Ondansetron HCl is a generic prescription drug that relieves nausea and vomiting in people undergoing traumatic medical procedures such as surgery, chemotherapy, or radiation therapy. Ondansetron HCl is the active ingredient in nearly all drugs labeled “ondansetron,” so the two names are used interchangeably. The only exceptions are some versions of ondansetron orally dissolving tablets. All ondansetron drugs block serotonin, a chemical that passes nerve signals in the nerves between the digestive system and the brain. Ondansetron doses are given by IV injection or by mouth.
Check our best Ondansetron prices
Ondansetron overview
BRAND NAMES:
No brand names are currently on the market
Generic Names:
Ondansetron, ondansetron HCl, ondansetron HCl dihydrate
Uses:
Prevents nausea and vomiting due to cancer treatment or surgical procedures
Therapeutic Classes:
Antiemetic, serotonin/5HT3 receptor antagonist
Forms:
Tablet, orally dissolving tablet, oral solution, injection
How it’s taken:
By mouth or intravenous injection
What is Ondansetron used for?
Ondansetron HCl prevents or reduces nausea and vomiting caused by medical procedures. It’s given to people before or after surgery or to cancer patients undergoing chemotherapy or radiation therapy.
What form(s) does Ondansetron come in
Tablet
4 mg
8 mg
24 mg
Orally disintegrating tablet
4 mg
8 mg
Oral solution (liquid)
4 mg/5 mL
Injection
2 mg/mL
What are common Ondansetron doses?
For the prevention of nausea and vomiting due to chemotherapy in adults:
For highly emetogenic (nausea-causing) chemotherapy: 0.15 mg/kg given as an IV injection three times every four hours OR one 24 mg oral dose given 30 minutes before chemotherapy
For moderately emetogenic (nausea-causing) chemotherapy: 0.15 mg/kg given as an IV injection in up to three doses given four or eight hours apart OR 8 mg taken by mouth 30 minutes before chemotherapy, 8 mg taken eight hours later, and 8 mg taken every 12 hours for one to two days
For the prevention of nausea and vomiting due to radiation therapy in adults:
For total body irradiation: 8 mg taken orally one to two hours before each fraction
For single high-dose fraction irradiation of the abdomen: 8 mg taken orally one to two hours before irradiation and 8 mg taken orally every eight hours for one to two days following irradiation
For daily fractionated irradiation of the abdomen: 8 mg taken orally one to two hours before irradiation and 8 mg taken orally every eight hours
Prevention of nausea and vomiting due to surgery in adults: 16 mg oral dose given one hour before anesthesia OR 4 mg IV injection given immediately before anesthesia (the injection can also be given within two hours after surgery if the patient has not received anti-nausea treatment and experiences nausea and vomiting)
Common Ondansetron prescriptions
Ondansetron HCl
50ml of 4mg/5ml bottleOndansetron HCl
3 tablets boxOndansetron HCl
4mg tabletOndansetron HCl
8mg tabletOndansetron HCl
20ml of 40mg/20ml vialOndansetron HCl
2ml of 4mg/2ml vial
How to take Ondansetron
Your doctor will tell you how much medicine to use. Do not use more than directed.
How to take ondansetron tablets:
Swallow the tablet whole with a glass of water. Do not cut or chew the tablet.
Store the tablets at room temperature.
How to take ondansetron orally disintegrating tablets:
Read the illustrated instructions for use on the back of the box before taking this medicine.
Do not remove the tablet until you are ready to take it.
Before removing a tablet, make sure your hands are dry.
DO NOT PUSH the tablet through the foil.
Instead, peel back the foil and gently remove the tablet from the blister pack.
Immediately place the tablet on the top of your tongue. Do not cut or chew the tablet.
It will dissolve in seconds.
Swallow the disintegrated tablet with saliva. You do not need to drink water or other liquids.
Ondansetron orally disintegrating tablets should be stored at room temperature, sealed in their blister pack, in the original carton.
How to take ondansetron oral solution:
Ondansetron oral solution does not need to be shaken before measuring out a dose.
When measuring a dose, use a calibrated oral syringe. If you don’t have one, a pharmacist can provide one at no cost.
Store ondansetron oral solution upright in the original bottle. Keep it at room temperature, protected from light.
What to do if you miss a dose of Ondansetron
If you miss a dose of ondansetron, take it when you can unless it’s almost time for the next dose. If that’s the case, skip the missed dose and take the regular dose as scheduled.
Do not take an extra dose to make up for a missed dose.
Ondansetron contraindications
This medicine is not right for everyone.
Ondansetron HCl should not be taken by anyone who has had an allergic reaction to ondansetron.
If you experience an allergic reaction after taking an ondansetron dose, stop taking the medicine and call the prescribing doctor immediately.
Ondansetron warnings
Tell any doctor or other healthcare provider who treats you that you are using this medicine.
Before taking ondansetron, make sure the doctor knows about all your medical conditions, particularly:
Liver problems
Heart problems
Congestive heart failure
Abnormal heartbeats
Low electrolyte levels
Stomach or bowel problems
Tell your doctor if you are pregnant or breastfeeding.
This medicine may cause heart rhythm abnormalities or other heart problems. Talk to a doctor if you experience any symptoms of heart problems, such as palpitations, slow heart rate, chest tightness, or chest pain.
Ondansetron orally dissolving tablets may contain aspartame. People with phenylketonuria (PKU) cannot safely take these products.
Ondansetron interactions
Many drugs can cause serious heart problems when combined with ondansetron, including commonly prescribed antibiotics, antiviral drugs, anticancer drugs, and drugs used to treat mental or mood disorders.
To prevent heart and other problems, the doctor prescribing ondansetron needs to know about all prescription drugs, over-the-counter medications, and supplements you use, especially:
Heart rhythm medications
Antidepressants or other drugs that treat mood disorders or mental illness
Antibiotics or antiviral drugs
Drugs that treat cancer
Anti-nausea drugs
Migraine medications called triptans
Seizure medications
Opioids, especially tramadol
The diabetes medication metformin
If taking ondansetron, always tell other healthcare providers you are using this medicine before they prescribe new medications.
Ondansetron can be taken with antacids.
Find out more about ondansetron interactions to avoid here.
Ondansetron side effects
Serious side effects
Talk to a doctor if you notice any signs or symptoms of a possible serious side effect, including:
Chest pain, chest tightness, shortness of breath, lightheadedness, fainting
Fast, pounding, or uneven heartbeat
Anxiety, restlessness, fast heartbeat, rigid muscles, flushing, sweating, disorientation, overactive reflexes
Trouble breathing
Slurred speech, involuntary eye rolling, twitching, grimacing
Vision changes
Blistering, peeling, red skin rash
Allergic reaction: Itching or hives, swelling in your face or hands, swelling or tingling in your mouth or throat, chest tightness, trouble breathing
Less serious side effects
Headache
Fatigue
Constipation
Diarrhea
Find more detailed information about Zofran (ondansetron) side effects here.
Sources:
Ondansetron hydrochloride injection prescribing information, DailyMed (NIH National Library of Medicine)
Ondansetron ondansetron hydrochloride solution prescribing information, DailyMed (NIH National Library of Medicine)
Ondansetron hydrochloride tablet prescribing information, DailyMed (NIH National Library of Medicine)
Ondansetron injection prescribing information, DailyMed (NIH National Library of Medicine)
Ondansetron orally disintegrating tablet prescribing information, DailyMed (NIH National Library of Medicine)
Subscribe to our savings newsletter
Health education, drug info, wellness & more
By clicking 'Subscribe', I agree to SingleCare's Terms & Conditions.
