Previous changes

May 2024 — minor update. Information added stating that concomitant treatment with clarithromycin and ivabradine is now contraindicated and caution is now advised when co-administering clarithromycin with edoxaban, as per the manufacturer's updated SPC.

December 2023 — minor update. Update to drug interactions section for erythromycin to include information on interactions with Lomitapide and Corticosteroids, as per the manufacturer's Summary of Product Characteristics (SPC).

November 2023 — minor update. Interactions section for flucloxacillin updated in line with updated manufacturer's summary of product characteristics.

July 2023 — minor update. The summary of manufacturer’s product characteristics for clarithromycin was updated to include a warning regarding concomitant treatment with domperidone (due to the risk of QT prolongation and cardiac arrhythmias).

August 2022 — reviewed. A literature search was conducted in August 2022 to identify evidence-based guidelines, UK policy, systematic reviews, and key randomized controlled trials published since the last revision of this topic. Supporting references have been added to the existing guidance, with no major changes made to the recommendations. Prescribing information has been added for topical fusidic acid cream. 

January 2021 — minor update. Contraindications and drug interactions for erythromycin have been updated in line with an MHRA drug safety update. 

January 2017 to May 2017 — reviewed. Literature searches were conducted in January 2017 to identify evidence-based guidelines, UK policy, systematic reviews, and key randomized controlled trials published since the last revision of the topic. There have been minor structural changes to the topic. Minor changes have been made including consideration of topical antibiotics and the removal of procedural directions for incision and drainage.

July 2015 — minor update. The prescribing information sections on erythromycin and clarithromycin have been clarified.

February 2013 — minor update. The 2013 QIPP options for local implementation have been added to this topic.

October 2012 — minor update. The 2012 QIPP options for local implementation have been added to this topic.

July 2011 — minor update. More exact paracetamol dosing for children has been introduced by the Medicines and Healthcare products Regulatory Agency. Prescriptions have been updated to reflect the revised dosing.

June 2011 — minor update. The 2010/2011 QIPP options for local implementation have been added to this topic. 

November 2010 to March 2011 — CKS topic revised. The evidence-base has been reviewed in detail, and recommendations are more clearly justified and transparently linked to the supporting evidence.

August 2007 — Oilatum Plus discontinued. Minor change to the text made and prescriptions removed. 

December 2006 to March 2007 — converted from CKS guidance to CKS topic structure. The evidence-base has been reviewed in detail, and recommendations are more clearly justified and transparently linked to the supporting evidence.

October 2006 — minor update. Analgesia prescriptions updated because new doses of ibuprofen for children are recommended by the British National Formulary. 

November 2005 — minor technical update. 

September 2003 — written. Validated in December 2003 and issued in February 2004.

New evidence

Evidence-based guidelines

No new evidence-based guidelines since 1 August 2022.

HTAs (Health Technology Assessments)

No new HTAs since 1 August 2022.

Economic appraisals

No new economic appraisals relevant to England since 1 August 2022.

Systematic reviews and meta-analyses

No new systematic review or meta-analysis since 1 August 2022.

Primary evidence

No new primary evidence which reaches the CKS threshold for inclusion published since 1 August 2022.

New policies

No new national policies or guidelines since 1 August 2022.

New safety alerts

No new safety alerts since 1 August 2022.

Changes in product availability

No changes in product availability since 1 August 2022.

Basis for recommendation

Typical symptoms of acute paronychia

• This information is based on expert opinion in review articles [Hsu, 2012; Leggit, 2017; Rerucha, 2019; BMJ Best Practice, 2020; Relhan and Bansal, 2022].

Findings on examination

• This information is based on expert opinion in review articles  [Piracinni, 2014; Leggit, 2017; Rerucha, 2019; BMJ Best Practice, 2020; Relhan and Bansal, 2022].

Digital pressure test

• The guidance on how to carry out a digital pressure test to assess for early infection is based on expert opinion in a review article [Leggit, 2017].

