Taking promethazine with other medicines and herbal supplements - Brand names: Phenergan, Sominex

Cautions with other medicines

Some medicines and promethazine can affect each other and increase the chance of having side effects.

Check with a pharmacist or your doctor if you're taking any other medicines, including:

• any antidepressants, including monoamine oxidase inhibitors such as phenelzine, or other medicines for mental health conditions
• medicines used to treat an irregular heartbeat (arrhythmia), such as amiodarone
• medicines to treat epilepsy or seizures
• antibiotics to treat an infection, such as erythromycin
• a type of painkiller called an opioid, such as codeine, morphine or oxycodone
• any medicine that makes you drowsy, gives you a dry mouth, or makes it difficult for you to pee – taking promethazine might make these side effects worse

If you're taking a cough or cold remedy or a painkiller containing promethazine, check carefully what the other ingredients are.

For example, promethazine often comes mixed with paracetamol. If you take 2 medicines that both contain paracetamol, there's a risk of overdose.

These are not all the medicines that may cause problems if you take them with promethazine. For a full list, see the leaflet inside your medicine packet.

Taking promethazine with painkillers

It's safe to take promethazine with some painkillers, such as paracetamol or ibuprofen.

However, it's important to check the ingredients of your medicine carefully. This is because promethazine often comes mixed with a painkiller such as paracetamol.

If you take 2 medicines that both contain paracetamol, there's a risk of overdose. Speak to your pharmacist if you're not sure whether a medicine already contains a painkiller.

If you take promethazine with painkillers that contain codeine (such as co-codamol or other prescription painkillers), you may feel very tired and sleepy.

Do not drive, ride a bike or operate machinery or tools if this happens to you.

Mixing promethazine with herbal remedies and supplements

There might be a problem taking some herbal remedies and supplements alongside promethazine, especially ones that cause side effects such as sleepiness, a dry mouth or making it difficult to pee.

Ask your pharmacist for advice.

There's not enough information to say that other herbal remedies and supplements are safe to take with promethazine. They're not tested in the same way as pharmacy and prescription medicines. They're generally not tested for the effect they have on other medicines.