Dolasetron belongs to a group of medications called serotonin receptor antagonists. It is used to prevent nausea and vomiting associated with chemotherapy. It works by reducing the action of serotonin in the body. It is believed that serotonin is released by chemotherapy medications and causes nausea and vomiting as a result.

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 being given this medication, speak to your doctor. Do not stop using 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 use this medication if their doctor has not prescribed it.

The recommended adult dose of dolasetron in tablet form is 100 mg taken one hour before chemotherapy.

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 one above, do not change the way that you are using the medication without consulting your doctor.

Dolasetron may be taken with or without food. Swallow the tablets whole, with water.

It is very important to use this medication exactly as prescribed by your doctor. If you vomit a dose within an hour of taking it, take another tablet as soon as possible. If you miss a dose and you do not feel sick, take the next dose as scheduled. Do not take a double dose to make up for a missed one. If you are not sure what to do after missing a dose, contact your doctor or pharmacist for advice.

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

Do not take dolasetron if you:

• are allergic to dolasetron or any ingredients of the medication
• are a surgery patient (for the treatment or prevention of nausea after surgery)
• are under 18 years of age
• are being treated with the medication apomorphine

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.

• abdominal or stomach pain
• diarrhea
• dizziness or lightheadedness
• fever or chills
• headache
• unusual tiredness

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:

• increased or decreased blood pressure
• pain
• severe stomach pain with nausea or vomiting
• signs of heart problems (e.g., chest pain, fast heartbeat, slow or irregular heartbeat)
• signs of kidney problems (e.g., blood in the urine, decrease in the amount of urine, painful or difficult urination)
• swelling of feet or lower legs

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

• signs of a severe allergic reaction (e.g., difficulty breathing; skin rash; hives or itching; swelling of the eyelids, face, or lips)

Other side effects not listed above may occur in some people. Check with your doctor if you notice any symptom that worries you while you are taking this medication.

Before you begin taking 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 take this medication.

Abnormal heart rhythms: Dolasetron can cause changes to the rhythm of the heart, which may lead to serious complications, including death. If you have a condition that may make you more likely to develop heart rhythm changes, discuss with your doctor the risks and benefits of taking this medication.

You are more at risk for this type of abnormal heart rhythm and its complications if you:

• are female
• are older than 65 years of age
• have a family history of sudden cardiac death
• have a history of heart disease or abnormal heart rhythms
• have a slow heart rate
• have congenital prolongation of the QT interval
• have diabetes
• have had a stroke
• have low potassium, magnesium, or calcium levels
• have nutritional deficiencies
• are taking chemotherapy medications known as anthracyclines (e.g., doxorubicin, daunorubicin)
• are taking diuretics ("water pills")

If you have a history of heart disease, abnormal heart rhythms, or are taking medications to treat abnormal heart rhythms, 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.

Kidney function: Reduced kidney function may cause this medication to build up in the body, causing side effects. If you have kidney disease or reduced kidney 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. Your doctor may want to test your kidney function regularly with blood tests while you are taking this medication.

Liver function: Liver disease or reduced liver function may cause this medication to build up in the body, causing side effects. If you have liver problems, 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. Your doctor may want to test your liver function regularly with blood tests while you are taking this medication.

Pregnancy: 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 dolasetron passes into breast milk. If you are a breast-feeding mother and are 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 this medication have not been established for children.

Seniors: Seniors may be more likely to experience side effects related to irregular heart rhythm if they take dolasetron. This medication should be avoided by seniors.

There may be an interaction between dolasetron and any of the following:

If you are taking any of these 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. In many cases, interactions are intended or are managed by close monitoring. Speak to your doctor about how any drug interactions are being managed or should be managed.

Medications other than those listed above may interact with this medication. Tell your doctor or prescriber about all prescription, over-the-counter (non-prescription), and herbal medications that 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.