Ondem 4: Uses, How It Works, Side Effects
Also known as: Ondem, Ondem 4 mg, Ondem 4 tablet, Ondansetron 4 mg, Ondem4
Ondem 4 is a prescription tablet containing 4 mg of ondansetron, used to prevent nausea and vomiting caused by chemotherapy, radiotherapy or surgery. It belongs to a group called 5-HT3 blockers. It is taken only on a doctor's advice. It can affect the heart's rhythm in some people, and it can cause constipation.
- Active ingredient
- Ondansetron 4 mg
- Type of medicine
- Antiemetics (anti-sickness medicines)
- Used for
- Nausea and vomiting
- Starts working in
- Usually within an hour of a dose; follow the timing your doctor gives
- Effect lasts
- Several hours; the medicine's half-life is about 6 hours, so doses are spaced out as prescribed
- With or without food
- Can be taken with or without food; follow the label or your doctor's advice
- Alcohol
- Alcohol can add to drowsiness and upset the stomach; ask your doctor
- Pregnancy
- Ask your doctor before taking it; studies in pregnancy are inconsistent
- Habit-forming
- No
- Made by
- VERIFY on pack
Pharmacist review in progress. This page is based on the sources listed below and is being checked by our registered pharmacist.
On this page
What is Ondem 4 used for?
Ondem 4 is a prescription medicine. It is used, on a doctor's advice, to prevent nausea and vomiting caused by cancer treatment and surgery.
- Preventing nausea and vomiting caused by chemotherapy
- Preventing nausea and vomiting caused by radiotherapy
- Preventing nausea and vomiting after surgery
How does Ondem 4 work?
Your body releases serotonin in the gut and the brain when you have chemotherapy, radiotherapy or surgery, and it triggers the urge to vomit through 5-HT3 receptors. Ondansetron blocks these receptors, so the sickness signal is reduced.
What happens in your body after you take it
You swallow the tablet
The tablet dissolves in the gut and ondansetron is absorbed into the blood. It can be taken with or without food.
It travels in the blood
Ondansetron is carried around the body and reaches the nerves of the gut and the part of the brain that controls vomiting.
It blocks 5-HT3 receptors
On the nerve endings in the gut and in the brain's vomiting centre, ondansetron attaches to the 5-HT3 receptor and stops serotonin from switching it on.
The urge to vomit is reduced
With the signal blocked, nausea and vomiting are less likely to start.
The liver clears it
Ondansetron is broken down mainly by the liver. Its half-life is about 6 hours in healthy people and longer in people with liver disease, which is why the dose may be limited in them.
How to take Ondem 4
Take Ondem 4 exactly as your doctor has prescribed or as printed on the pack. Your doctor decides the dose, the timing and how long you need it.
- For sickness linked to treatment, doctors usually give the first dose before the treatment. Follow the timing your doctor gives you.
- It can be taken with or without food. Follow the label or your doctor's advice.
- If you miss a dose, take it when you remember. If it is almost time for the next dose, skip the missed one. Do not take two doses together.
- If you vomit soon after taking it, or the sickness continues, ask your doctor before taking more.
- Liver disease may mean a lower maximum daily amount. Tell your doctor if you have liver problems.
Side effects of Ondem 4
Most people take ondansetron without serious problems. Some side effects are common and mild, but a few need medical help.
Uncommon or mild
- Headache
- Constipation
- Tiredness or weakness
- Diarrhoea
- Drowsiness
Rare but serious: get medical help
- Swelling of the face, lips, tongue or throat, rash or difficulty breathing (a severe allergic reaction). Get medical help immediately
- Fast, slow or irregular heartbeat, chest pain, dizziness or fainting
- Changes or loss of vision
- Agitation, confusion, seeing things that are not there, fever, heavy sweating, muscle stiffness or twitching, or loss of coordination (possible serotonin syndrome)
Who should be careful
Some people need to check with a doctor before taking Ondem 4, or need extra care while taking it.
