Domperidone and Ondansetron: Anti-Nausea Medicine Guide

6 min read · Medicines · By the Asthra Health Care team

What these medicines are used for

Nausea and vomiting are common with stomach infections, food poisoning, viral fevers, migraine, motion sickness and some medicines. Domperidone and ondansetron are two of the most frequently used anti-nausea medicines, also called antiemetics. They are useful when vomiting is so frequent that a person cannot keep down fluids, but they are not needed for every episode of mild nausea, which often settles with rest and small sips of fluid.

Doctors use ondansetron mainly for vomiting after surgery, during cancer treatment, and for short-term relief in stomach infections, including in children when vomiting stops them drinking ORS. Domperidone is used for short-term relief of nausea and vomiting and sometimes for bloating and fullness after meals. Neither treats the underlying cause, such as an infection, so the cause still needs attention.

• Vomiting from stomach infections or food poisoning
• Nausea after surgery or with cancer treatment (ondansetron)
• Short-term nausea and a feeling of fullness (domperidone)

How domperidone and ondansetron work

Domperidone blocks dopamine, a chemical messenger, in the gut and in the part of the brain that triggers vomiting. This helps the stomach empty faster and reduces the urge to vomit. It enters the brain very little, so it rarely causes the movement side effects seen with some older anti-nausea medicines.

Ondansetron blocks serotonin receptors in the gut and in the brain's vomiting centre. Serotonin is released in large amounts during chemotherapy and some infections, so blocking it is very effective at stopping vomiting. Ondansetron does not speed up the stomach.

Domperidone and ondansetron side effects: common and serious

Domperidone may cause dry mouth, headache, stomach cramps and, occasionally, breast swelling, milk discharge or menstrual changes, because it raises the hormone prolactin. Ondansetron commonly causes headache, constipation, tiredness and a warm or flushed feeling. Ondansetron can occasionally cause hiccups or dizziness. These effects are usually mild and short-lived.

The most important serious risk for both is an effect on heart rhythm, known as QT prolongation, which can rarely lead to dangerous irregular heartbeats. The risk with domperidone is higher in people over sixty and with higher amounts, which is why it is now recommended only for short courses. Allergic reactions can occur with either medicine.

Who should avoid them or take extra care

People with heart disease, heart failure, a known heart rhythm problem, a family history of sudden death, or low potassium or magnesium should speak to a doctor before using either medicine. Domperidone should be avoided in people with moderate or severe liver disease, and ondansetron needs caution in liver disease. Elderly people need extra care.

In pregnancy, doctors weigh the benefits carefully before prescribing either medicine, especially in the first three months, so never take them on your own if you are pregnant. Domperidone passes into breast milk. For children, these medicines should only be used on a doctor's advice. Babies with vomiting need to be seen by a doctor.

Domperidone and ondansetron interactions to know

Domperidone must not be taken with medicines that strongly slow its breakdown, such as ketoconazole, itraconazole, clarithromycin, erythromycin and some HIV medicines, as this raises heart-rhythm risk. Both medicines add to the heart-rhythm effect of other medicines that affect QT, including some antibiotics like azithromycin, some antidepressants, antipsychotics and certain heart rhythm medicines.

Ondansetron taken with some antidepressants or migraine medicines can rarely cause serotonin syndrome, with agitation, fever, sweating and muscle twitching. Ondansetron may also reduce the effect of tramadol. Water tablets that lower potassium can increase heart risk. Always tell your doctor or pharmacist about all your medicines.

Practical tips for using domperidone and ondansetron

Use these medicines only as your doctor prescribes or as your pharmacist advises, and only for a short time. Do not take them for weeks to hide ongoing nausea without finding the cause. Some forms melt on the tongue, which helps when swallowing is difficult.

Fluids matter more than anything else during vomiting. Take small, frequent sips of ORS, then move to light foods like rice kanji, curd rice or plain toast as you feel able. Rest and avoid strong smells. Prevent stomach infections with safe water, handwashing and freshly cooked food, especially during the monsoon.

When to talk to your doctor about domperidone and ondansetron

See a doctor if vomiting lasts more than a day, if you cannot keep any fluids down, or if there are signs of dehydration. Go urgently for vomiting blood, severe belly pain, a stiff neck, severe headache, palpitations or fainting. Ask your doctor or pharmacist which anti-nausea medicine, if any, is right for you.

This article is general health information, not medical advice. Do not start, stop or combine medicines on your own — always follow your doctor's prescription and ask your pharmacist if unsure.