Symptoms indicating viral infection

• The guidance on symptoms which may be indicative of herpes simplex infection as the cause of acute paronychia s based on expert opinion in a review article [BMJ Best Practice, 2020].

Basis for recommendation

This information is based on expert opinion in review articles [Leggit, 2017; BMJ Best Practice, 2020; PCDS, 2022; Lee, 2022; Relhan and Bansal, 2022] and a case report of nail apparatus squamous cell carcinoma mimicking paronychia [Monica, 2019].

How should I manage a person with an acute paronychia?

• Advise the person to apply moist heat (warm soaks) for ten to fifteen minutes, three to four times a day to alleviate pain, localize the infection, and hasten draining of the pus ('bring to a head').
• Incision and drainage are recommended if a fluctuant pus collection or abscess has developed.
  • Incision and drainage may be performed in primary care if the expertise and facilities are available. Otherwise, the person should be referred to a surgical unit or Emergency department, according to local protocol.
• Consider prescribing topical antibiotics, such as fusidic acid cream, for minor, localised infection.
  • For further information, see Prescribing information.
• Consider prescribing a course of oral antibiotics if incision and drainage:
  • Is not performed.
  • Was performed, but the person has significant pain, involvement of an extended area of periungual tissue, signs of cellulitis or fever, or has other comorbidities (such as diabetes or immunosuppression).
    • Flucloxacillin or clarithromycin are recommended first line (erythromycin is generally preferred over clarithromycin in pregnant and breastfeeding women).
    • For further information, see Prescribing information.
• Seek specialist advice if the person is already known to have meticillin-resistant Staphylococcus aureus (MRSA) infection or a swab sample from the paronychia grows MRSA.
  • See the CKS topic on MRSA in primary care.
• Give the person self-care advice:
  • Advise all people to:
    • Take paracetamol or a nonsteroidal anti-inflammatory drug (NSAID) as required for pain relief.
    • Keep the affected areas clean and dry.
    • Avoid further trauma or manipulation of the nail.
    • Trim hang nails to a semi-lunar smooth edge and avoid biting nails or lateral nail folds.
  • If the person works with their hands in a moist environment (such as dish washers), advise that:
    • Frequent exposure to water (particularly with detergent) increases their risk of getting a paronychia.
    • Treatment is unlikely to be successful if exposure to the wet or moist environment continues.
    • They should wear gloves (preferably cotton lined) to protect fingers.
  • If the person is immunocompromised, advise that they should remain vigilant against any minor trauma to the finger tips and nails.
• Follow up is not usually necessary, as most paronychia drain spontaneously without the need for incision and drainage (if this has not already been performed). However, advise the person that they should:
  • Return for review if the paronychia becomes fluctuant (as it may require incision and drainage), or if it persists and does not discharge or improve.
  • Seek urgent medical advice if they become systemically unwell (for example if they develop a fever) or develop signs of a complication such as cellulitis.
• If the paronychia is due to an ingrowing toenail, this must be addressed.
  • The management of ingrowing toenail is not covered by this topic.

When should I take a swab in a person with acute paronychia?

• Consider taking a swab of the contents of a paronychia if:
  • The paronychia is enlarging.
  • There is inflammation of surrounding tissue.
  • The paronychia is recurrent.
  • The paronychia has not responded to treatment within 2 to 3 days.
  • The person is systemically unwell.
  • The person has a history of contact with methicillin-resistant Staphylococcus aureus (MRSA).
  • There is doubt about the diagnosis.
  • The person is immunosuppressed.
  • The person has diabetes.

How should I manage recurrent acute paronychia?

