person presenting with:

  • A history of recent (within 12-24 hours) cold exposure.
  • Red–purple macular, papular or nodular lesions on acral skin, most commonly the fingers and toes. The face (nose, cheeks, and earlobes) and legs (heels, lower leg, thighs and hips) can also be affected.
    • Lesions are often symmetrical (affecting both hands or both feet).
    • Lesions may also be plaque-like or annular.
    • In severe cases, blistering and ulceration may develop.
  • Pruritus and/or burning discomfort associated with the lesions – some people may be asymptomatic.
    • Lesions may be tender to palpate.
    • The person may not be aware of the lesions developing in the cold but often reports a persistent burning or pruritic sensation once warm.

Less common presentations include:

  • Papular perniosis — small crops of chilblains on the sides of fingers often on a background of acrocyanosis.
  • Equestrian perniosis — clustered indurated, red-purple papules or plaques which may blister or ulcerate on the outer thighs (and occasionally the buttocks) of people who ride horses.
    • Lesions typically appear 24-48 hours after exposure to cold and are self-limiting. Occasionally post-inflammatory hyperpigmentation, atrophy or scarring can be present after chilblains resolve.
  • Severe chronic perniosis — irreversible changes including fibrosis, lymphoedema and hyperkeratosis may develop.
    • Signs of severe chronic chilblains are more likely to be present when there is a background of arterial disease, prolonged cold exposure or an associated underlying condition.

Chilblains tend to resolve spontaneously after 2-3 weeks — in some people, they may persist throughout winter and occasionally into summer.

  • Symptoms may persist if there is continued exposure to cold, for example, associated with working conditions such as cold storage work.

Basis for recommendation

These recommendations are based on the guidelines Chilblains [PCDS, 2021] and Chilblains [DermNet, 2021], information in Rook’s Textbook of Dermatology [Bashir, 2016], Pernio [Whitman, 2022], and expert opinion in Chronic chilblains [Souwer, 2011], Clinical characteristics, etiologic associations, laboratory findings, treatment, and proposal of diagnostic criteria of pernio (chilblains) in a series of 104 patients at Mayo Clinic, 2000 to 2011 [Cappel, 2014],  Chilblains in Southern California: two case reports and a review of the literature [Gordon, 2014], Equestrian perniosis: A case report and review of the literature [Dane, 2015] and Pharmacologic Treatment of Idiopathic Chilblains (Pernio): A Systematic Review [Pratt, 2021].

How should I assess a person with suspected chilblains?

Take a history, asking about:

  • Exposure to cold.
  • Symptoms including onset, distribution and progression of lesions.
  • Risk factors such as family history.
  • Previous episodes of similar lesions and persistence of symptoms outside the cold season.
  • Associated symptoms — ask about rashes, photosensitivity, arthralgia, arthritis, oral ulcers or weight loss, to help identify potential underlying causes such as connective tissue or haematological disorders.
  • Recent viral symptoms and/or contact with a person with COVID-19 (especially in children and adolescents).

Examine the person:

  • Look for clinical signs of chilblains such as red-purple macular, papular or nodular lesions on acral skin.
    • Note: secondary chilblains may be suggested by severe and persistent symptoms, ulceration and necrosis, or other significant skin changes.
  • Check peripheral pulses looking for signs of peripheral vascular disease. For further information, see the CKS topic on Peripheral arterial disease.
  • Look for signs of diabetes — check sensation in the affected extremity to exclude neuropathy. For further information, see the CKS topics on Diabetes - type 1 and Diabetes - type 2.
  • Carry out a general examination looking for signs of associated underlying conditions such as lupus erythematosus.

Consider the need for investigations:

  • Investigations are not usually required unless an underlying cause is suspected or there is no history of cold exposure.
    • If symptoms are severe or persistent, consider investigating for associated underlying conditions such as haematological malignancy, connective tissue disorders or cryoglobulinaemia.
  • If the diagnosis is in doubt, discuss with/refer to dermatology.

