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Ondansetron (Zofran): Uses, Dosage, and Side Effects Explained
Summary of Key Points
Ondansetron, commonly known by its brand name Zofran, is a prescription medication used to prevent and treat nausea and vomiting caused by various conditions, such as chemotherapy, radiation therapy, surgery, and gastroenteritis. It works by blocking serotonin, a natural substance that can trigger nausea and vomiting. Ondansetron is available in multiple forms and strengths, making it adaptable for different treatment needs. Always consult your healthcare provider before adjusting your dose.
Names of Medication
US Brand Name: Zofran
Generic Name: Ondansetron
The generic name refers to the active ingredient in the medication, while the brand name is the name given by the manufacturer. In this case, the generic name is Ondansetron, and the brand name is Zofran.
Pharmacologic Category
5-HT3 Receptor Antagonist
Ondansetron belongs to a class of medications known as 5-HT3 receptor antagonists. These drugs work by blocking serotonin receptors in the brain and gut, which helps prevent nausea and vomiting. This mechanism makes Ondansetron an effective antiemetic for a variety of conditions.
Ondansetron Dosage
Ondansetron is prescribed for different conditions, and the dosage depends on the specific indication. Always follow your doctor’s instructions and consult with one of our telemedicine providers before making any changes to your dose.
Nausea and Vomiting
Adult Dose: 8 mg taken orally every 8 hours as needed. The duration of treatment depends on the underlying cause of nausea or vomiting.
Chemotherapy-Induced Nausea and Vomiting
Adult Dose: 8 mg taken orally 30 minutes before chemotherapy, followed by 8 mg every 8 hours for 1-2 days after chemotherapy. Ondansetron is commonly used for chemotherapy-induced nausea due to its effectiveness in blocking serotonin.
Radiation-Induced Nausea and Vomiting
Adult Dose: 8 mg taken orally 1-2 hours before radiation therapy, followed by 8 mg every 8 hours for 1-2 days after radiation.
Postoperative Nausea and Vomiting
Adult Dose: 16 mg taken orally 1 hour before anesthesia.
Gastroenteritis
Adult Dose: 8 mg taken orally every 8 hours as needed until symptoms resolve. Ondansetron is often used for nausea associated with gastroenteritis.
Hyperemesis Gravidarum (Severe Nausea in Pregnancy)
Adult Dose: 4-8 mg taken orally every 8 hours as needed. Consult your doctor before taking any medication during pregnancy, including Ondansetron.
Motion Sickness
Adult Dose: 8 mg taken orally 1 hour before travel, followed by 8 mg every 8 hours as needed.
Migraine-Associated Nausea
Adult Dose: 4-8 mg taken orally at the onset of nausea, repeated every 8 hours as needed.
Anesthesia-Related Nausea
Adult Dose: 4 mg taken orally or via IV 30 minutes before anesthesia, followed by 4 mg every 6-8 hours as needed.
Dosage Forms and Strengths
Ondansetron is available in several dosage forms and strengths to accommodate different patient needs:
- Oral Tablets: 4 mg, 8 mg
- Oral Disintegrating Tablets (ODT): 4 mg, 8 mg
- Oral Solution: 4 mg/5 mL
- Injectable Solution: 2 mg/mL (available in 2 mL and 20 mL vials)
Administration Instructions
Ondansetron can be taken with or without food. If using the oral disintegrating tablet (ODT), place it on your tongue and allow it to dissolve without water. For the oral solution, measure the dose carefully using a special measuring device or spoon. If you are receiving the injectable form, it will be administered by a healthcare professional. Always follow your healthcare provider’s instructions for proper use.
Ondansetron Side Effects and Adverse Reactions
Like all medications, Ondansetron can cause side effects. Most are mild, but some can be serious. If you experience any side effects, contact your healthcare provider immediately. You can also schedule a telemedicine appointment with one of our providers for guidance.
Common Side Effects (1-10%): Headache, fatigue, constipation, dizziness.
Less Common Side Effects (0.1-1%): Diarrhea, dry mouth, blurred vision.
Serious Side Effects (Rare): Heart rhythm changes (QT prolongation), severe allergic reactions (rash, itching, swelling), difficulty breathing.
Contraindications for Ondansetron
A contraindication is a specific situation where a medication should not be used because it may cause harm to the patient. For Ondansetron, there are certain conditions and factors that make it unsafe to take. Below is a list of contraindications for Ondansetron and explanations for why it is not recommended in these situations:
Allergy to Ondansetron or similar medications: If you have had an allergic reaction to Ondansetron or other serotonin 5-HT3 receptor antagonists (such as granisetron or dolasetron), taking it again could cause a severe allergic reaction, including rash, swelling, or difficulty breathing.