• Consider an alternative diagnosis, particularly herpetic whitlow, which can mimic recurrent paronychia.
  • See the CKS topic on Whitlow (staphylococcal and herpetic) for further information.
• Exclude other underlying causes, particularly recurrent trauma to the nails (such as nail biting) or frequent immersion of the hands in water.
• Swab the lesion (to confirm the causative organism and antibiotic sensitivities) and treat the person with the appropriate antibiotics.
  • If response is slow after 7 days of antibiotics, continue for a further 7 days.
  • If staphylococcal infection is confirmed, check the person for carriage of Staphylococcus aureus. See Scenario: Staphylococcal carriage in the CKS topic Boils, carbuncles, and staphylococcal carriage.
• If the person is already known to have methicillin-resistant Staphylococcus aureus (MRSA) infection or a swab sample of pus grows MRSA, see the CKS topic on MRSA in primary care for further information.
• Consider X-ray imaging in refractory acute paronychia to assess for osteomyelitis.
• Give self-care advice, including advice on preventing recurrence by:
  • Avoiding using cuticle removers or trimming the cuticle.
  • Avoiding trauma to the nails, such as picking, sucking, or biting.
  • Keeping the nails clean and dry.
• Advise people who work with their hands in moist environment (such as dish washers) that:
  • Frequent exposure to water (particularly with detergent) increases their risk of getting a paronychia.
  • They should wear gloves (preferably cotton lined) to protect fingers.
  • They should thoroughly dry hands with a clean towel and apply antibacterial moisturiser after washing.

Dose

• Adults and children: apply 3 to 4 times daily for 7 days.
  • To avoid the development of bacterial resistance, it is generally recommended that topical fusidic acid should not be used for longer than 10 days.

[ABPI, 2019; BNF, 2024]

Contraindications and cautions

• Do not prescribe topical fusidic acid to people with:
  • A history of hypersensitivity to either fusidic acid or any of the product excipients.
• Cautions:
  • Due to possible fire accelerant effects and the risk of severe burns, avoid contact with naked flames or burning material (including tobacco) after application.

[ABPI, 2019]

Adverse effects

• Adverse effects include:
  • Skin reactions such as pruritus, rash, erythema, angioedema, urticaria, blister.
  • Application site pain and irritation.

[ABPI, 2019; BNF, 2024]

Drug interactions

• There are no relevant drug interactions. 

[ABPI, 2019]

Dose

• Adults: 250–500 mg four times daily for 5–7 days.
• Children aged:
  • 1 month to 1 year: 62.5–125 mg four times daily for 5–7 days.
  • 2–9 years: 125–250 mg four times daily for 5–7 days.
  • 10–17 years: 250–500 mg four times daily for 5–7 days.

[BNF, 2024]

Contraindications and cautions

• Do not prescribe flucloxacillin in people with:
  • A true penicillin allergy — allergic reactions to penicillins occur in 1–10% of exposed individuals; anaphylactic reactions occur in fewer than 0.05% of treated people.
    • People with a history of atopy (e.g. asthma, eczema, hay fever) are at a higher risk of anaphylactic reactions to penicillins — people with a history of anaphylaxis, urticaria, or rash immediately after penicillin administration are at risk of immediate hypersensitivity and should not receive a penicillin.
    • People with a history of a minor rash (non-confluent, non-pruritic rash restricted to a small area of the body) or a rash that occurs more than 72 hours after penicillin administration are probably not allergic to penicillin and it should not be withheld unnecessarily for serious infections — the possibility of an allergic reaction should, however, be borne in mind.
  • History of flucloxacillin-associated jaundice or hepatic dysfunction.
• Prescribe flucloxacillin with caution in people with:
  • Hepatic dysfunction (not flucloxacillin-related), aged over 50 years, or with a serious underlying medical condition — these people are at increased risk of hepatic reactions.
  • Severe renal impairment — reduce the dose if the person's estimated glomerular filtration rate (eGFR) is less than 10 mL/minute/1.73 m².
  • A history of allergy — these people are more likely to develop a sensitivity reaction.

