Ondansetron Vs. Meclizine: Drug Comparison

Meclizine is an over-the-counter and prescription medication used to prevent and treat motion sickness and dizziness associated with inner ear conditions like vertigo. It works by blocking certain signals in the brain that cause nausea, vomiting, and balance issues. Common side effects include drowsiness, dry mouth, and fatigue, so it is important to avoid driving or operating machinery until you know how it affects you. It should be used with caution in older adults and individuals with glaucoma, enlarged prostate, or respiratory conditions. Always follow the dosing instructions on the label, and avoid consuming alcohol while taking meclizine, as this can increase drowsiness.

Meclizine comes in different forms, including in a prescription form that is approved for the treatment of vertigo associated with diseases affecting the vestibular system in adults. The information below is about Meclizine 25, which is an over-the-counter version of meclizine.

Ondansetron is a medication used to prevent nausea and vomiting by blocking serotonin receptors in the brain and gut, which are involved in triggering the vomiting reflex. Its FDA-approved indications include the prevention of nausea and vomiting associated with chemotherapy, radiation therapy, and surgery. Off-label uses may include managing nausea in pregnancy (morning sickness) and gastroenteritis. Ondansetron is available in several forms, including oral tablets, orally disintegrating tablets, oral solution, and intravenous injections. Common side effects include headaches, constipation, and dizziness, while serious risks include a rare heart rhythm disorder (QT prolongation). Caution is advised in patients with heart conditions or those taking other medications that affect the QT interval.

Antihistamine

5-HT3 receptor antagonist

Meclizine 25 is used for prevention and treatment of these symptoms associated with motion sickness:

• Nausea

• Vomiting

• Dizziness

Ondansetron is indicated for the prevention of:

• Nausea and vomiting associated with highly emetogenic cancer chemotherapy, including cisplatin greater than or equal to 50 mg/m²

• Nausea and vomiting associated with initial and repeat courses of moderately emetogenic cancer chemotherapy

• Nausea and vomiting associated with radiotherapy in patients receiving either total body irradiation, single high-dose fraction to the abdomen, or daily fractions to the abdomen

• Postoperative nausea and/or vomiting

• Typically taken orally one hour before starting activity

• Comes in 25 mg tablets

• Typically taken orally—see the full prescribing information for the recommended dosage in adults and pediatric

• Comes in 4 mg, 8 mg, and 24 mg tablets

When using this product:

• Drowsiness may occur

• Avoid alcoholic drinks

• Alcohol, sedatives, and tranquilizers may increase drowsiness

• Be careful when driving a motor vehicle or operating machinery

The most common adverse reactions in adults for the:

Prevention of chemotherapy-induced (≥ 5%) are:

• Headache

• Malaise/Fatigue

• Constipation

• Diarrhea

Prevention of radiation-induced nausea and vomiting (≥ 2%) are:

• Headache

• Constipation

• Diarrhea

Prevention of postoperative nausea and vomiting (≥ 9%) are:

• Headache

• Low levels of oxygen

• Do not use for children under 12 years of age unless directed by a provider

• Drug interactions: Ask a provider or pharmacist before use if you are taking sedatives or tranquilizers

• Patients known to have hypersensitivity (e.g., anaphylaxis) to ondansetron or any components of the formulation

• Concomitant use of apomorphine

• Ask a doctor before use if you have:

  • Glaucoma

  • Difficulty in urination due to enlargement of the prostate gland

  • A breathing problem such as emphysema or chronic bronchitis

• Pregnancy: Ask health professional before use

• Breastfeeding: Ask health professional before use

• Hypersensitivity reactions, including anaphylaxis and bronchospasm

• QT interval prolongation and Torsade de pointes

• Serotonin syndrome

• Myocardial ischemia

• Masking of progressive ileus and/or gastric distension following abdominal surgery or chemotherapy-induced nausea and vomiting

*This information is from the Meclizine 25 label used by The Generic Pharmaceutical Company. See the Full Prescribing Information for more complete information. Meclizine may also be the active ingredient in other medications, and this information may not be accurate for all medications that include the active ingredient meclizine.

*This information is from the ondansetron hydrochloride label used by Aurobindo Pharma Limited. See the Full Prescribing Information for more complete information. This information may not be accurate for all medications that include the active ingredient ondansetron.