Meclizine

What is Meclizine?

Meclizine is an antihistamine tablet that treats nausea. It can also ease dizziness and vomiting caused by motion sickness.^[1]

Antihistamines block histamine, a chemical that is released as an immune response. Usually, your body produces histamine in response to allergens or pathogens it perceives to be a threat. For some people, the release of histamine can make them feel sick. By blocking it, Meclizine can ease nausea symptoms.

How does Meclizine work?

Meclizine blocks H1 histamine receptors in your brain, reducing the effects of histamine. This can help stop nausea symptoms when they start, but Meclizine can also be used to prevent them. The tablets can be taken ahead of travelling to stop motion sickness during your journey, or in advance of being exposed to a known nausea trigger, such as certain foods.

Specifically, Meclizine belongs to a class of antihistamines called piperazines. Unlike other antihistamines that are used to treat allergies, it has an antiemetic action, meaning it can prevent nausea and vomiting.

What doses of Meclizine are there?

Meclizine tablets are available in two strengths: 12.5mg and 25mg.

The usual dose is one tablet before or as you’re experiencing nausea symptoms. Usually, you’ll be prescribed a dose of 25mg or 50mg to take about an hour before travelling. You might be prescribed more if a physician thinks it will help to improve your symptoms.

You might be started on the lowest dose Meclizine tablet to see if it improves your nausea symptoms. If you feel like you need a higher dose, you speak to your physician about changing.

How to take Meclizine

Swallow your tablets whole, with a drink of water. Avoid chewing, crushing, or breaking the tablets in half.

If you’re taking Meclizine for motion sickness, you should take it around an hour before you travel. This gives the tablet a chance to work before nausea symptoms start during your journey.

Meclizine might make you drowsy, so this is something to consider before taking your tablet. Avoid driving or operating machinery before you know how Meclizine makes you feel.

How long does Meclizine take to work?

Meclizine usually takes about an hour to start working. This is why it’s recommended you take it an hour before travelling when using the tablets to treat motion sickness.

Medications affect people differently, so you might find Meclizine starts working sooner than this. Meclizine has a half-life of 5-6 hours, which is the time the concentration of the medication takes to reduce by half.^[1] This means a single dose can be long-lasting and might reduce nausea symptoms over several hours.

What if I make a mistake while using Meclizine?

Take your tablets how you’ve been advised to by your prescriber. For nausea, you’ll usually need a dose before travelling, or to ease symptoms you start to feel sick.

If you forget to take a tablet when you normally would, you can take it as soon as you remember. There’s never any need to take more than one tablet at a time. Doubling your dose won’t make Meclizine work more effectively, and could cause unpleasant side effects.

If you swallow more tablets than you should for any reason, go to your nearest hospital and get urgent help at their emergency department.