[EMC, 2023a; BNF, 2024]

Adverse effects

• Gastrointestinal — diarrhoea, nausea and vomiting (common).
  • Very rarely: antibiotic-associated colitis.
• Nervous system — headache, dizziness (uncommon).
• Skin and subcutaneous tissue — skin rash, urticaria and purpura (uncommon).
  • Very rarely: erythema multiforme, Stevens-Johnson syndrome, toxic epidermal necrolysis, acute generalised exanthematous pustulosis.
• Other rare, or very rare adverse effects include:
  • Anaphylaxis.
  • Arthralgia and myalgia (very rare) — may sometimes develop more than 48 hours after the start of the treatment.
  • Hepatitis, cholestatic jaundice — this may occur up to several weeks after treatment with flucloxacillin has been stopped. Risk factors include treatment for more than 2 weeks, and increasing age.
  • Interstitial nephritis.
  • Neutropenia, thrombocytopenia, haemolytic anaemia.

[EMC, 2023a; BNF, 2024]

Drug interactions

• Methotrexate — methotrexate clearance may be reduced, causing an increased risk of toxicity, however, serious interactions are uncommon. 
  • Standard routine monitoring will identify any decreases in elimination in people on high-dose regimens. For people on low-dose regimens, consult local or national guidelines/protocols for monitoring and management.
• Coumarin and indanedione anticoagulants (warfarin, phenidione) — consider increased monitoring of international normalized ratio (INR) and adjust the dose accordingly.
• Posaconazole, voriconazole — concentrations of antifungal is greatly decreased. If concurrent use is unavoidable, monitor for decreased efficacy and consider increasing the dose of the azole (although this may not resolve the issue). 
• Probenecid — concomitant administration may result in increased levels of flucloxacillin.
• Live cholera vaccine — efficacy of vaccine may be reduced. Avoid flucloxacillin from 14 days before to 10 days after receiving live cholera vaccine.
• Live typhoid vaccine — immune response to vaccine may be reduced. Avoid flucloxacillin from 3 days before to 3 days after receiving live typhoid vaccine.

[Preston, 2023]

Dose

• Adults: 250–500 mg twice daily for 5–7 days.
• Children aged:
  • 1 month to 11 years with body weight:
    • Less than 8 kg: 7.5 mg per kg twice daily for 5–7 days.
    • 8–11 kg: 62.5 mg twice daily for 5–7 days.
    • 12–19 kg: 125 mg twice daily for 5–7 days.
    • 20–29 kg: 187.5 mg twice daily for 5–7 days.
    • 30–40 kg: 250 mg twice daily for 5–7 days.
  • 12 years and over:  250–500 mg twice daily for 5–7 days.

[BNF, 2024]

Contraindications and cautions

• Do not prescribe clarithromycin to people with:
  
  • A history of QT prolongation or ventricular cardiac arrhythmia, including Torsades de pointes.
  • Conditions that predispose to QT interval prolongation, such as electrolyte disturbances (hypokalaemia or hypomagnesaemia) or the use of some medications that prolong the QT interval.
  • Severe hepatic impairment in combination with renal impairment.
• Prescribe clarithromycin with caution to people with:
  • Hepatic impairment (or concurrently receiving potentially hepatotoxic drugs).
  • Moderate to severe renal impairment.
    • For immediate-release preparations: if creatinine clearance (CrCl) is less than 30 mL/minute, prescribe half the normal dose and use for a maximum duration of 14 days.
    • For modified-release preparations: if CrCl is 30–60 mL/minute, prescribe half the normal dose. Avoid if CrCl is less than 30 mL/minute.
  • Myasthenia gravis — macrolides may aggravate weakness symptoms.
  • Other risk factors for QT prolongation, such as:
    • Coronary artery disease, severe cardiac insufficiency, conduction disturbances, or clinically relevant bradycardia.
    • The use of some medications associated with QT prolongation. 

