Benzylpenicillin
Also sold as: Crystapen
Prescription neededPenicillins
Comes as:Injection
Usual adult dose
Dose is set by your doctor. Given by injection into a vein or muscle in hospital, several times a day, for serious infections such as pneumonia or meningitis.
Your doctor may give you a different dose. Children's doses depend on weight.
Side effects
Common
- pain at the injection site
- diarrhoea
- mild skin rash
Serious — get help
Stop taking it and see a doctor straight away if you notice:
- severe allergic reaction (swelling of face or throat
- difficulty breathing)
- seizures with very high doses
Do not take it, or take care, if
- Allergy to penicillin or any penicillin-type antibiotic
- Severe kidney disease (dose must be lowered)
- Epilepsy (use with caution at high doses)
Interactions
Medicines that can react with this one.
Moderate1 medicineTake together only with care. Ask your doctor or pharmacist.
- Methotrexate
Penicillins can reduce methotrexate clearance and raise its toxicity.