Pharmacy First: Impetigo

About this service

Impetigo is a superficial bacterial skin infection caused by Staphylococcus aureus and sometimes Streptococcus pyogenes.¹ It is highly contagious and most common in children, though it can affect any age group. The NHS Pharmacy First pathway covers non-bullous impetigo in children aged 1 year and over and adults who are systemically well.

The pathway has a clear treatment structure based on how many lesions are present. Localised impetigo (3 or fewer lesions or clusters) is treated topically: hydrogen peroxide 1% cream (Pharmacy First protocol 3a) is first line, and fusidic acid 2% cream (PGD 3b) is second line only when hydrogen peroxide is unsuitable or has not worked.^1,2,3 Widespread impetigo (4 or more lesions or clusters) requires oral treatment: flucloxacillin (PGD 3c) is first line; clarithromycin (PGD 3d) if there is confirmed penicillin or beta-lactam hypersensitivity; erythromycin (PGD 3e) for pregnant individuals aged 16 and over where flucloxacillin is not appropriate due to penicillin hypersensitivity.^4,5,6

Bullous impetigo is entirely outside this pathway. It requires referral to a GP and must not be treated under any Pharmacy First impetigo PGD or protocol. The ability to distinguish non-bullous from bullous impetigo is therefore a core clinical requirement for delivering this service.

Who to offer the service to

Include

• Aged 1 year and over
• Non-bullous impetigo confirmed (see clinical features below)
• Systemically well (not unwell, no fever, no systemic signs)
• NHS eligibility requirements apply

Exclude

• Under 1 year old: outside the Pharmacy First pathway. Refer to GP.
• Pregnancy under 16: excluded. Pregnant individuals aged 16 and over with widespread impetigo and penicillin hypersensitivity may be treated under erythromycin PGD 3e. Erythromycin is not the default for all pregnant patients.
• Currently breastfeeding with impetigo lesions on the breasts: excluded. If lesions are elsewhere, topical and oral treatments may be used with monitoring and with advice to avoid direct contact between the infant and the lesions.
• Bullous impetigo: refer to GP urgently. Do not treat under any Pharmacy First impetigo PGD or protocol.
• Severely immunocompromised: refer to A&E urgently.
• Immunosuppressed (any degree, including patients on immunosuppressant medicines or long-term steroids) with localised impetigo: refer to GP or prescriber same day. Do not supply topical treatment under this pathway.
• Immunosuppressed with widespread impetigo: refer to A&E urgently.
• Recurrent impetigo (2 or more episodes in the same year): refer to GP.
• Active underlying skin condition that is currently uncontrolled: active eczema, contact dermatitis, scabies, chickenpox, or eczema herpeticum. Refer to GP.
• Failed previous oral antimicrobial treatment for this episode, or failed any antimicrobial other than hydrogen peroxide: refer to GP. Note: a patient who has tried hydrogen peroxide and not improved may still receive fusidic acid (PGD 3b second line), provided impetigo remains localised and all other eligibility criteria are met.
• Known MRSA colonisation or infection (applies to oral PGDs 3c, 3d, 3e): refer to GP.
• Known liver disease or previous flucloxacillin-associated jaundice (applies to oral flucloxacillin): refer to GP.
• Signs of a more serious illness: large blisters, pus, severe swelling, severe pain, spreading redness, or suspected cellulitis or Staphylococcal scalded skin syndrome: refer to A&E urgently.
• Systemically unwell: refer to GP or A&E depending on severity.
• Sepsis suspected: call 999.

