NZ Formulary

Benzathine penicillin

ben-zah-theen pen-ih-sil-in

What does it do?

Benzathine penicillin is an antibiotic used to treat and prevent bacterial infections.

Before you start

  • Tell your doctor if you have kidney problems, or if you are allergic to penicillin antibiotics.
  • Tell your doctor if you are pregnant, planning to become pregnant, or breastfeeding.

How is it given?

Benzathine penicillin is given as an injection into a muscle. It is usually given to you by a health professional. 

What if you forget a dose?

Contact your health professional as soon as possible. Usually, the missed dose is given as soon as possible, and treatment continued as directed. 

Can you take other medicines?

Tell your pharmacist or doctor about all medicines or treatments that you may be taking, including vitamins, herbal products or recreational drugs.

What side effects might you notice?

Side EffectsRecommended action

Symptoms of allergy including: skin rash, itching, swelling, trouble breathing

Tell your health professional immediately

Severe or persistent diarrhoea, abdominal pain

Tell your health professional

Irritation or pain at injection site

Tell your health professional if troublesome

If you notice any other effects, discuss them with your doctor or pharmacist.

Other information:

  • If you are getting benzathine penicillin for syphilis, you may get flu-like symptoms (fever, chills, aches and pains) after the first injection as your body reacts to the bacteria dying. This usually passes after a few hours. Rest, drink plenty of fluids and take paracetamol if needed. If it continues to bother you, contact your health professional.