[EMC, 2023b; BNF, 2024]

Adverse effects

• Cardiac — cardiac arrest, atrial fibrillation, QT interval prolongation (uncommon).
  • Rarely: Torsades de pointes, ventricular tachycardia, ventricular fibrillation.
• Gastrointestinal — diarrhoea, vomiting, dyspepsia, nausea, abdominal pain (common).
  • Rarely: pancreatitis, pseudomembranous colitis. For more information, see the CKS topic on Diarrhoea - antibiotic associated.
• Nervous system — headache, dysgeusia (common), dizziness, somnolence, tremor (uncommon).
  • Rarely: convulsions, paraesthesia.
• Psychiatric — insomnia (common), anxiety, nervousness (uncommon).
  • Rarely or very rarely: psychotic disorders, depression, mania, hallucination.
• Skin — rash, hyperhidrosis (common), pruritus, urticaria (uncommon).
  • Rarely, or very rarely: Drug Reaction with Eosinophilia and Systemic Symptoms (DRESS), Stevens-Johnson syndrome, toxic epidermal necrolysis, acute generalised exanthematous pustulosis (AGEP).
• Other adverse effects reported rarely, or very rarely, include: 
  • Anaphylaxis.
  • Deafness.
  • Hepatic failure, jaundice.
  • Pancreatitis. 
  • Renal failure, interstitial nephritis.
  • Rhabdomyolysis, myopathy.

[EMC, 2023b; BNF, 2024]

Drug interactions

• CYP3A enzyme inducers (rifampicin, carbamazepine, phenobarbital) — these may induce the metabolism of clarithromycin, resulting in sub-therapeutic levels.
  • It may be necessary to monitor the levels of these drugs, as CYP3A is inhibited by clarithromycin leading to higher plasma levels of the inducer.
• Concurrent use with clarithromycin increases exposure to the following drugs: 
  • Calcium channel blockers (verapamil, amlodipine, diltiazem) —  monitor for adverse effects (for example, bradycardia, hypotension, headache, oedema) and reduce the calcium-channel blocker dose as necessary.
  • Ciclosporin — if concurrent use is necessary, monitor ciclosporin levels and adjust the dose accordingly.
  • Colchicine — concurrent use is contraindicated. 
  • Digoxin — monitor for signs of adverse effects, measure digoxin levels and reduce the digoxin dose if required.
  • Ivabradine — concomitant treatment is contra-indicated, owing to CYP3A4 inhibition by clarithromycin which can cause elevated levels of ivabradine.
  • Midazolam — reduce oral dose by 50 to 75%, and advise patients about sedative risk.
  • Oral anticoagulants (such as direct-acting oral anticoagulants [DOACs] and warfarin) — there is a risk of serious haemorrhage and significant elevations in international normalized ratio (INR) and prothrombin time when co-administered with clarithromycin.
    • DOACs — monitor for signs and symptoms of bleeding or anaemia, especially, in elderly people and those with renal impairment. 
    • Warfarin — monitor INR and prothrombin times closely during concurrent treatment with clarithromycin
  • Statins —  increased risk of myopathy.
    • Lovastatin, simvastatin — concurrent use is contraindicated. If treatment with clarithromycin cannot be avoided, stop treatment with statin temporarily.
    • Atorvastatin — levels moderately increased with concurrent use. Temporarily withhold statin, or if necessary, reduce dose and warn patients to report any unexplained muscle pain or weakness. 
  • Tacrolimus — large increases in tacrolimus concentrations and renal toxicity have been reported with clarithromycin. Both clarithromycin and tacrolimus have been associated with QT prolongation or torsade de pointes but an effect is not established. Monitor the concentrations and effects (e.g. on renal function) of tacrolimus more frequently if clarithromycin is started or stopped, adjusting the tacrolimus dose as necessary.
  • Ticagrelor — avoid concurrent use.
  • Ranolazine — may increase risk of QT interval prolongation. Avoid concurrent use.  
  • Rimegepant — avoid concurrent use. 
  • Daridorexant — avoid concurrent use.
  • Eletriptan — concurrent use is contraindicated.
  • Edoxaban — manufacturer advises caution with concurrent treatment with edoxaban, particularly in those with a high risk of bleeding.
  • Eplerenone, finerenone — concurrent use is contraindicated.
  • Quetiapine — concurrent use is contraindicated.
• Ergot alkaloids — concurrent administration is contraindicated, due to the risk of acute ergot toxicity.
• Oral hypoglycaemic drugs (sulfonylureas) and insulin — the concurrent use of clarithromycin and oral hypoglycaemic drugs and/or insulin can result in significant hypoglycaemia. Monitor glucose levels.
• Drugs that cause hypokalaemia — hypokalaemia is a risk factor for QT prolongation.
  • Avoid concurrent treatment with drugs that increase the risk of hypokalaemia, such as diuretics, corticosteroids, and short-acting beta-2 agonists.
• Drugs that prolong the QT interval — all macrolides can prolong the QT interval, and caution is advised with concurrent use. Concurrent use is contraindicated with domperidone,dronedarone, ivabradine, mizolastine, astemizole, cisapride, pimozide and terfenadine.
  • Hydroxychloroquine — The Medicines and Healthcare products Regulatory Agency (MHRA) advises caution.
• Live cholera vaccines — the efficacy of the live vaccine may be affected. Avoid concurrent use and for 14 days before, and for 10 days after, live cholera vaccines.
• Live typhoid vaccines — the immune response to the vaccine may be reduced. Antibacterials should be stopped from 3 days before to 3 days after receiving live typhoid vaccines.

