Phenergan

What is Phenergan?

Phenergan is an anti-nausea medication that works to combat the symptoms of nausea and motion sickness. It’s often used to manage day-to-day travel sickness, and can also be taken to reduce the aftereffects of surgery, like vomiting and pain.

Nausea can have many different causes, including acid reflux, migraine, and food poisoning.^[1] Helping to identify the cause can help you to know which triggers to avoid, or recognise symptoms early when they begin.

Phenergan’s active ingredient, promethazine hydrochloride, is a type of drug called a phenothiazine. It works by blocking histamine, a chemical that your body overproduces during an allergic reaction. This means that as well as being an effective treatment against nausea, Phenergan is also used for reducing allergy symptoms.

How does Phenergan work?

Phenergan works by lowering the effects of histamine, changing the way the chemicals in your brain take action. Its active ingredient, promethazine, works by dulling the sensitivity of histamine receptors in the part of your brain associated with vomiting.

The tablets block these receptors without actually stopping the release of histamine. This stops the vomiting centre from becoming activated by inflammatory stimulus, and so this can help to reduce nausea and ease motion sickness.

What doses of Phenergan are there?

Phenergan comes in one dose of 25mg and is taken the night before your journey. An additional dose can be taken after six to eight hours if necessary. There used to be a 10mg and 20mg dose, but they are now discontinued.

How to take Phenergan

You should take Phenergan as instructed by your clinician, and in line with your patient information leaflet (PIL).

To take Phenergan:

• Take one tablet orally the night before your journey.
• Take it for no more than seven consecutive days.
• If needed, another dose can be taken six to eight hours after the first dose.

How long does it take Phenergan to work?

Phenergan is a quick and effective treatment for nausea, and your symptoms should reduce within 20 minutes of taking it and can last four to six hours^[1]

Don’t take more than the prescribed amount if your symptoms don’t feel like they’re getting better. Always remember to speak to your doctor or clinician for advice if you’re not sure about anything.

How long can I take Phenergan for?

Phenergan shouldn’t be taken for more than a period of seven days. If your symptoms haven’t improved within one week, you should speak to your clinician. They’ll advise you of what your next course of action should be.

What should I do if I make a mistake when taking Phenergan?

If you accidentally take more Phenergan than you’ve been advised to, then you should seek medical help as soon as possible. Don’t take an extra dose to make up for a forgotten dose. Instead, just take it when you remember or skip the missed dose if it’s close to the time your next one is due.