How to deliver the service

1. Confirm the diagnosis and exclude bullous impetigo Impetigo presents as small vesicles or pustules that rupture quickly and leave golden or honey-coloured crusts, typically around the nose and mouth or on the limbs. Bullous impetigo is characterised by larger fluid-filled blisters (1-2cm) that persist for 2-3 days before rupturing to leave a thin flat yellow-brown crust. If the lesions look more like blisters than crusts, or if the crust is thin and flat rather than thick and honey-coloured, consider bullous impetigo and refer to GP rather than treating. Do not supply any Pharmacy First treatment for bullous impetigo.
2. Count the lesions and determine topical or oral treatment 3 or fewer lesions or clusters: localised impetigo, treat topically. 4 or more lesions or clusters: widespread impetigo, treat orally. Check for active underlying skin conditions (active eczema, scabies, chickenpox, eczema herpeticum) which exclude the patient from this pathway. Confirm the patient is systemically well.
3. For localised impetigo: select the correct topical treatment Hydrogen peroxide 1% cream (Crystacide, protocol 3a) is first line. Apply up to three times daily for 5 days. Note: use in children aged 1 year to under 2 years and in those aged 12 to 17 years is off-label, but it is supported by NICE NG153 and included in the NHS England protocol. Document this as part of informed consent where applicable. Fusidic acid 2% cream (PGD 3b) is second line only: use it if hydrogen peroxide is unsuitable (for example impetigo around the eyes) or has been tried and has not worked and impetigo remains localised. Do not supply fusidic acid if the patient smokes or cannot stay away from open or naked flames: this is a PGD exclusion because of severe burns risk. Fabric that contacts fusidic acid cream remains a fire hazard even after washing; counsel the patient on this. Before supplying fusidic acid, ask specifically whether the patient has ever used fusidic acid cream before for any condition: any previous use for any indication is an exclusion due to resistance risk.
4. For widespread impetigo: select and check the correct oral treatment Flucloxacillin (PGD 3c) is first line. Before supplying, check the following. Contraindicated medicines: methotrexate, probenecid, and voriconazole must not be used concurrently. Paracetamol and HAGMA risk: do not supply flucloxacillin if the patient has recent or current paracetamol use and risk factors for high anion gap metabolic acidosis, such as malnutrition, sepsis, or renal impairment. Refer to a prescriber. Other checks: warfarin (INR monitoring advised), known liver disease or previous flucloxacillin-associated jaundice (both excluded), CKD stage 5 (refer to GP), and oral typhoid vaccine timing (flucloxacillin may reduce its effectiveness). Counsel on empty stomach dosing: 1 hour before food or 2 hours after food. For children who find the taste difficult, the dose may be mixed with a small amount of water or fruit juice and given immediately.
   
   If confirmed penicillin or beta-lactam hypersensitivity: use clarithromycin (PGD 3d). Children aged 1-11 years: dose by weight using BNF for Children. Aged 12-17 years and adults: 250mg twice daily for 5 days. Before supplying, screen for the following four categories of risk. QT-prolonging medicines: do not supply if the patient takes terfenadine, astemizole, pimozide, cisapride, ergot derivatives, mizolastine, quinine, hydroxychloroquine, or any other medicine that prolongs the QT interval; also exclude if there is known QT prolongation, ventricular arrhythmia, or known electrolyte disturbance (hypokalaemia or hypomagnesaemia). CYP3A4 contraindications: lercanidipine is contraindicated; simvastatin and lovastatin must not be used concurrently; colchicine and lomitapide require individual assessment. Interacting medicines requiring referral or monitoring: warfarin and anticoagulants (increased bleeding risk, monitoring needed); ivabradine and quetiapine (refer to prescriber); digoxin (increased plasma levels). Strong CYP3A4 inducers (such as rifampicin, carbamazepine, phenytoin): these may reduce clarithromycin efficacy; refer to prescriber. Additional exclusions: known myasthenia gravis (do not supply, refer to prescriber); CKD stage 4 or 5; severe liver disease; current long-term macrolide use; ketogenic diet; pregnancy or suspected pregnancy; oral typhoid vaccine timing issue.
   
   If pregnant (aged 16 and over) with confirmed penicillin hypersensitivity: use erythromycin (PGD 3e). Dose: 500mg four times daily for 5 days, taken with water just before or with food. Erythromycin is excluded if the patient has: known myasthenia gravis; QT prolongation or ventricular arrhythmia; QT-prolonging medicines; hypokalaemia or hypomagnesaemia; known heart disease; porphyria; CKD stage 5; known or suspected liver disease; potentially hepatotoxic medicines; current long-term macrolide use; ketogenic diet; oral typhoid vaccine timing issue; or medicines where concomitant erythromycin is contraindicated, including lercanidipine, ivabradine, quetiapine, and lomitapide. Do not supply erythromycin to non-pregnant patients or to pregnant patients who can tolerate flucloxacillin.
5. Give contagion advice and safety net Impetigo is highly contagious. The patient is no longer contagious 48 hours after starting treatment, or when lesions are healed, dry, and crusted if no treatment is given. Advise: stay away from school or work until no longer contagious, inform the school or nursery, wash hands before and after applying cream, wash flannels, sheets, and towels at a high temperature, and wipe toys with detergent and warm water. Food handlers are required by law to inform their employer immediately.⁷ If you suspect a significant local outbreak (for example in a school, nursery, care home, or similar setting), consider informing the local health protection team or consultant in communicable disease control. Safety netting: seek urgent help if lesions spread rapidly, new blisters appear or existing ones enlarge, or the patient becomes systemically unwell.