[MHRA, 2020; Preston, 2023]

Dose

• Adults: 250–500 mg four times daily for 5–7 days.
• Children aged:
  • 1–23 months: 125 mg four times daily for 5–7 days.
  • 2–7 years: 250 mg four times daily for 5–7 days.
  • 8–17 years: 250–500 mg four times daily for 5–7 days.

[BNF, 2024]

Contraindications and cautions

• Do not prescribe erythromycin to people with: 
  • Acute porphyrias.
  • A history of QT interval prolongation (congenital or acquired) or ventricular cardiac arrhythmia, including torsades de pointes.
  • Electrolyte disturbances (such as hypokalaemia or hypomagnesaemia) — due to the risk of arrhythmia associated with QT interval prolongation.
• Prescribe erythromycin with caution to people with:
  
  • Predisposition to QT interval prolongation.
  • Coronary artery disease, severe cardiac insufficiency, conduction disturbances or clinically relevant bradycardia.
  • Hepatic impairment.
  • Myasthenia gravis.

[MHRA, 2020; EMC, 2023c; BNF, 2024]

Adverse effects

• Gastrointestinal (GI) — diarrhoea, GI discomfort/disorders, nausea, vomiting, pancreatitis (common or very common); constipation (uncommon).
  • Rare or very rare: antibiotic-associated colitis.
• Cardiovascular — QTc interval prolongation, torsades de pointes, palpitations and cardiac rhythm disorders, including ventricular tachyarrhythmias (uncommon).
• Ear and labyrinth disorders — hearing impairment, tinnitus.
• Hepatobiliary — cholestatic hepatitis, jaundice, hepatic disfunction, hepatomegaly, hepatic failure, hepatocellular hepatitis.
• Skin and subcutaneous tissues — skin reactions (common or very common); Stevens-Johnson syndrome, toxic epidermal necrolysis, erythema multiforme (uncommon); acute generalised exanthematous pustulosis (AGEP) (frequency unknown).
• Other common adverse effects include:
  • Dizziness.
  • Headache.
  • Vasodilation.
  • Vision disorders.

[EMC, 2023c; BNF, 2024]

