Generic name: ondansetron (injection) [ on-DAN-se-tron ]
Brand name: Zofran
Dosage forms: injectable solution (2 mg/mL), intravenous solution (32 mg/50 mL-D5%)
Drug class: 5HT3 receptor antagonists
What is ondansetron?
Ondansetron blocks the actions of chemicals in the body that can trigger nausea and vomiting.
Ondansetron is used to prevent nausea and vomiting that may be caused by surgery or by medicine to treat cancer (chemotherapy).
Ondansetron may be used for purposes not listed in this medication guide.
You should not use ondansetron if you are also using apomorphine (Apokyn).
Before taking this medicine
You should not use ondansetron if you are allergic to ondansetron, or if you are also using apomorphine (Apokyn).
To make sure ondansetron is safe for you, tell your doctor if you have:
heart disease, congestive heart failure, a heart rhythm disorder;
an electrolyte imbalance (such as low levels of potassium or magnesium in your blood);
a personal or family history of Long QT syndrome; or
a condition for which you take a diuretic or "water pill."
Ondansetron is not expected to harm an unborn baby. Tell your doctor if you are pregnant.
It is not known whether ondansetron passes into breast milk or if it could harm a nursing baby. Tell your doctor if you are breast-feeding a baby.
How is ondansetron given?
Ondansetron is injected into a vein through an IV. A healthcare provider will give you this injection.
Ondansetron is usually given just before your surgery begins, or within 2 hours after surgery.
To prevent nausea and vomiting caused by chemotherapy, ondansetron is given 30 minutes before the start of chemotherapy. A second and third dose of ondansetron are sometimes given 4 hours and 8 hours after the first dose.
What happens if I miss a dose?
Because you will receive ondansetron in a clinical setting, you are not likely to miss a dose.
What happens if I overdose?
Since ondansetron is given by a healthcare professional in a medical setting, an overdose is unlikely to occur.
What should I avoid after receiving ondansetron?
This medicine may cause blurred vision and may impair your thinking or reactions. Be careful if you drive or do anything that requires you to be alert and able to see clearly.
Ondansetron side effects
Get emergency medical help if you have any of these signs of an allergic reaction: rash, hives; fever, chills, difficult breathing; swelling of your face, lips, tongue, or throat.
Ondansetron may cause serious side effects. Call your doctor at once if you have:
headache with chest pain and severe dizziness, fainting, fast or pounding heartbeats;
blurred vision or temporary vision loss (lasting from only a few minutes to several hours);
severe constipation, stomach pain, or bloating;
a light-headed feeling, like you might pass out;
little or no urination; or
high levels of serotonin in the body--agitation, hallucinations, fever, fast heart rate, overactive reflexes, nausea, vomiting, diarrhea, loss of coordination, fainting.
Common side effects of ondansetron may include:
diarrhea or constipation;
This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.
What other drugs will affect ondansetron?
Ondansetron can cause a serious heart problem, especially if you use certain medicines at the same time, including antibiotics, antidepressants, heart rhythm medicine, antipsychotic medicines, and medicines to treat cancer, malaria, HIV or AIDS. Tell your doctor about all medicines you use, and those you start or stop using during your treatment with ondansetron.
Receiving ondansetron while you are using certain other medicines can cause high levels of serotonin to build up in your body, a condition called "serotonin syndrome," which can be fatal. Tell your doctor if you also use:
medicine to treat depression;
medicine to treat a psychiatric disorder;
a narcotic (opioid) medication; or
medicine to prevent nausea and vomiting.
This list is not complete and many other drugs can interact with ondansetron. This includes prescription and over-the-counter medicines, vitamins, and herbal products. Give a list of all your medicines to any healthcare provider who treats you.
How long before a meal should you take ondansetron?
If you are taking ondansetron for nausea that occurs with meals, then the standard tablet should be taken half an hour to 1 hour before meals, and the orally disintegrating tablet or oral soluble film can be taken 15 minutes before meals. However, if you are taking ondansetron for constant, all day nausea then it should be taken at regular intervals during the day as prescribed, with or without food.
How long does ondansetron take to work?
Oral ondansetron works quickly, usually within 30 minutes, but it can take up to two hours for the full effect. It’s taken before you receive medicines or procedures that might make you feel nauseous or cause vomiting. Oral doses are usually taken 30 minutes before chemotherapy, 1 hour before surgery, or 1 to 2 hours before radiation treatments. You may need extra doses. Your doctor will tell you exactly when to take your medication.
How often can you take ondansetron?
You can take ondansetron more frequently initially, for example, if you are taking it to prevent or treat nausea of vomiting from chemotherapy you can take 4mg then follow up with another 4mg dose at 4 and 8 hours after the first dose. The following day you should only take it every 8 hours (3 times a day). If you continue taking ondansetron more frequently than this you are at higher risk of side effects such as constipation, headache, or heart effects.
Does ondansetron make you sleepy?
Yes, ondansetron (Zofran) might make you feel sleepy or tired. Ondansetron injection for the treatment of post-operative nausea and vomiting has been reported to cause drowsiness or sedation in 8% of patients vs. 7% of those using a placebo (an inactive treatment). Malaise (generally feeling unwell) and fatigue (tiredness or lack of energy) have also been reported in 13% of patients (vs. 2% placebo) when it is used orally for the prevention of chemotherapy-induced nausea and vomiting.
Although ondansetron is not specifically approved by the FDA to treat nausea and vomiting during pregnancy (NVP), its use is common, and approximately 25% of pregnant women are prescribed ondansetron to treat NVP. Overall, studies show the use of ondansetron appears to be associated with an additional 3 instances of oral cleft defects (such as cleft lip or cleft palate) for every 10,000 women exposed to ondansetron during their first trimester. There may also be a very slight increased risk of a type of heart defect called a ventricular septal defect, but no apparent increased risk of other birth defects, miscarriage, or fetal death. Continue reading
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