Ondansetron is used to treat nausea and vomitting. Ondansetron is in a class of medications called serotonin 5-HT3 receptor antagonists. It works by blocking the action of serotonin, a natural substance that may cause nausea and vomiting.¹

Ondansetron comes as a tablet and is typically taken by mouth every 12 hours for treatment of nausea and vomiting. Follow the directions on your prescription label carefully, and ask your doctor or pharmacist to explain any part you do not understand. Take ondansetron exactly as directed. Do not take more or less of it or take it more often than prescribed by your doctor.²

Ondansetron is typically taken by mouth every 12 hours.³

Most people will start to feel effects within about 30 minutes, with its strongest effect around one to two hours after a dose.⁴

Ondansetron is typically taken by mouth every 12 hours. Do not exceed your doctor’s recommended dose.⁵

Ondansetron can be prescribed to anyone age 4 or older. However, RedBox Rx only offers prescriptions to adults age 18 and older.⁶

RedBox Rx offers ondansetron tablets in 4 mg and 8 mg strength.

The maximum dose recommended is 24 mg per day, typically taken in two 12 mg doses.⁷

A single dose of ondansetron often helps control nausea for about four to 12 hours, depending on the person and the reason it is being used.⁸

With RedBox Rx, ondansetron costs a total of $64. This includes a one-time, online doctor consult for $39 and $25 for 20 ondansetron tablets.

Ondansetron is not available over the counter and requires a doctor’s prescription. Start your consult today.

Yes, ondansetron expires. Always properly dispose of unused, expired medication.

No, ondansetron should not be used during pregnancy.⁹

There doesn’t appear to be any harm, but more research is needed. Consult with your healthcare provider to be sure it’s safe for your family.¹⁰

Using this medicine with any of the following medicines is not recommended. Your doctor may decide not to treat you with this medication or change some of the other medicines you take.

• Apomorphine

• Bepridil

• Cisapride

• Dronedarone

• Ensitrelvir

• Fluconazole

• Ketoconazole

• Levoketoconazole

• Mavorixafor

• Mesoridazine

• Phenelzine

• Pimozide

• Piperaquine

• Posaconazole

• Saquinavir

• Sparfloxacin

• Terfenadine

• Thioridazine

• Tranylcypromine

• Ziprasidone

Using this medicine with any of the following medicines is usually not recommended, but may be required in some cases. If both medicines are prescribed together, your doctor may change the dose or how often you use one or both of the medicines.

• Abametapir

• Abiraterone Acetate

• Abiraterone Acetate, micronized

• Acecainide

• Adagrasib

• Alfentanil

• Alfuzosin

• Almotriptan

• Amineptine

• Amiodarone

• Amisulpride

• Amitriptyline

• Amitriptylinoxide

• Amoxapine

• Amphetamine

• Anagrelide

• Anileridine

• Apalutamide

• Aripiprazole

• Aripiprazole Lauroxil

• Arsenic Trioxide

• Artemether

• Asenapine

• Astemizole

• Atazanavir

• Avacopan

• Azathioprine

• Azimilide

• Azithromycin

• Bedaquiline

• Benzhydrocodone

• Benzphetamine

• Bretylium

• Brompheniramine

• Buprenorphine

• Bupropion

• Buspirone

• Butorphanol

• Capmatinib

• Carbamazepine

Using this medicine with cyclophosphamide may cause an increased risk of certain side effects, but using both drugs may be the best treatment for you. If both medicines are prescribed together, your doctor may change the dose or how often you use one or both of the medicines.¹¹

Ondansetron is not known to interact with alcohol, but caution is recommended. Ondansetron is prescribed to help prevent nausea and vomiting, and drinking alcohol can make these symptoms worse.

Also, ondansetron and alcohol can cause some similar side effects, such as headache. So you may be more likely to experience these side effects if you drink alcohol while taking ondansetron.¹²

Ondansetron can be taken with or without food.¹³

Before taking ondansetron:¹⁴

• Tell your doctor and pharmacist if you are allergic to ondansetron, alosetron (Lotronex), dolasetron (Anzemet), granisetron (Kytril), palonosetron (Aloxi, in Akynzeo), any other medications or any of the ingredients in ondansetron products. Ask your pharmacist for a list of the ingredients.

• Tell your doctor if you are receiving apomorphine (Apokyn). Your doctor will probably tell you not to take ondansetron if you are receiving this medication.

• Tell your doctor and pharmacist what prescription and nonprescription medications, vitamins, nutritional supplements and herbal products you are taking or plan to take. Be sure to mention any of the following: certain medications for seizures such as carbamazepine (Carbatrol, Epitol, Equetro, Tegretol) or phenytoin (Dilantin); clarithromycin (Biaxin, in Prevpac); erythromycin (E.E.S., Erythrocin, others); lithium (Lithobid); medications for irregular heartbeat; medications for mental illness; medications to treat migraines such as almotriptan (Axert), eletriptan (Relpax), frovatriptan (Frova), naratriptan (Amerge), rizatriptan (Maxalt), sumatriptan (Imitrex) and zolmitriptan (Zomig); methylene blue; mirtazapine (Remeron); monoamine oxidase (MAO) inhibitors, including isocarboxazid (Marplan), linezolid (Zyvox), phenelzine (Nardil), selegiline (Eldepryl, Emsam, Zelapar) and tranylcypromine (Parnate); moxifloxacin (Avelox); selective serotonin reuptake inhibitors (SSRIs) such as citalopram (Celexa), escitalopram (Lexapro), fluoxetine (Prozac, Sarafem, in Symbyax), fluvoxamine (Luvox), paroxetine (Brisdelle, Paxil, Pexeva) and sertraline (Zoloft). Your doctor may need to change the doses of your medications or monitor you more carefully for side effects. Many other medications may also interact with ondansetron, so be sure to tell your doctor about all the medications you are taking, even those that do not appear on this list.