Basis for recommendation

These recommendations are based on the guideline Chilblainss [PCDS, 2021] and Chilblains [DermNet, 2021], as well as information in Rook’s textbook of dermatology [Bashir, 2016], Pernio [Whitman, 2022], and review articles Acute Perniosis in Elderly People: A Predictive Sign of Systemic Disease? [Guadagni, 2010], Chronic chilblains [Souwer, 2011], Clinical characteristics, etiologic associations, laboratory findings, treatment, and proposal of diagnostic criteria of pernio (chilblains) in a series of 104 patients at Mayo Clinic, 2000 to 2011 [Cappel, 2014], Chilblains in Southern California: two case reports and a review of the literature [Gordon, 2014], Equestrian perniosis: A case report and review of the literature [Dane, 2015], Assessing the effectiveness of topical betamethasone to treat chronic chilblains: a randomised clinical trial in primary care [Souwer, 2017] and Chilblains in immune-mediated inflammatory diseases: a review [Dubey, 2022].

 

What else might it be?

The differential diagnosis of chilblains is broad and depends on the stage of the disease at presentation as well as the appearance and location of the lesions. Conditions that may present with a similar clinical picture to chilblains include:

  • Connective tissue disorders in particular lupus erythematosus and sarcoidosis (lupus pernio).
    • Chilblain lupus erythematosus is a form of cutaneous lupus that presents with similar clinical features to idiopathic chilblains.
    • Suggested by persistent, violaceous plaques that are prominent over dorsal interphalangeal joints of the fingers and toes.
    • Up to 20% of people with chilblain lupus develop systemic lupus erythematosus.
  • Haematological conditions
    • Cyanotic swelling of acral digital skin (often involving the toes) has been reported in people with haematological malignancies such as myelodysplastic syndrome and chronic myelomonocytic leukaemia.
    • Cryoglobulinaemia — cryoglobulins are immunoglobulins that reversibly precipitate or gel in the cold leading to occlusion syndromes. This may present as necrotic or purpuric lesions on acral skin which have been triggered by cold exposure.
  • Raynaud's phenomenon
    • Characteristic paroxysmal and biphasic white, and later blue discolouration, after exposure to cold.
    • For further information, see the CKS topic on Raynaud's phenomenon.
  • Acrocyanosis
    • Persistent painless cyanotic or erythrocyanotic mottled duskiness of the hands (less commonly the feet and face) in the presence of normal peripheral pulses.
  • Cold contact urticaria
    • Itching and wealing of the skin within minutes of cold exposure lasting up to 1 hour.
  • Frostbite
    • Superficial frostbite (skin and subcutis) presents with erythema and initial pain followed by a sense of warmth — affected skin becomes waxy and white.
    • Deep frostbite (extends to subcutaneous tissues and may involve nerves, major vessels, muscle and bone) can result in joint immobility and paralysis.
  • Cold panniculitis
    • Panniculitis (inflammation of the subcutaneous fat), caused by cold exposure.
    • Infants are particularly susceptible to cold panniculitis but it may also occur in adults, typically obese females.
  • Livedo reticularis
    • Mottled, cyanotic discolouration of the skin with a characteristic network pattern — accentuated by cold.
  • Vascular or neuropathic conditions
    • Peripheral vascular disease, diabetes mellitus (diabetic foot), and vasculitis may present with skin changes similar to chilblains.
  • Granuloma annulare
    • Typically presents as annular indurated papules and/or plaques on the extremities which slowly enlarge before eventually flattening and fading over months or years.
  • Juvenile spring eruption
    • Juvenile spring eruption is a variant of polymorphic light eruption. It is a photodermatosis which causes tiny blisters on the rim of the external pinna causing itch and/or discomfort.
  • 'COVID toes'
    • Presents as chilblain-like changes on the toes in people with no recent history of cold exposure.
    • Mainly seen in children and young adults.
    • Has been observed after suspected/confirmed COVID-19 infection or contact with an infected person. However, COVID-19 has not been unequivocally confirmed as causative and 'COVID toes' is commonly associated with a concurrent negative PCR test.

Basis for recommendation

This information is based on the guidelines Chilblains [PCDS, 2021] and Chilblains [DermNet, 2021], as well as information in Rook’s Textbook of Dermatology [Bashir, 2016] and review articles Acute Perniosis in Elderly People: A Predictive Sign of Systemic Disease? [Guadagni, 2010], Chronic chilblains [Souwer, 2011], Clinical characteristics, etiologic associations, laboratory findings, treatment, and proposal of diagnostic criteria of pernio (chilblains) in a series of 104 patients at Mayo Clinic, 2000 to 2011 [Cappel, 2014], Chilblains in immune-mediated inflammatory diseases: a review [Dubey, 2022], A Review of COVID-19 Chilblains-like Lesions and Their Differential Diagnoses [Sachdeva, 2021] and Chilblains-Like Lesions in Pediatric Patients: A Review of Their Epidemiology, Etiology, Outcomes, and Treatment [Fennell, 2022].

