Promethazine is an antihistamine medicine that relieves the symptoms of allergies.
It's known as a drowsy (sedating) antihistamine. This means that it's likely to make you feel more sleepy than some other antihistamines.
Promethazine is used for:
- allergies, including hay fever and hives (urticaria)
- feeling and being sick (vomiting) – due to motion sickness or vertigo
- short-term sleep problems – including when a cough, a cold or itching is keeping you awake at night
You can buy promethazine from pharmacies, where it's often sold as Phenergan or Sominex. Promethazine is also available on prescription.
It comes as tablets or a liquid that you swallow.
Promethazine is sometimes mixed with other medicines, such as paracetamol or dextromethorphan, to treat cough and cold symptoms or pain.
Brand names of promethazine mixed with other medicines include Fedril and Night Nurse.
Key facts
- Do not drink alcohol while taking promethazine. Alcohol increases the risks of side effects.
- To prevent motion sickness, take promethazine the night before a long journey. Some products can be taken 1 to 2 hours before travelling, if it's a short journey.
- To help you sleep, take promethazine 20 minutes before you go to bed. It normally takes about 30 minutes to work.
- Side effects of promethazine include drowsiness, headaches, nightmares and feeling dizzy, restless or confused.
- Do not drive a car or ride a bike if it makes you sleepy or dizzy.