When the label says not to use it
- Allergy to ondansetron or to any ingredient in the tablet
- Treatment with apomorphine, because the combination can cause a sharp drop in blood pressure and loss of consciousness
- Heart rhythm problems, long QT syndrome (in you or your family), heart failure or a slow heartbeat: ondansetron can change the heart rhythm
- Low potassium or magnesium, for example after vomiting or diarrhoea
- Liver disease: the medicine stays in the body longer
- Pregnancy: studies are inconsistent, so tell your doctor if you are pregnant or planning a pregnancy
- Breastfeeding: ask your doctor
- Allergy to ondansetron or similar medicines
- Vomiting that is severe, lasts long or has blood in it needs a doctor's check; an anti-sickness medicine can hide a problem that needs treatment
Medicines and things that interact with Ondem 4
Ondem 4 can interact with other medicines. Tell your doctor or pharmacist about everything you take, including herbal remedies.
- Apomorphine (used in Parkinson's disease): must not be combined, as it can cause a sharp drop in blood pressure and loss of consciousness
- Medicines that also affect heart rhythm, such as some antibiotics, antipsychotics and heart medicines: the risk of a heart rhythm problem rises
- SSRI and SNRI antidepressants, MAO inhibitors, tramadol and fentanyl: serotonin syndrome has been reported
- Phenytoin, carbamazepine and rifampicin: they may lower ondansetron levels
If someone takes too much
Taking one extra tablet by mistake is unlikely to be serious, but larger amounts can cause brief vision loss, dizziness, fainting, constipation and an irregular heartbeat. If someone has taken much more than prescribed, call 112 or go to the nearest hospital and take the medicine pack with you.
Storage
Store below 30 C in a dry place, protected from light and moisture, in the original pack, and out of the reach of children. Do not use after the expiry date. Check the pack for the exact storage instructions.
Regulatory status in India
Approved for sale in India as a prescription medicine. Single-ingredient ondansetron was not found on the CDSCO list of medicines banned under section 26A in the text checked for this batch. Ondem 4 contains ondansetron only.
Other brands with the same medicine
Ondansetron 4 mg is sold under other brand names and as generic medicines. They contain the same medicine; check the label for the strength and form. Do not switch between products without asking your doctor or pharmacist.
Other strengths and forms
Ondansetron is sold in different strengths and forms, including melt-in-mouth tablets, syrup and injection. The strength and form are printed on the pack, so check the label of the one you have.
Common questions
Is Ondem 4 a prescription medicine?
Yes. Ondansetron is a prescription medicine in India. It should be taken only if a doctor has prescribed it, and it should not be started, stopped or changed without the doctor's advice.
What is Ondem 4 used for?
It is used to prevent nausea and vomiting caused by chemotherapy, radiotherapy and surgery. A doctor may prescribe it in other situations. Do not use it for sickness you cannot explain; see a doctor if vomiting is severe or does not stop.
Can Ondem 4 affect the heart?
It can. Ondansetron may change the heart's rhythm, mainly in people with a heart rhythm problem, low potassium or magnesium, or those taking other medicines with the same effect. Tell your doctor about heart problems and all your medicines.
Does Ondem 4 cause constipation?
Yes, constipation is one of the common side effects. Drinking fluids and eating fibre may help. If it is severe or does not go away, tell your doctor or pharmacist.
Can I take Ondem 4 with food?
Yes. It can be taken with or without food. Follow the label or your doctor's advice about timing, which is often planned around treatment.
What should I do if I miss a dose of Ondem 4?
Take it when you remember. If it is almost time for the next dose, skip the missed one and carry on as usual. Never take two doses together to make up for a missed one.
What is the difference between Ondem 4 and Ondansetron 4 mg?
Ondem is a brand name, and ondansetron is the medicine inside it. Generic ondansetron 4 mg tablets contain the same active ingredient. Check the strength and ingredients on the pack, and ask your doctor before switching.
Sources
- Ondansetron tablets: prescribing information. DailyMed, US National Library of Medicine
- Ondansetron. MedlinePlus, US National Library of Medicine
- ATC/DDD Index: A04AA01 ondansetron. WHO Collaborating Centre for Drug Statistics Methodology
- Diarrhoea and vomiting. NHS (UK)
- List of drugs prohibited for manufacture and sale through gazette notifications under section 26A of the Drugs & Cosmetics Act 1940. Central Drugs Standard Control Organisation (CDSCO)