Management

Scenario: Management of chilblains

From age 1 month onwards.

How should I manage a person with chilblains?

  • Explain the diagnosis and provide patient information — patient information is available from:
  • If an underlying condition (such as lupus erythematosus or a haematological disorder) is suspected:
    • Arrange further investigations and/or refer to a specialist as appropriate, with urgency of the referral dependent on clinical judgement.
  • If chilblains are thought to be idiopathic:
    • Reassure the person that the condition is usually self-limiting and should resolve within 2–3 weeks.
    • Advise on self-care measures including:
      • Drying and gradually warming the skin — application of direct heat should be avoided.
      • Avoidance of smoking, if relevant — for further information, see the CKS topic on Smoking Cessation.
    • Advise on preventative measures to prevent recurrent episodes including:
      • Avoidance of cold, damp conditions if possible.
      • Wearing adequate clothing including warm gloves and socks.
      • Avoidance of exposures that may cause blood vessel constriction such as caffeine and decongestants.
    • Do not routinely offer drug treatment.
  • If chilblains are severe, chronic and do not respond to appropriate self-care measures:
    • Reassess the person and reconsider the possible underlying causes and the diagnosis.
      • If an underlying condition (such as lupus erythematosus) is suspected arrange further investigations/refer to a specialist depending on the specific clinical situation.
      • Discuss with/refer to a specialist if the diagnosis is uncertain.
    • Seek specialist advice if conservative measures fail in children or pregnant or breastfeeding women.
    • If no underlying cause can be identified and there are no contraindications, consider prescribing modified-release nifedipine 20-60mg daily (off-label indication).
      • Titrate slowly up to a maximum dose of 60 mg daily depending on response and tolerability.
      • Monitor the person's blood pressure as nifedipine may be associated with hypotension.
      • Discontinue treatment if not tolerated or if response is inadequate.
      • Continue treatment until the lesions have healed, or for the rest of the cold season if prophylaxis is indicated.
      • Seek specialist advice if nifedipine is unsuitable or not tolerated.
      • Do not prescribe nifedipine to children under the age of 18 years.
      • Seek specialist advice if nifedipine is being considered for pregnant or breastfeeding women.
    • Advise continuation of self-care and preventative measures in addition to drug treatment.

Basis for recommendation

This information is based on the guidelines Chilblains [PCDS, 2021] and Chilblains [DermNet, 2021], as well as information in Rook’s Textbook of Dermatology [Bashir, 2016] and review articles Chronic Chilblains [Souwer, 2011], Clinical characteristics, etiologic associations, laboratory findings, treatment, and proposal of diagnostic criteria of pernio (chilblains) in a series of 104 patients at Mayo Clinic, 2000 to 2011 [Cappel, 2014], Chilblains in immune-mediated inflammatory diseases: a review [Dubey, 2022], A Review of COVID-19 Chilblains-like Lesions and Their Differential Diagnoses [Sachdeva, 2021], Chilblains in Southern California: two case reports and a review of the literature [Gordon, 2014] and Pharmacologic Treatment of Idiopathic Chilblains (Pernio): A Systematic Review [Pratt, 2021].

Dosage of nifedipine
Pregnant or breastfeeding women
  • CKS recommends seeking specialist advice for these groups if drug treatment for chilblains is being considered.
  • Nifedipine can be used to treat hypertensive disorders of pregnancy [NICE, 2019; BNF, 2023]. However, there is no strong evidence of the efficacy of nifedipine to treat chilblains. Furthermore, while there are clear clinical benefits to both the woman and infant of treating hypertension in pregnancy, chilblains are generally self-limiting and do not usually pose a risk to overall health. CKS therefore recommends that prescribers weigh up the risks and benefits of use of nifedipine to treat chilblains in pregnant women on a case-by-case basis. The UK Teratology information service can provide patient-specific advice if required (www.uktis.org)
  • The manufacturer of nifedipine recommends avoiding during breastfeeding, although amounts excreted into breast milk are considered too low to be harmful [BNF, 2023]. Prescribers can contact the UK Drugs in Lactation Advisory Service (UKDILAS) for further information.

