Ondansetron is a prescription drug that is used to combat nausea, vomiting, and related symptoms that arise after chemotherapy treatment. Patients who undergo some types of surgeries may also be given the drug before their procedures to prevent complications afterward. The medication works by blocking the activity of the neurotransmitter serotonin in the nervous system, which stops the vomiting reflex. Ondansetron may be given in oral or intravenous doses that are carefully measured by a health-care professional. The risks of side effects are generally low, though a small number of patients may experience adverse effects or allergic reactions that require prompt medical attention.
Antinausea drugs such as ondansetron block serotonin receptor sites in the brain and throughout the intestinal tract. When serotonin cannot bind to its receptors in the intestines, nerve cells cannot induce the small muscle contractions that would normally cause a vomiting reflex and stomach upset. Nausea and vomiting can be major problems for cancer patients who undergo chemotherapy treatments, and ondansetron is highly effective at preventing such unpleasant side effects. The drug is also used before or immediately after surgical procedures in order to ensure patient comfort and avoid complications from the physical act of vomiting.
In most cases, ondansetron is administered through an intravenous line about half an hour before a round of chemotherapy. Boosters of oral or intravenous ondansetron are often given four and eight hours after the initial dose. In order to prevent nausea associated with surgery, patients are usually given intravenous doses shortly before receiving anesthesia. The drug may also be given after surgery if nausea and vomiting symptoms arise. The exact amounts of the medication used depend on many factors, including the age of the patient, the type of chemotherapy drugs used, and his or her overall health condition.
The most common side effects when using ondansetron include weakness, drowsiness, mild headaches, and constipation. Rarely, the drug may induce muscle spasms, chest pains, vision changes, and anxiety. An allergic reaction might cause a person to break out in itchy hives, become lightheaded and dizzy, and have swelling in the airways that makes it difficult to take deep breaths. Major side effects and reactions should be reported to a doctor right away so they can be treated properly. Most people who use ondansetron do not experience significant side effects, but if complications do occur there are a few alternative medications that a doctor can try to see if the response is any better.