Trimethobenzamide is used to treat nausea and vomiting that may occur after surgery. It is also used to control nausea caused by gastroenteritis (‘stomach flu’; a virus that may cause nausea, vomiting, and diarrhea). Trimethobenzamide is in a class of medications called antihistamines. Trimethobenzamide may work by decreasing activity in the area of the brain that causes nausea and vomiting.

Side Effects Of Trimethobenzamide

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

  • drowsiness
  • dizziness
  • headache
  • depression
  • diarrhea

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

  • rash
  • backward arching of the head, neck, and back
  • muscle cramps
  • uncontrollable shaking of a part of the body
  • slow, jerking movements
  • shuffling walk
  • slow speech
  • confusion
  • blurred vision
  • yellowing of the skin or eyes
  • seizures
  • coma (loss of consciousness for a period of time)

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

Warnings & Precautions

Before taking trimethobenzamide:

  • tell your doctor and pharmacist if you are allergic to trimethobenzamide or any other medications.
  • 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: antidepressants; antihistamines; barbiturates such as phenobarbital (Luminal); belladonna alkaloids (Donnatal); medications for anxiety, mental illness, pain, and seizures; other medications for nausea and vomiting; sedatives; sleeping pills; and tranquilizers. Your doctor may need to change the doses of your medications or monitor you more carefully for side effects.
  • tell your doctor if you have Reye’s Syndrome (a condition affecting the brain and liver that can happen after a viral illness), encephalitis (inflammation of the brain), or a high fever, or if you have or have ever had liver disease. If you will be giving trimethobenzamide to a child, also tell the child’s doctor if the child has any of the following symptoms before he or she receives the medication: vomiting, listlessness, drowsiness, confusion, aggression, seizures, yellowing of the skin, or eyes, weakness, or flu-like symptoms. Also tell the child’s doctor if the child has not been drinking normally, has had excessive vomiting or diarrhea, or appears dehydrated.
  • tell your doctor if you are pregnant, plan to become pregnant, or are breast-feeding. If you become pregnant while taking trimethobenzamide, call your doctor.
  • if you are having surgery, including dental surgery, tell the doctor or dentist that you are taking trimethobenzamide.
  • you should know that this medication may make you drowsy. Do not drive a car or operate machinery until you know how this medication affects you.
  • ask your doctor about the safe use of alcoholic beverages while you are taking trimethobenzamide. Alcohol can make the side effects of trimethobenzamide worse.

Dosage Of Trimethobenzamide

Trimethobenzamide comes as a capsule to take by mouth. Trimethobenzamide usually is taken three or four times a day. Take trimethobenzamide at around the same times every day. Follow the directions on your prescription label carefully, and ask your doctor or pharmacist to explain any part you do not understand. Take trimethobenzamide exactly as directed. Do not take more or less of it or take it more often than prescribed by your doctor.


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.


All information has been provided courtesy of MedLinePlus from the National Library of Medicine and from the FDA.