Prescribing information

Important aspects of prescribing information relevant to primary healthcare are covered in this section specifically for the drugs recommended in this CKS topic. For further information on contraindications, cautions, drug interactions, and adverse effects, see the electronic Medicines Compendium (eMC), or the British National Formulary (BNF).

Nifedipine

  • The use of nifedipine in the treatment and prophylaxis of chilblains is off-label, and the evidence to support its use is based on limited small studies — for more information, see the Basis for recommendation section.
  • As different versions of modified-release preparations may not have the same clinical effect, the British National Formulary recommends that prescribers specify the brand to be dispensed [BNF, 2023].

Contraindications and cautions

  • Do not prescribe nifedipine:
    • To people with known hypersensitivity to nifedipine, other dihydropyridines (theoretical risk of cross-reactivity) or any of the excipients.
    • To people with unstable angina, cardiogenic shock, significant aortic stenosis, unstable angina, or within 1 month of myocardial infarction.
    • To women who are pregnant or breastfeeding — seek specialist advice if these women require treatment.
    • To children under the age of 18 years — safety in children has not been established.
    • To people taking rifampicin. Rifampicin induces the cytochrome P450 system — bioavailability of nifedipine will be markedly reduced, the manufacturer advises to avoid.
  • Nifedipine should be prescribed with caution in:
    • People with heart failure, poor cardiac reserve, hypotension or significantly impaired left ventricular function.
    • The elderly — pharmacokinetics are altered in older people so that lower doses may be required.
    • Diabetes mellitus — may affect glycaemic control.
    • People with a history of oesophageal or gastro-intestinal obstruction, decreased lumen diameter of the gastrointestinal tract, or inflammatory bowel disease (including Crohn's disease) — some formulations should be avoided, check the individual product literature.
    • Hepatic impairment — nifedipine is metabolised primarily by the liver. Certain preparations are contraindicated in hepatic impairment.

[BNF, 2023; EMC, 2023]

Adverse effects

  • Common or very common — asthenia; dizziness; gastrointestinal disturbance (including constipation); headache; hypotension; lethargy; oedema (including peripheral oedema); palpitation; vasodilatation.
    • Short-acting formulations may be associated with large variations in blood pressure and reflex tachycardia.
  • Uncommon — angioedema; anxiety; chills; dyspnoea; dysuria; epistaxis; erectile dysfunction; hypersensitivity reactions; jaundice; joint swelling; migraine; myalgia; nasal congestion; nocturia; paraesthesia; polyuria; pruritus; rash; sleep disturbance; sweating; syncope; tachycardia; tremor; urticaria; vertigo; visual disturbance.
    • Cardiac ischaemic pain has been reported, in a small proportion of people, after taking nifedipine — discontinue treatment if this occurs.
  • Rare — anorexia; gum hyperplasia; hyperglycaemia; male infertility; mood disturbances; photosensitivity reactions; purpura.
  • Frequency not known — agranulocytosis; anaphylaxis; bezoar formation (with some modified-release preparations); dysphagia; gynaecomastia; intestinal obstruction; intestinal ulcer, depression.

[BNF, 2023; EMC, 2023; EMC, 2025]

Drug interactions

  • Nifedipine is metabolised via the cytochrome P450 3A4 system. Drugs that are known to either inhibit or to induce this enzyme system may therefore alter the first pass or the clearance of nifedipine.
    • Cytochrome P450 inhibitors (such as macrolide antibiotics [for example, erythromycin], anti-HIV protease inhibitors [for example, ritonavir], azole antimycotics [for example, ketoconazole], some antidepressants [nefazodone and fluoxetine], valproic acid, diltiazem, cimetidine and grapefruit juice) may lead to increased plasma concentrations of nifedipine.
    • Cytochrome P450 inducers (such as rifampicin [avoid], phenytoin, carbamazepine, and phenobarbital) may lead to reduced plasma concentrations of nifedipine.
  • Mefloquine — may increase the risk of bradycardia when given with nifedipine.
  • Concomitant antihypertensives — increased blood pressure lowering effect.
  • Beta-blockers — deterioration of heart failure has developed in isolated cases.
  • Digoxin — may lead to reduced digoxin clearance and an increase in the plasma digoxin level.

