Ondansetron (Zofran)

Brand Name - Zofran

  • Type of Drug: Antiemetic.
  • Prescribed for: Preventing nausea and vomiting that occurs after general anesthetics used during surgery and after certain cancer chemotherapy treatments.

Ondansetron (Zofran) General Information

Ondansetron and Granisetron produce their effect in a unique way. They antagonize the receptor for a special form of the neurohormone serotonin (5HT3). Receptors of this type are found in both the part of the brain that controls vomiting (the chemoreceptor trigger zone), and the vagus nerve in the stomach and intestines. Women absorb more Ondansetron faster than men and clear the drug more slowly from their bodies. This means that women will have more drug in their blood than men after taking the same dose of Ondansetron, but these differences have not been reflected in any difference in response to the drug.

Ondansetron and Granisetron are extremely effective in preventing nausea and vomiting and work in situations where many older antiemetics are ineffective.

Ondansetron (Zofran) Cautions and Warnings

Don’t take Ondansetron if you are allergic or sensitive to it.

People with liver failure must take less Ondansetron since the drug accumulates in their body and less is needed to produce the same effect.

Possible Side Effects

  • Most common: headache and constipation.
  • Less common: weakness, fever or chills, dry mouth, liver inflammation, diarrhea, abdominal pains, and rash.
  • Rare: liver failure, drug allergy, bronchial spasm, unusual tiredness or weakness, dizziness or lightheadedness, rapid heartbeat, angina pains, low blood potassium, and grand mal seizures.

Ondansetron (Zofran) Drug Interactions

• Ondansetron is broken down in the liver by the same enzyme system that is responsible for breaking down many other drugs. It may be affected by other drugs that stimulate or inhibit these enzymes, but no important interactions have been discovered to date.

Food Interactions

Food increases the amount of Ondansetron absorbed, but does not affect your Ondansetron dose.

Ondansetron (Zofran) Usual Dose

Adult and Adolescent (age 12 and older): 8 mg 3 times a day. People with liver failure should take no more than 8 mg a day.
Child (age 4-11): 4 mg 3 times a day.
Child (under age 4): not recommended.


Doses up to 145 mg have been taken without important side effects. Call your local poison control center or hospital emergency room for more information. If you go to the hospital for treatment, ALWAYS bring the medicine bottle with you.

Ondansetron (Zofran) Special Information

Call your doctor if you begin to have chest tightness, wheezing, trouble breathing, chest pains, or other unusual or severe side effects.

Ondansetron can cause dry mouth, which can increase your risk of tooth decay or gum disease. Pay special attention to oral hygiene while you are taking this drug.

If you forget to take a dose of Ondansetron, take it as soon as you remember. If it is almost time for your next dose, skip the dose you forgot and continue with the regular schedule. Skipping more than 1 dose may increase your chances of vomiting.

Ondansetron (Zofran) Special Populations

Studies of Ondansetron have revealed no potential to cause birth defects. Nevertheless, pregnant women should not take this, or any other, drug unless the possible risks and benefits to be gained from taking it have been discussed with their doctors.
Ondansetron may pass into breast milk. Nursing mothers who take this medicine should carefully observe for possible drug side effects in their infants.

Seniors may take this medicine without restriction.