Description
Indications
Ondansetron is a medication utilized to prevent nausea and vomiting triggered by cancer chemotherapy, radiation therapy, and surgical procedures. This medication belongs to a class of pharmaceuticals known as serotonin 5-HT3 receptor antagonists. Its mechanism of action involves the blocking of serotonin, a naturally occurring substance. Ondansetron operates in the stomach by impeding signals to the brain that cause nausea and vomiting.
Uses and Dosage
In order to prevent chemotherapy-induced nausea, ondansetron should be taken orally, usually within 30 minutes before treatment commences. To prevent nausea that arises from radiation treatment, take the medication orally 1 to 2 hours before the start of the treatment. To prevent nausea that occurs after surgery, take ondansetron by mouth 1 hour before surgery. It can be taken with or without food, although your doctor may instruct you not to eat before chemotherapy, radiation, or surgery.
When using the liquid form of this medication, use a specialized measuring device or spoon to accurately measure your prescribed dose. Avoid using a household spoon since you may not receive the correct dose.
Continue taking any other doses as prescribed by your doctor. Ondansetron may be taken up to three times per day for 1 to 2 days following chemotherapy or radiation treatment. If the medication is taken on a scheduled basis, take it at the same time each day to achieve the maximum benefit.
The dosage is based on your medical condition and how you respond to therapy. For children, the dosage may be based on their age and weight. The usual maximum dose for individuals with severe liver problems is 8 milligrams in 24 hours. Take this medication precisely as directed, without taking more or using it more frequently than prescribed.
Side Effects
Some side effects may occur that usually do not need medical attention:
- anxiety
- difficulty having a bowel movement
- dry mouth
- general feeling of discomfort or illness
- hyperventilation
- irritability
- shaking
- trouble sleeping
Inform your healthcare provider immediately if you experience any serious side effects:
- confusion
- dizziness
- fast heartbeat
- fever
- headache
- trouble breathing
- decrease in the urine volume
- difficulty with passing urine (dribbling)
- painful urination
decrease in the frequency of urination
Caution
Prior to taking ondansetron, inform your doctor or pharmacist if you have any allergies, particularly to this medication or other serotonin blockers such as granisetron, or to any other substances that may be present in the medication.
Before using this medication, disclose your medical history to your doctor or pharmacist, especially if you have a history of liver disease, irregular heartbeat, or stomach or intestinal problems such as recent abdominal surgery, ileus, or swelling.
Ondansetron has the potential to cause QT prolongation, which is a condition that affects heart rhythm. This could cause serious, occasionally fatal, fast or irregular heartbeat, and other symptoms such as severe dizziness or fainting that require immediate medical attention. The risk of QT prolongation may be increased in patients with certain medical conditions or who are taking other drugs that may cause QT prolongation.
Low levels of potassium or magnesium in the blood may also increase the risk of QT prolongation. This risk may be heightened by the use of certain drugs like diuretics or water pills.
Ondansetron may cause dizziness or drowsiness, which could be exacerbated by the consumption of alcohol or marijuana. Do not operate machinery, drive or do anything that requires alertness until it can be done safely.
To minimize the risk of dizziness and lightheadedness, rise slowly from a lying or sitting position.
If you are pregnant, ondansetron should only be used when necessary, as it may be harmful to an unborn baby. Consult with your doctor regarding the benefits and risks associated with this medication.
Consult with your doctor before breastfeeding if you are taking ondansetron.
Form and Strength
Zofran is available in the following forms and strengths:
-
ondansetron tablet:
- 4mg
- 8mg
FAQ
How long after taking Zofran do you feel better?
Zofran is quickly absorbed into your body. If you’re taking oral Zofran, it usually starts working within 30 minutes. However, it may take up to 2 hours to reach its full effects.
Can you still vomit on Zofran?
Yes, it’s possible for you to still feel nauseous and vomit even after taking ondansetron.
Resources
- https://www.goodrx.com/zofran/how-long-take-zofran-work
- https://www.goodrx.com/ondansetron/what-is
- https://medlineplus.gov/druginfo/meds/a601209.html
- https://www.webmd.com/drugs/2/drug-30/zofran-oral/details
- https://www.mayoclinic.org/drugs-supplements/ondansetron-oral-route-oromucosal-route/side-effects/drg-20074421
- https://www.drugs.com/zofran.html