Safety information · Internal patient-safety page
Azithromycin safety summary
Azithromycin is a macrolide antibiotic used to treat chlamydia and other bacterial infections. It concentrates inside tissue and keeps working for several days after the last tablet, which is why a chlamydia course can be as short as a single dose.
What it's used for
- Take exactly as prescribed: for chlamydia this is often a single dose taken at once.
- Can be taken with or without food; food can ease a sensitive stomach.
- Avoid sex (including with condoms) for 7 days after a single-dose treatment, and until any partner has also been treated.
- Complete the full prescription even if symptoms settle early.
Most common side effects
- Diarrhoea or loose stools.
- Nausea, abdominal pain, wind.
- Headache.
- Dizziness.
- Changes in taste.
Serious side effects: stop and seek care
- Severe allergic reaction: rash, swelling of the face or throat, difficulty breathing.
- Severe skin reactions with blistering or peeling.
- Palpitations, a racing or irregular heartbeat, or fainting: azithromycin can prolong the heart's QT interval, especially alongside other medicines that do the same.
- Yellowing of the skin or eyes, dark urine (liver problems).
- Severe, watery or bloody diarrhoea, even weeks after finishing, can signal a C. difficile gut infection.
Who should not take it
- Allergy to azithromycin, erythromycin or any other macrolide antibiotic.
- A previous episode of jaundice or liver problems caused by a macrolide.
- Severe liver disease: discuss with the doctor first.
- Use extra caution with a known long-QT condition, a very slow heartbeat, or low blood potassium or magnesium.
Interactions to flag
- Other medicines that prolong the QT interval: some antiarrhythmics, antipsychotics and antidepressants.
- Antacids containing aluminium or magnesium: take azithromycin at least 1 hour before or 2 hours after.
- Ergot derivatives (for migraine): do not combine.
- Ciclosporin, digoxin and colchicine: levels can rise; monitoring may be needed.
- Warfarin and similar anticoagulants: bleeding tendency can increase.
Message us in the app chat if you notice any of these
- Rash, facial swelling or trouble breathing: call emergency services first.
- Palpitations, an irregular heartbeat or a fainting episode.
- Severe or bloody diarrhoea, during treatment or in the weeks after.
- Symptoms that have not improved a week after treatment.
AEMPS CIMA: Azithromycin 500 mg
Back to your consultationThis page summarises information from the regulator-approved leaflet for reference only. It is not medical advice and does not replace the assessment of an EU-licensed doctor. Your doctor will review your individual history, dose and interactions during your consultation.