Drug interactions

• Aminophylline, theophylline — aminophylline can cause hypokalaemia (potentially increasing the risk of torsade de pointes) when given with erythromycin. Theophylline clearance (from aminophylline) can be reduced if given concurrently with erythromycin. Oral erythromycin exposure may be reduced by theophylline. Monitor theophylline levels after 48 hours and adjust the dose accordingly. Monitor potassium concentrations closely and the effects of oral erythromycin to ensure they are adequate. Consider giving an alternative antibiotic. 
• Calcium channel blockers (amlodipine, diltiazem) — erythromycin possibly inhibits the metabolism of calcium channel blockers, increasing the risk of adverse effects, such as hypotension. Monitor for adverse effects (for example, bradycardia, hypotension, headache, oedema) and reduce the calcium channel blocker dose as necessary.
• Rifampicin — may induce the metabolism of clarithromycin, resulting in sub-therapeutic levels.
  • If concurrent use is necessary, monitor erythromycin efficacy closely.
• Carbamazepine — erythromycin can increase carbamazepine levels, causing carbamazepine toxicity (which may present as nausea and vomiting, ataxia, and drowsiness).
  • Avoid concurrent use, unless carbamazepine levels can be monitored closely. 
• Ciclosporin — levels are greatly increased by erythromycin. Monitor concentrations and effects (for example, renal function) more frequently if erythromycin is started or stopped. Adjust the ciclosporin dose as required. 
• Cisapride, domperidone — levels may be raised, increasing the risk of potentially life-threatening arrhythmias (torsade de pointes). Concurrent use is contraindicated.
• Colchicine — erythromycin possibly increases the risk of colchicine toxicity.
  • Stop or reduce the dose of colchicine.
  • Avoid concurrent use in renal or hepatic impairment.
• Corticosteroids — levels of corticosteroids may be increased. Monitor for corticosteroid adverse effects (such as moon face, weight gain, hyperglycaemia), and adjust the corticosteroid dose or stop the macrolide as appropriate. 
• Drugs that prolong the QT interval (such as amiodarone, amisulpride, fluconazole, sildenafil, mizolastine, hydroxyzine) — macrolides can also prolong the QT interval, increasing the risk of arrhythmias (such as torsades de pointes).
  • Concurrent use of drugs that prolong the QT interval is contraindicated.
• Drugs that cause hypokalaemia (such as diuretics, corticosteroids, short-acting beta-2 agonists) — hypokalaemia is a risk factor for QT prolongation. Monitor potassium levels closely. 
• Digoxin — erythromycin may increase the concentration of digoxin. 
  • Monitor digoxin concentration.
• Edoxaban — erythromycin slightly increases edoxaban levels. Decrease dose of edoxaban to 30 mg once daily. Monitor for signs and symptoms of bleeding. 
• Ergot alkaloids (such as ergotamine and dihydroergotamine) — concurrent use with erythromycin may result in acute ergot toxicity. 
  • Concurrent use is contraindicated.
• Lomitapide — concurrent use with erythromycin increases transaminase levels and is contraindicated.
• Protease inhibitors (ritonavir, saquinavir) — erythromycin levels may be increased. Monitor for adverse effects. 
• Statins — there is an increased risk of myopathy (due to cytochrome P450 enzyme CYP3A4 inhibition) [MHRA, 2014].    
  • Lovastatin, simvastatin  — concurrent use is contraindicated. If erythromycin treatment cannot be avoided, withhold the statin during the course of the treatment.
  • Atorvastatin — levels of atorvastatin increased slightly with concurrent use. Temporarily withhold the statin, or if necessary give the lowest dose of statin and advise the person to seek medical advice if they experience symptoms of myopathy (for example muscle pain, tenderness, or weakness).
  • Pravastatin — prescribe erythromycin with caution, and advise the person to report any muscle pain, tenderness, or weakness.
• Quetiapine — erythromycin increases the plasma concentration of quetiapine and both drugs are associated with QT interval prolongation.
  • Concurrent use is contraindicated, but if necessary, monitor for quetiapine adverse effects (for example, somnolence, dry mouth, tachycardia) and reduce the dose if needed.
• Coumarin anticoagulants (such as warfarin) — erythromycin may cause a minor increase in warfarin effects. Consider increased monitoring of the international normalized ratio (INR) when both drugs are used (particularly in elderly people), and adjust the warfarin dose accordingly. 
• Live cholera vaccines — the efficacy of the live vaccine may be affected. Avoid concurrent use and for 14 days before, and for 10 days after, live cholera vaccines.
• Live typhoid vaccines — the immune response to the vaccine may be reduced. Antibacterials should be stopped from 3 days before to 3 days after receiving live typhoid vaccines.

[MHRA, 2020; Preston, 2023]