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How does this medication work? What will it do for me?

Palonosetron belongs to the class of medications called 5-HT3 receptor antagonists. This medication is used to prevent nausea and vomiting associated with certain types of cancer chemotherapy. It works by reducing the effects of a naturally occurring chemical in the body called serotonin, which causes nausea and vomiting.

This medication may be available under multiple brand names and/or in several different forms. Any specific brand name of this medication may not be available in all of the forms or approved for all of the conditions discussed here. As well, some forms of this medication may not be used for all of the conditions discussed here.

Your doctor may have suggested this medication for conditions other than those listed in these drug information articles. If you have not discussed this with your doctor or are not sure why you are taking this medication, speak to your doctor. Do not stop taking this medication without consulting your doctor.

Do not give this medication to anyone else, even if they have the same symptoms as you do. It can be harmful for people to take this medication if their doctor has not prescribed it.

How should I use this medication?

Injection: The recommended adult dose is 0.25 mg given as an injection into the vein (intravenous) over 30 seconds, and about 30 minutes before you get your anticancer medicine (chemotherapy). The recommended dose for children is based on body weight and is given as an intravenous infusion over 15 minutes, starting about 30 minutes before the chemotherapy.

Capsule: The recommended adult dose is 0.5 mg (one capsule) by mouth about an hour before you get your anticancer medicine (chemotherapy). Palonosetron can be taken with or without food.

Many things can affect the dose of medication that a person needs, such as body weight, other medical conditions, and other medications. If your doctor has recommended a dose different from the ones listed here, do not change the way that you are taking the medication without consulting your doctor.

It is important to take this medication exactly as prescribed by your doctor. If you miss a dose, let your doctor know as soon as possible.

Store this medication at room temperature, and keep it out of the reach of children.

What form(s) does this medication come in?


Every 5 mL of clear, colourless solution in glass vials contains 0.25 mg of palonosetron (as hydrochloride). Nonmedicinal ingredients: mannitol, disodium edetate, and citrate buffer in water.


Each light beige, opaque, soft gelatin capsule, contains palonosetron (free base) 0.5 mg. Nonmedicinal ingredients: monoglycerides and diglycerides of capryl/capric acid, gelatin, sorbitol, glycerin, water, polyglyceryl oleate, titanium dioxide, butylated hydroxyanisole, and black printing ink. May contain traces of medium chain triglyceride and lecithin.

Who should NOT take this medication?

Do not use this medication if you are allergic to palonosetron or any of the other ingredients in the injection or capsule.

What side effects are possible with this medication?

Many medications can cause side effects. A side effect is an unwanted response to a medication when it is taken in normal doses. Side effects can be mild or severe, temporary or permanent.

The side effects listed below are not experienced by everyone who takes this medication. If you are concerned about side effects, discuss the risks and benefits of this medication with your doctor.

The following side effects have been reported by at least 1% of people taking this medication. Many of these side effects can be managed, and some may go away on their own over time.

Contact your doctor if you experience these side effects and they are severe or bothersome. Your pharmacist may be able to advise you on managing side effects.

  • constipation
  • fatigue
  • headache

Although most of the side effects listed below don't happen very often, they could lead to serious problems if you do not check with your doctor or seek medical attention.

Check with your doctor as soon as possible if any of the following side effects occur:

  • abdominal pain

Stop taking the medication and seek immediate medical attention if any of the following occur:

  • symptoms of a severe allergic reaction (such as hives; rash; difficulty breathing or swallowing; or swelling of the face, lips, tongue, or throat)
  • symptoms of serotonin syndrome (e.g., confusion, fast heartbeat, hallucinations, restlessness, shaking, shivering, sudden jerking of muscles, sweating)

Some people may experience side effects other than those listed. Check with your doctor if you notice any symptom that worries you while you are taking this medication.

Are there any other precautions or warnings for this medication?

Before you begin using a medication, be sure to inform your doctor of any medical conditions or allergies you may have, any medications you are taking, whether you are pregnant or breast-feeding, and any other significant facts about your health. These factors may affect how you should use this medication.

Drowsiness/reduced alertness: Palonosetron may cause drowsiness or dizziness, affecting your ability to drive or operate machinery. Avoid driving, operating machinery, or performing other potentially hazardous tasks until you have determined how you are affected by this medication.

Heart rhythm: Very rarely, palonosetron can affect the heart's electrical activity and cause an abnormal heart rhythm called QT prolongation. If you have heart problems (e.g., an irregular heartbeat, QT prolongation) or a family history of QT prolongation or sudden cardiac death before the age of 50, discuss with your doctor how this medication may affect your medical condition, how your medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed. If you are taking other medications that can also affect heart rhythm, tell your doctor before using palonosetron.

Liver function: Palonosetron is broken down and removed from the body by the liver. Decreased liver function slows down the removal of the medication from the body and increases the risk of side effects from palonosetron. If you have liver disease or reduced liver function, discuss with your doctor how this medication may affect your medical condition, how your medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed.

Neuroleptic malignant syndrome (NMS): Palonosetron, like other similar medications, can cause a potentially fatal syndrome known as neuroleptic malignant syndrome (NMS). If you notice the symptoms of NMS such as high fever, muscle stiffness, confusion or loss of consciousness, sweating, racing or irregular heartbeat, or fainting, get immediate medical attention.

Serotonin syndrome: Severe reactions are possible when palonosetron is combined with other medications that act on serotonin, such as tricyclic antidepressants and serotonin reuptake inhibitors, medications used to treat depression. These combinations should be avoided. Symptoms of a reaction may include muscle rigidity and spasms, difficulty moving, or changes in mental state including delirium, agitation, unconsciousness, and coma.

Pregnancy: The safety of palonosetron for use by pregnant people has not been established. This medication should not be used during pregnancy unless the benefits outweigh the risks. If you become pregnant while taking this medication, contact your doctor immediately.

Breast-feeding: It is not known if palonosetron passes into breast milk. If you are breast-feeding and taking this medication, it may affect your baby. Talk to your doctor about whether you should continue breast-feeding.

Children: The safety and effectiveness of using palonosetron capsules have not been established for children under 18 years of age. The safety and effectiveness of using palonosetron injection have not been established for children under the age of 2 years.

What other drugs could interact with this medication?

For a full list of interactions, use the Drug Interaction Checker available on the Drugs.com website.

If you are taking other medications, speak with your doctor or pharmacist. Depending on your specific circumstances, your doctor may want you to:

  • stop taking one of the medications,
  • change one of the medications to another,
  • change how you are taking one or both of the medications, or
  • leave everything as is.

An interaction between two medications does not always mean that you must stop taking one of them. Speak to your doctor about how any drug interactions are being managed or should be managed.

Tell your doctor or prescriber about all prescription, over-the-counter (non-prescription), and herbal medications you are taking. Also tell them about any supplements you take. Since caffeine, alcohol, the nicotine from cigarettes, or street drugs can affect the action of many medications, you should let your prescriber know if you use them.

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