NZ Formulary

Promethazine

pro-meth-ah-zeen

What does it do?

Promethazine is an antihistamine used to treat and prevent allergic conditions such as hayfever and skin rashes. It is also used for nausea and vomiting, or to help you sleep.

Before you start

  • Tell your doctor if you have bladder, prostate or bowel problems, or angle-closure glaucoma.
  • Tell your doctor if you are pregnant, planning to become pregnant, or breastfeeding.

How should you take it?

Take promethazine as directed. You can take it with or without food.
Tablet: Take with a glass of water.
Liquid: Measure carefully with an oral syringe or measuring spoon.

What if you forget a dose?

If you take promethazine regularly and it is nearly time for your next dose, skip the missed dose and take your next dose at the usual time. Otherwise, take the missed dose as soon as you remember. Do not take two doses at the same time.

Can you take other medicines?

Some medicines available without a prescription may react with promethazine including:

  • other antihistamines (may be in anti-allergy, anti-nausea and cough/cold medicines)
  • other medicines that may cause drowsiness (e.g. pain-killers, anti-nausea and cough/cold medicines – ask your pharmacist)

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

Confusion

Tell your doctor

Dry mouth, blurred vision, constipation or trouble peeing (anticholinergic effects)

Drowsiness

More sensitive to sunlight (sunburn or rash)

Tell your doctor if troublesome

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

Other information:

  • Promethazine can impair your ability to do tasks such as driving or using machines. Alcohol makes this worse. Discuss your risk with your health professional. (search NZTA - Are you safe to drive?)
  • Protect yourself from too much sunlight while being treated with promethazine. Always cover up and apply a thick layer of broad spectrum sunscreen (at least SPF 30) when outside. Do not use sunbeds.