Trimethobenzamide Side Effects

Some side effects of trimethobenzamide may not be reported. Always consult your doctor or healthcare specialist for medical advice. You may also report side effects to the FDA.

For the Consumer

Applies to trimethobenzamide: intramuscular solution, oral capsule

Along with its needed effects, trimethobenzamide may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.

Check with your doctor immediately if any of the following side effects occur while taking trimethobenzamide:

  • Body spasm, with head and heels bent backward and body bowed forward
  • convulsions (seizures)
  • depression
  • shakiness or tremors
  • skin rash
  • sore throat or fever
  • unusual tiredness
  • vomiting (severe or continuing)
  • yellow eyes or skin

Some side effects of trimethobenzamide may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. Also, your health care professional may be able to tell you about ways to prevent or reduce some of these side effects. Check with your health care professional if any of the following side effects continue or are bothersome or if you have any questions about them:

More common
  • Drowsiness
Less common
  • Blurred vision
  • diarrhea
  • dizziness
  • headache
  • muscle cramps

For Healthcare Professionals

Applies to trimethobenzamide: compounding powder, intramuscular solution, oral capsule, rectal suppository

Nervous system

Nervous system adverse effects have included dizziness, drowsiness, headache, disorientation, coma, convulsions, depression of mood, opisthotonus, Parkinson's-like symptoms, trismus, and extrapyramidal symptoms.

Extrapyramidal reactions to trimethobenzamide have been reported in some patients, the youngest of whom was 2 weeks old. This patient received approximately 300 mg rectally, although the drug is not recommended for newborn infants.


Hypersensitivity reactions have included allergic-type skin reactions.


Cardiovascular side effects have been reported rarely. Hypotension has been occasionally associated with intramuscular administration in surgical patients.


Psychiatric side effects have included depression.


Gastrointestinal adverse effects include diarrhea.


An isolated case report described a 50-year-old white female receiving trimethobenzamide capsules during a study protocol for use as a prophylactic antiemetic. After two days of administration, the patient had become jaundiced and her urine was dark. She felt tired, anorexic and nauseated with mild epigastric pain. A liver scan four days after the episode indicated hepatocellular dysfunction. She denied any other factors which may have contributed to the episode.

Hepatic side effects have included reports of jaundice and hepatotoxicity.


Muscle cramps have occurred in some patients.


Hematologic side effects have rarely included blood dyscrasias.


Ocular side effects have included reports of blurring of vision.


Dermatologic side effects reported following intramuscular injection have included pain, stinging, burning, redness and swelling at the site of injection.

The manufacturer recommends giving trimethobenzamide by deep injection into the upper outer quadrant of the gluteal region, and avoiding the escape of the injectable solution along the route, in order to reduce the incidence of side effects at the injection site.

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