Domperidone (Motilium): anti-sickness medicine and heart warnings

Domperidone is an anti-sickness medicine that prevents nausea and vomiting. The NHS also notes two other uses under specialist direction: stomach pain in palliative or end-of-life care, and, when other measures have not worked, increasing breast milk supply, which is an off-label use.

It comes as tablets and as a liquid, and it is available on prescription only. The brand most patients recognise is Motilium.

Domperidone causes the muscles at the top of the stomach to tighten and those at the bottom to relax, which helps the stomach empty and makes vomiting less likely. It also blocks signals to the part of the brain that triggers vomiting.

The NHS says it should start to work in about 30 to 60 minutes and works best if taken before meals.

For adults and children aged 12 and over the NHS gives one 10 mg tablet, or 10 ml of liquid, up to three times a day, taken only when needed with at least 8 hours between doses. Take it 15 to 30 minutes before a meal or snack. Swallow tablets whole with water, and measure liquid with the oral syringe supplied rather than a kitchen teaspoon.

Because of the risk of heart rhythm problems with extended or high-dose use, it is usually prescribed for up to a week, and your doctor decides the shortest effective course.

• If you miss a dose and at least 2 hours remain before the next, take it now; otherwise skip it. Never double up.

• Taking too much can cause a fast or irregular heartbeat. Call NHS 111 if you exceed your dose, or 999 if you feel seriously unwell.

• It is usually best to use only one anti-sickness medicine at a time.

Most adults, and children aged 12 and over, can take it, and a specialist may prescribe it to younger children and babies. It is not suitable if you have had an allergic reaction to it or other medicines, weigh less than 35 kg, have a bowel blockage such as in Crohn's disease or diverticulitis, have had bleeding in the stomach or gut, have a pituitary gland tumour, or have liver, kidney or heart problems or an irregular heartbeat.

The NHS adds that domperidone may not suit people over 60, because the chance of side effects is higher.

Dry mouth is the most common effect, affecting more than 1 in 100 people. It is usually mild and goes away by itself, and sugar-free gum or sweets can help.

Call NHS 111 for unusual or uncontrolled eye or muscle movements or problems passing urine. Call 999 or go to A&E for a seizure, or a fast or irregular heartbeat. A serious allergic reaction, with swelling of the lips, mouth, throat or tongue, breathing difficulty or collapse, also needs 999. Suspected effects can be reported through the Yellow Card scheme.

Domperidone can be taken in pregnancy if other anti-sickness medicines have not worked. It can be used while breastfeeding if a doctor confirms the baby is healthy, preferably short-term; only trace amounts reach milk and there is a long history of use without documented harm to babies. No evidence suggests it affects fertility.

The NHS asks you to tell a prescriber if you take antidepressants or antipsychotics, antibiotics or antifungals, antimalarials, HIV medicines, heart or blood pressure medicines, or cancer treatments, since several of these can affect heart rhythm too.

It is best to avoid alcohol, which can add to sleepiness and irregular heartbeat. If domperidone makes you sleepy or your heartbeat feels irregular, do not drive or cycle; you are responsible for judging whether it is safe. Apart from alcohol, you can eat and drink normally.

Metoclopramide and cyclizine are other anti-sickness medicines, each with its own guide.