• Tell your doctor if you or anyone in your family has or has ever had long QT syndrome (a condition that increases the risk of developing an irregular heartbeat that may cause fainting or sudden death) or another type of irregular heartbeat or heart rhythm problem,

• Tell your doctor if you have or have ever had low blood levels of magnesium or potassium in your blood, heart failure (HF; condition in which the heart cannot pump enough blood to other parts of the body) or liver disease.

• Tell your doctor if you are pregnant, plan to become pregnant or are breastfeeding. If you become pregnant while taking ondansetron, call your doctor.

• If you have phenylketonuria (PKU, an inherited condition in which a special diet must be followed to prevent mental retardation), you should know that the orally disintegrating tablets contain aspartame that forms phenylalanine.

Unless your doctor tells you otherwise, continue your usual diet.¹⁵

Take the missed dose as soon as you remember it. However, if it is almost time for the next dose, skip the missed dose and continue your regular dosing schedule. Do not take a double dose to make up for a missed one.¹⁶

Ondansetron may cause side effects. Tell your doctor if any of these symptoms are severe or do not go away:

• Headache

• Constipation

• Weakness

• Tiredness

• Chills

• Drowsiness

Some side effects can be serious. If you experience any of the following symptoms, call your doctor immediately or seek emergency medical treatment:

• Blurred vision or vision loss

• Rash

• Hives

• Itching

• Swelling of the eyes, face, lips, tongue, throat, hands, feet, ankles or lower legs

• Hoarseness

• Difficulty breathing or swallowing

• Chest pain

• Shortness of breath

• Dizziness, light-headedness or fainting

• Fast, slow or irregular heartbeat

• Agitation

• Hallucinations (seeing things or hearing voices that do not exist)

• Fever

• Excessive sweating

• Confusion

• Nausea, vomiting or diarrhea

• Loss of coordination

• Stiff or twitching muscles

• Seizures

• Coma (loss of consciousness)

Ondansetron may cause other side effects. Call your doctor if you have any unusual problems while you are taking this medication.¹⁷

It might, as feeling tired or sleepy is a side effect of ondansetron.¹⁸

It might, as constipation is a side effect of ondansetron.¹⁹

Yes, for some patients, ondansetron can help with stool consistency and with preventing an urgent need to go.²⁰

Keep this medication in the container it came in, tightly closed and out of reach of children. Store the tablets and rapidly disintegrating tablets away from light, at room temperature or in the refrigerator. Store the solution in the bottle upright at room temperature and away from light, excess heat and moisture (not in the bathroom).

It is important to keep all medication out of sight and reach of children, as many containers (such as weekly pill minders and those for eye drops, creams, patches and inhalers) are not child-resistant and young children can open them easily. To protect young children from poisoning, always lock safety caps and immediately place the medication in a safe location, out of their sight and reach. Learn more at http://www.upandaway.org.

Unneeded medications should be disposed of in special ways to ensure that pets, children and other people cannot consume them. However, you should not flush this medication down the toilet. Instead, the best way to dispose of your medication is through a medicine take-back program. Talk to your pharmacist or contact your local garbage/recycling department to learn about take-back programs in your community. See the FDA's Safe Disposal of Medicines website (http://goo.gl/c4Rm4p) for more information if you do not have access to a take-back program.²¹

In case of overdose, call the poison control helpline at 1-800-222-1222. Information is also available online at https://www.poisonhelp.org/help. If the victim has collapsed, had a seizure, has trouble breathing or can't be awakened, immediately call emergency services at 911.

Symptoms of overdose may include:²²

• Sudden loss of vision for a short time

• Dizziness or lightheadedness

• Fainting

• Constipation

• Irregular heartbeat

Keep all appointments with your doctor.

Do not let anyone else take your medication. Ask your pharmacist any questions you have about refilling your prescription.

It is important for you to keep a written list of all of the prescription and nonprescription (over-the-counter) medicines you are taking, as well as any products such as vitamins, minerals or other dietary supplements. You should bring this list with you each time you visit a doctor or if you are admitted to a hospital. It is also important information to carry with you in case of emergencies.²³

Ondansetron is the generic version of the brand name Zofran®.

In addition to ondansetron tablets, RedBox Rx offers the following FDA-approved prescription treatment options for nausea and vomiting:

• Ondansetron ODT (Generic Zofran®)

• Meclizine (Generic Antivert®)

• Metoclopramide (Generic Reglan®)

• Scopolamine Patch (Generic Transderm Scop®)

1. MedlinePlus

2. Mayo Clinic

3. Mayo Clinic

4. Drugs.com

5. Mayo Clinic

6. Mayo Clinic

7. FDA

8. Drugs.com

9. National Library of Medicine

10. Drugs.com

11. Mayo Clinic

12. Healthline

13. Drugs.com

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20. National Library of Medicine

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23. MedlinePlus