Congenital long QT syndrome: This is a heart condition that affects the electrical activity of the heart. Ondansetron can prolong the QT interval, which may increase the risk of a dangerous heart rhythm called Torsades de Pointes.
Severe liver disease: Ondansetron is metabolized by the liver. In patients with severe liver impairment, the drug may not be processed properly, leading to higher levels in the body and an increased risk of side effects.
Drug to Drug Interactions
Ondansetron can interact with other medications, potentially increasing side effects or reducing the effectiveness of either drug. Below are some medications that may interact with Ondansetron:
Amiodarone (Pacerone): This heart medication can raise the risk of abnormal heart rhythms when taken with Ondansetron.
Fluoxetine (Prozac): This antidepressant may increase the risk of serotonin syndrome, a potentially life-threatening condition, when combined with Ondansetron.
Rifampin (Rifadin): This antibiotic can reduce Ondansetron’s effectiveness by speeding up its metabolism in the liver.
Tramadol (Ultram): This pain medication can also increase the risk of serotonin syndrome when used with Ondansetron.
Phenytoin (Dilantin): This anti-seizure medication may reduce Ondansetron’s effectiveness by increasing its breakdown in the liver.
Ondansetron in Pregnancy
Is it Safe to Take Ondansetron During Pregnancy?
Ondansetron is sometimes prescribed during pregnancy to manage severe nausea and vomiting, such as in cases of hyperemesis gravidarum. While some studies suggest it may be safe, others raise concerns about a potential risk of birth defects, particularly when taken during the first trimester. It’s important to carefully weigh the benefits and risks with your healthcare provider. If you’re pregnant and considering Ondansetron, consult one of our telemedicine providers to discuss whether it’s the right option for you.
Ondansetron While Breastfeeding
Is it Safe to Take Ondansetron While Breastfeeding?
There is limited information on the safety of Ondansetron while breastfeeding. Small amounts of the drug may pass into breast milk, but it’s unclear if this could affect a nursing baby. If you’re breastfeeding, it’s essential to discuss the potential risks and benefits with your healthcare provider. Our telemedicine team can help you make an informed decision based on your individual circumstances.
Estimated Cost of Ondansetron
The cost of a 30-day supply of Ondansetron without insurance can vary depending on the pharmacy and location. With a GoodRX coupon, the estimated cost for a 30-day supply of generic Ondansetron (4 mg tablets) ranges from approximately $10 to $15. Brand-name Zofran is typically more expensive, with prices ranging from $150 to $200 for a 30-day supply.
Possible Alternatives to Ondansetron
If Ondansetron isn’t suitable for you, other treatments and lifestyle changes may help manage nausea and vomiting. Always consult your healthcare provider before making any changes to your treatment plan. Here are some alternatives based on specific conditions:
- Nausea and Vomiting: Alternatives include ginger supplements, acupressure wristbands, or other anti-nausea medications like metoclopramide (Reglan) or promethazine (Phenergan).
- Chemotherapy-induced nausea: Other medications such as aprepitant (Emend) or dexamethasone may be used. Non-drug options like acupuncture or relaxation techniques may also provide relief.
- Radiation-induced nausea: Medications like dexamethasone or metoclopramide may be alternatives. Eating small, frequent meals and avoiding spicy or fatty foods can also help.
- Postoperative nausea: Alternatives include scopolamine patches or dexamethasone. Staying hydrated and avoiding heavy meals before surgery may reduce nausea.
- Gastroenteritis: Staying hydrated and using over-the-counter medications like bismuth subsalicylate (Pepto-Bismol) may help. Ondansetron may be used in severe cases, but consult your provider first.
- Hyperemesis gravidarum: Vitamin B6 and doxylamine (Unisom) are often recommended as first-line treatments. Ginger and acupressure may also provide relief.
- Motion sickness: Alternatives include dimenhydrinate (Dramamine) or meclizine (Antivert). Non-drug options include focusing on the horizon or using acupressure wristbands.
- Migraine-related nausea: Anti-nausea medications like metoclopramide (Reglan) or prochlorperazine (Compazine) are often used. Managing migraine triggers through diet and stress reduction may also help.
- Anesthesia-related nausea: Alternatives include dexamethasone or scopolamine. Staying hydrated and avoiding heavy meals before surgery can also reduce the risk of nausea.
Recent Updates on Ondansetron Research
Recent research on Ondansetron has focused on its safety during pregnancy and its potential role in treating conditions beyond nausea and vomiting. A 2022 study examined its use in pregnant women and found no significant increase in the risk of birth defects, though more research is needed to confirm these findings. Additionally, ongoing studies are exploring Ondansetron’s use in treating opioid withdrawal symptoms and certain psychiatric conditions, such as anxiety and obsessive-compulsive disorder (OCD). While these studies are still in the early stages, they suggest Ondansetron may have broader applications in the future.