[EMC, 2023; BNF, 2023]

Supporting evidence

This topic is largely based on the guidelines Chilblains [PCDS, 2021] and Chilblains [DermNet, 2021], as well as information in Rook’s Textbook of Dermatology [Bashir, 2016] and review articles, Chronic chilblains [Souwer, 2011], Clinical characteristics, etiologic associations, laboratory findings, treatment, and proposal of diagnostic criteria of pernio (chilblains) in a series of 104 patients at Mayo Clinic, 2000 to 2011 [Cappel, 2014], Chilblains in Southern California: two case reports and a review of the literature [Gordon, 2014] and Pharmacologic Treatment of Idiopathic Chilblains (Pernio): A Systematic Review [Pratt, 2021]. The rationale for the primary care assessment and management of chilblains is discussed in the relevant basis for recommendation sections.

How this topic was developed

This section briefly describes the processes used in developing and updating this topic. Further details on the full process can be found in the About Us section and on the Clarity Informatics website.

Search strategy

A literature search was conducted for guidelines and systematic reviews on primary care management of chilblains.

Search dates

June 2018 - July 2023

Key search terms

Various combinations of searches were carried out. The terms listed below are the core search terms that were used for EBSCO Medline.

  • (MH "Chilblains") 
  • AB chilblain* OR TI chilblain* 
  • AB pernio* OR TI pernio* 

Sources of guidelines

Sources of systematic reviews and meta-analyses

  • The Cochrane Library:
    • Systematic reviews
    • Protocols
    • Database of Abstracts of Reviews of Effects
  • Medline (with systematic review filter)
  • EMBASE (with systematic review filter)

Sources of health technology assessments and economic appraisals

Sources of randomized controlled trials

  • The Cochrane Library:
    • Central Register of Controlled Trials
  • Medline (with randomized controlled trial filter)
  • EMBASE (with randomized controlled trial filter)

Sources of evidence based reviews and evidence summaries

Sources of national policy

Patient experiences

Sources of medicines information

The following sources are used by CKS pharmacists and are not necessarily searched by CKS information specialists for all topics. Some of these resources are not freely available and require subscriptions to access content.

Stakeholder engagement

Our policy

The external review process is an essential part of CKS topic development. Consultation with a wide range of stakeholders provides quality assurance of the topic in terms of:

  • Clinical accuracy.
  • Consistency with other providers of clinical knowledge for primary care.
  • Accuracy of implementation of national guidance (in particular NICE guidelines).
  • Usability.

Principles of the consultation process

  • The process is inclusive and any individual may participate.
  • To participate, an individual must declare whether they have any competing interests or not. If they do not declare whether or not they have competing interests, their comments will not be considered.
  • Comments received after the deadline will be considered, but they may not be acted upon before the clinical topic is issued onto the website.
  • Comments are accepted in any format that is convenient to the reviewer, although an electronic format is encouraged.
  • External reviewers are not paid for commenting on the draft topics.
  • Discussion with an individual or an organization about the CKS response to their comments is only undertaken in exceptional circumstances (at the discretion of the Clinical Editor or Editorial Steering Group).
  • All reviewers are thanked and offered a letter acknowledging their contribution for the purposes of appraisal/revalidation.
  • All reviewers are invited to be acknowledged on the website. All reviewers are given the opportunity to feedback about the external review process, enabling improvements to be made where appropriate.

Stakeholders

  • Key stakeholders identified by the CKS team are invited to comment on draft CKS topics. Individuals and organizations can also register an interest to feedback on a specific topic, or topics in a particular clinical area, through the Getting involved section of the Clarity Informatics website.
  • Stakeholders identified from the following groups are invited to review draft topics:
    • Experts in the topic area.
    • Professional organizations and societies (for example, Royal Colleges).
    • Patient organizations, Clarity has established close links with groups such as Age UK and the Alzheimer’s Society specifically for their input into new topic development, review of current topic content and advice on relevant areas of expert knowledge.
    • Guideline development groups where the topic is an implementation of a guideline.
    • The British National Formulary team.
    • The editorial team that develop MeReC Publications.
  • Reviewers are provided with clear instructions about what to review, what comments are particularly helpful, how to submit comments, and declaring interests.