Treatment outcome by presentation

Clinical Features: Non-Bullous versus Bullous Impetigo

Distinguishing non-bullous from bullous impetigo is essential. Bullous impetigo is outside this pathway and requires GP referral.

Treatment Decision by Lesion Count

Count lesions or clusters at assessment. The lesion count determines whether topical or oral treatment is appropriate.

Flucloxacillin Doses for Widespread Impetigo (PGD 3c): four times daily, empty stomach, 5 days

Take 1 hour before food or 2 hours after food. Check for interactions before supplying: methotrexate, probenecid, and voriconazole are contraindicated. In patients at risk of high anion gap metabolic acidosis (malnutrition, severe renal impairment, or sepsis) with recent or current paracetamol use, flucloxacillin is excluded under PGD 3c: refer to a prescriber.

Recording and submission

• Complete the consultation record contemporaneously on PharmOutcomes.
• Key information to record:
  • Patient name, date of birth, NHS number (where available)
  • Lesion count and distribution: number of lesions or clusters and anatomical location
  • Lesion type confirmed: non-bullous (crusted) or bullous (blistered). If bullous: referral documented.
  • Systemically well confirmed
  • Immune status confirmed: not immunosuppressed or severely immunocompromised (or referral documented)
  • Active underlying skin condition excluded
  • Recurrent impetigo excluded (first episode this year or none in the past year)
  • Treatment pathway selected and rationale: localised topical (H2O2 or fusidic acid) or widespread oral (flucloxacillin, clarithromycin, or erythromycin)
  • For fusidic acid: previous use for any indication excluded, fire hazard assessed (smoking or open flames)
  • For flucloxacillin: penicillin allergy status confirmed, drug interactions checked (methotrexate, probenecid, voriconazole, warfarin), paracetamol/HAGMA risk checked where relevant, liver disease excluded, CKD stage 5 excluded, oral typhoid vaccine timing checked
  • For clarithromycin: penicillin or beta-lactam hypersensitivity basis documented, QT-prolonging medicines checked, CYP3A4 contraindications checked (lercanidipine, simvastatin, lovastatin), interacting medicines reviewed (warfarin, ivabradine, quetiapine, digoxin), myasthenia gravis excluded, hepatic or renal impairment considered
  • For erythromycin: pregnancy confirmed, penicillin hypersensitivity confirmed, gestational age documented where possible, contraindicated medicines checked (lercanidipine, ivabradine, quetiapine, lomitapide)
  • Medicine supplied: name, strength, dose, frequency, duration, quantity, batch number, expiry date, PGD number
  • Verbal consent to supply obtained and recorded
  • Contagion advice given: school or work exclusion, hygiene measures, food handler notification if applicable
  • Safety netting provided and documented
  • GP notification submitted via PharmOutcomes where required by local service specification

Key takeaways

• Count the lesions first: 3 or fewer means topical treatment (hydrogen peroxide first line, fusidic acid second line only); 4 or more means oral treatment (flucloxacillin first line, clarithromycin for penicillin allergy, erythromycin for pregnant penicillin-allergic patients aged 16 and over). Bullous impetigo requires GP referral regardless of lesion count.
• Fusidic acid is second line only, requires no previous use for any indication, and must not be supplied to patients who smoke or are near naked flames due to fire risk. For flucloxacillin, screen for the paracetamol and HAGMA risk exclusion alongside methotrexate, probenecid, and voriconazole. Erythromycin (PGD 3e) is not the default for all pregnant patients: it applies only where flucloxacillin is not appropriate due to penicillin hypersensitivity.
• Impetigo is highly contagious: patients must stay away from school or work until 48 hours after starting treatment, and food handlers must notify their employer by law.

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