What does it do?

Promethazine is 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.

How should you take it?

Take promethazine as directed.
Take the tablets with a glass of water.
Measure the liquid 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)
  • antacids (e.g. Mylanta®)

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

Important information continues on next page.

What side effects might you notice?

Side EffectsRecommended action

Fast or irregular heartbeat, fainting

Tell your doctor immediately

Unusual behaviour or thinking, loss of co-ordination, confusion

Tell your doctor

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

Drowsiness, dizziness, headache


More sensitive to sunlight (sunburn or rash)

Stomach upset

Tell your doctor if troublesome

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

Other information:

  • Tell your doctor if you have liver, kidney, heart, lung, prostate, bowel or bladder problems.
  • Tell your doctor if you have angle-closure glaucoma or if you have ever had a seizure.
  • Tell your doctor if you are pregnant, planning to become pregnant, or breastfeeding.
  • Your doctor may do a heart test (ECG) before you start and while you are taking promethazine.
  • 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?)
  • Promethazine should not be used in children younger than 2 years of age unless prescribed by a specialist.
  • Do not take indigestion remedies, iron or calcium preparations within 2 hours of taking promethazine.
  • 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.