Patient engagement

Clarity Informatics has enlisted the support and involvement of patients and lay persons at all stages in the process of creating the content which include:

  • Topic selection
  • Scoping of topic
  • Selection of clinical scenarios
  • First draft internal review
  • Second draft internal review
  • External review
  • Final draft and pre-publication

Our lay and patient involvement includes membership on the editorial steering group, contacting expert patient groups, organizations and individuals.

Evidence exclusion criteria

Our policy

Scoping a literature search, and reviewing the evidence for CKS is a methodical and systematic process that is carried out by the lead clinical author for each topic. Relevant evidence is gathered in order that the clinical author can make fully informed decisions and recommendations. It is important to note that some evidence may be excluded for a variety of reasons. These reasons may be applied across all CKS topics or may be specific to a given topic.

Studies identified during literature searches are reviewed to identify the most appropriate information to author a CKS topic, ensuring any recommendations are based on the best evidence. We use the principles of the GRADE and PICOT approaches to assess the quality of published research. We use the principles of AGREE II to assess the quality of published guidelines.

Standard exclusions for scoping literature:

  • Animal studies
  • Original research is not written in English

Possible exclusions for reviewed literature:

  • Sample size too small or study underpowered
  • Bias evident or promotional literature
  • Population not relevant
  • Intervention/treatment not relevant
  • Outcomes not relevant
  • Outcomes have no clear evidence of clinical effectiveness
  • Setting not relevant
  • Not relevant to UK
  • Incorrect study type
  • Review article
  • Duplicate reference

Organizational, behavioural and financial barriers

Our policy

The CKS literature searches take into consideration the following concepts, which are discussed at the initial scoping of the topic.

  • Feasibility
    • Studies are selected depending on whether the intervention under investigation is available in the NHS and can be practically and safely undertaken in primary care.
  • Organizational and Financial Impact Analysis
  • Studies are selected and evaluated on whether the intervention under investigations may have an impact on local clinical service provision or national impact on cost for the NHS. The principles of clinical budget impact analysis are adhered to, evaluated and recorded by the author. The following factors are considered when making this assessment and analysis.
    • Eligible population
    • Current interventions
    • Likely uptake of new intervention or recommendation
    • Cost of the current or new intervention mix
    • Impact on other costs
    • Condition-related costs
    • In-direct costs and service impacts
    • Time dependencies
  • Cost-effectiveness or cost-benefit analysis studies are identified where available. 

We also evaluate and include evidence from NICE accredited sources which provide economic evaluations of recommendations, such as NICE guidelines. When a recommended action may not be possible because of resource constraints, this is explicitly indicated to healthcare professionals by the wording of the CKS recommendation.

Declarations of interest

Our policy

Clarity Informatics requests that all those involved in the writing and reviewing of topics, and those involved in the external review process to declare any competing interests. Signed copies are securely held by Clarity Informatics and are available on request with the permission of the individual. A copy of the declaration of interest form which participants are asked to complete annually is also available on request. A brief outline of the declarations of interest policy is described here and full details of the policy is available on the Clarity Informatics website. Declarations of interests of the authors are not routinely published, however competing interests of all those involved in the topic update or development are listed below. Competing interests include:

  • Personal financial interests
  • Personal family interest
  • Personal non-financial interest
  • Non-personal financial gain or benefit

Although particular attention is given to interests that could result in financial gains or losses for the individual, competing interests may also arise from academic competition or for political, personal, religious, and reputational reasons. An individual is not obliged to seek out knowledge of work done for, or on behalf of, the healthcare industry within the departments for which they are responsible if they would not normally expect to be informed.

Who should declare competing interests?

Any individual (or organization) involved in developing, reviewing, or commenting on clinical content, particularly the recommendations should declare competing interests. This includes the authoring team members, expert advisers, external reviewers of draft topics, individuals providing feedback on published topics, and Editorial Steering Group members. Declarations of interest are completed annually for authoring team and editorial steering group members, and are completed at the start of the topic update and development process for external stakeholders.

Competing interests declared for this topic:

None.

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