5HT3 Antagonists

Other names: Palonosetron (Aloxi®), Ondansetron (Zofran®), Dolasetron (Anzemet®), Granisetron (Kytril®)

About This Drug

5-HT3 Receptor Antagonists are medications that are used before and after chemotherapy to prevent or treat nausea or vomiting. These medications may be given in the vein (IV), as an oral tablet by mouth, as an oral disintegrating tablet, or as a patch.

Possible Side Effects

  • Constipation (not being able to move bowels)
  • Loose bowel movements (diarrhea)
  • Headache
  • Feeling dizzy
Note: Not all possible side effects are included above.

Warnings and Precautions 

  • Abnormal heart beat and/or abnormal EKG
  • Allergic reactions, including anaphylaxis are rare but may happen in some patients. Signs of allergic reaction to this drug may be swelling of the face, feeling like your tongue or throat are swelling, trouble breathing, rash, itching, fever, chills, feeling dizzy, and/or feeling that your heart is beating in a fast or not normal way. If this happens, do not take another dose of this drug. You should get urgent medical treatment.

How to Take Your Medication

  • Please refer to the package insert for the specific medicine you are taking for information on how to take your medicine.

Treating Side Effects

  • Ask your doctor or nurse about medicines that are available to help stop or lessen constipation.
  • If you are not able to move your bowels, check with your doctor or nurse before you use enemas, laxatives, or suppositories
  • Drink plenty of fluids (a minimum of eight glasses per day is recommended).
  • If you have loose bowel movements, you should drink more fluids so that you do not become dehydrated (lack water in the body from losing too much fluid). 
  • If you get diarrhea, eat low-fiber foods that are high in protein and calories and avoid foods that can irritate your digestive tracts or lead to cramping. 
  • Ask your nurse or doctor about medicine that can lessen or stop your diarrhea.
  • Keeping your pain under control is important to your well-being. Please tell your doctor or nurse if you are experiencing a headache.
  • If you are dizzy, get up slowly after sitting or lying.

Food and Drug Interactions

  • There are no known interactions of 5HT3 with food.
  • These drug may interact with other medicines. Tell your doctor and pharmacist about all the medicines and dietary supplements (vitamins, minerals, herbs and others) that you are taking at this time. 

When to Call the Doctor

Call your doctor or nurse if you have any of these symptoms and/or any new or unusual symptoms:

  • Feeling that your heart is beating in a fast or not normal way (palpitations)
  • No bowel movement in 3 days or when you feel uncomfortable
  • Loose bowel movements (diarrhea) 4 times a day or loose bowel movements with lack of strength or a feeling of being dizzy
  • Headache that does not go away
  • Feeling dizzy or lightheaded
  • Signs of allergic reaction: swelling of the face, feeling like your tongue or throat are swelling, trouble breathing, rash, itching, fever, chills, feeling dizzy, and/or feeling that your heart is beating in a fast or not normal way

Production Warnings

  • Pregnancy warning: These drugs are not expected to harm an unborn child.  Talk to your doctor about the use of this drug if you are pregnant or plan to become pregnant.
  • Breastfeeding warning: It is not known if these drugs passes into breast milk.  For this reason, women should talk to their doctor about the risks and benefits of breast feeding during treatment with these drugs because this drug may enter the breast milk and cause harm to a breast feeding baby.
  • Fertility warning: These drugs are not expected to affect your ability to have children in the future. Human fertility studies have not been done with this drug.

Revised July 2017