Ondansetron
Ondansetron is an antiemetic that prevents nausea and vomiting caused by chemotherapy, radiotherapy and surgery; it is sold as 4mg and 8mg Zofran tablets.
What ondansetron is for
Ondansetron is an antiemetic: it settles nausea and stops vomiting rather than treating the illness behind them. It is used to prevent sickness caused by chemotherapy, radiotherapy and surgery, and it also has a place in nausea from other causes. Timing does most of the work, with the first dose going in before the treatment starts so the reflex never builds. The tablets in this range are Zofran, 4mg and 8mg. Ondansetron is also made as a tablet that dissolves on the tongue and as a liquid, both for people who find swallowing tablets hard.
How it works
Serotonin is a messenger chemical with many jobs, and one of them is setting off the vomiting reflex when the gut or the brain is irritated. Ondansetron blocks one type of serotonin receptor, the 5-HT3 receptor, on nerve endings in the gut and in the vomiting centre of the brainstem. With those receptors occupied, the signal that would trigger retching and vomiting does not get through. It is not a sedative and it does not work like an antacid; it interrupts the specific pathway that chemotherapy, radiation and surgery switch on.
Taking the tablets
Swallow a tablet with water. Doses are arranged around the trigger, before chemotherapy or radiotherapy or before an operation, then repeated over the following day or days according to the treatment. Nothing needs to change about your usual diet. If a dose is forgotten it can be taken late, provided the next one is not already due; two doses are never taken together to catch up. Keep the tablets in the container they came in, closed, out of direct light and away from children.
Side effects
Headache and constipation are the ones people notice most, along with tiredness, drowsiness and the occasional chill; these tend to ease once the course ends. Serious effects are uncommon: a rash, or swelling of the face, lips or throat, difficulty breathing, chest pain, a fast or irregular heartbeat, blurred vision or vision loss, and fainting. A fever with stiff or twitching muscles, confusion, sweating or agitation is rare and needs urgent treatment.
Other medicines and ondansetron
Ondansetron can stretch the heart's electrical rhythm, and so can some antibiotics, antidepressants and heart medicines; used together the effect adds up. Low potassium or magnesium, heart failure and a family history of long QT syndrome (a rare heart rhythm problem) matter for the same reason. Medicines that raise serotonin, among them some antidepressants, triptans and tramadol, can increase the chance of the fever-and-muscle reaction described above.
Sources
- Ondansetron: MedlinePlus Drug Information — MedlinePlus / U.S. National Library of Medicine
- Ondansetron (oral route, oromucosal route) - Mayo Clinic — Mayo Clinic
Where can I order Ondansetron for delivery in Hong Kong?
Ondansetron can be ordered online for delivery to Hong Kong. The range includes generic Zofran, also sold as Ondansetron tablets, in 4mg and 8mg. A parcel that does not arrive within the delivery window, or arrives damaged, is sent again free, and if that is not possible the order is refunded.
What is the price of Ondansetron?
The ondansetron product has its own price per pack, shown on its page in HKD or your selected currency; larger packs usually cost less per unit.
Do I need a prescription to order Ondansetron?
PockDose does not ask you to upload a prescription when you order ondansetron. See the ordering FAQ for details.
What is another name for ondansetron?
Zofran is a brand name of ondansetron, which is also sold as Emeset, Ondem and Vomikind. Here, ondansetron can be bought online as generic Zofran. These are generics, not the original brand.
Is ondansetron the same as Zofran?
Yes, Zofran is one brand name for ondansetron, and the tablets here carry ondansetron as the only active ingredient. Anything sold under the plain name Ondansetron is the same medicine, just labelled by ingredient rather than by brand.
Does ondansetron stop vomiting that has already started?
It is mainly a preventive medicine, timed before chemotherapy, radiotherapy or surgery so that nausea never gets going. It is also used to treat nausea that has already begun, including nausea with causes other than those treatments.
How long do you take ondansetron for?
It depends on what is causing the sickness. After an operation it may be a single dose, while chemotherapy or radiotherapy is usually covered by doses spread across the days of treatment; the course ends when that treatment does.
What is the difference between the 4mg and 8mg tablets?
Only how much ondansetron each tablet holds. Both strengths are swallowed the same way and work in the same way; which one is used depends on what is being prevented and how long the course runs.