Treat Sinusitis With Clarithromycin

Clarithromycin is a macrolide antibiotic used to treat impetigo when first-line antibiotics (flucloxacillin) are not suitable — for example, in patients with a penicillin allergy. Impetigo is a highly contagious bacterial skin infection most commonly caused by Staphylococcus aureus or Streptococcus pyogenes. Clarithromycin works by inhibiting bacterial protein synthesis, killing the bacteria responsible for the infection. It is available as 250 mg and 500 mg tablets and as an oral suspension for children. Through the NHS Pharmacy First service, a pharmacist can supply clarithromycin for impetigo without a GP appointment.

Adults and children over 12 years: 250 mg twice daily for 5–7 days. Children aged 1–11 years: the dose is based on body weight, typically given as an oral suspension twice daily for 5–7 days. Your pharmacist will calculate the correct dose for children. Take clarithromycin at regular 12-hour intervals (e.g., morning and evening) to maintain effective antibiotic levels. Complete the full course even if the impetigo appears to be healing.

Clarithromycin is typically used for impetigo when flucloxacillin (the first-line oral antibiotic) is not suitable. The most common reason is penicillin allergy, as flucloxacillin is a penicillin-type antibiotic. Clarithromycin may also be preferred if there are drug interactions with other medications the patient is taking. NICE Clinical Knowledge Summaries recommend clarithromycin as the first-choice alternative to flucloxacillin for impetigo in penicillin-allergic patients.

Yes, the NHS Pharmacy First service allows community pharmacists to assess and treat impetigo directly, including supplying clarithromycin where clinically appropriate, without needing a GP appointment. The pharmacist will examine the affected skin, confirm a clinical diagnosis of impetigo, and determine whether topical treatment (such as fusidic acid or hydrogen peroxide cream) or oral antibiotics are needed. If oral antibiotics are required and you are allergic to penicillin, the pharmacist can supply clarithromycin. This service is free on the NHS.

Common side effects include nausea, vomiting, diarrhoea, abdominal pain, and taste disturbance (a metallic or bitter taste is very common with clarithromycin). Headache and insomnia may also occur. These side effects are generally mild and resolve after completing the course. Rare but serious side effects include allergic reactions, liver problems (jaundice, dark urine), and QT prolongation (abnormal heart rhythm). If you develop severe diarrhoea, skin rash, or jaundice, stop clarithromycin and seek medical advice.

Keep the affected skin clean by gently washing with soap and water. Do not scratch or pick at the sores. Cover exposed sores with a loose dressing to reduce spread. Impetigo is highly contagious — wash hands frequently, avoid sharing towels, flannels, and bedding, and avoid close contact with others until 48 hours after starting antibiotics or until the sores have crusted over and healed. Children should stay away from school or nursery until 48 hours after starting treatment.