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Benzocaine / trimethobenzamide Side Effects

Not all side effects for benzocaine / trimethobenzamide may be reported. You should always consult a doctor or healthcare professional for medical advice. Side effects can be reported to the FDA here.

For the Consumer

Applies to benzocaine / trimethobenzamide: rectal suppository

Get emergency medical help if you have any of these signs of an allergic reaction:hives; difficulty breathing; swelling of your face, lips, tongue, or throat.

If you experience any of the following serious side effects, stop taking benzocaine and trimethobenzamide and seek emergency medical attention or contact your doctor immediately:

Stop using this medication and call your doctor at once if you have any of these serious side effects:

  • jaundice (yellowing of the skin or eyes);

  • seizure (convulsions); or

  • easy bruising or bleeding, unusual weakness;

  • tremor (uncontrolled shaking); or

  • muscle cramps, severe muscle spasms.

Other less serious side effects are more likely to occur. Continue using benzocaine and trimethobenzamide and talk with your doctor if you have any of these less serious side effects:

  • drowsiness or dizziness;

  • headache;

  • feeling depressed or disoriented; or

  • blurred vision.

Side effects other than those listed here may also occur. Talk to your doctor about any side effect that seems unusual or that is especially bothersome.

For Healthcare Professionals

Applies to benzocaine / trimethobenzamide: rectal suppository


Cardiovascular side effects have included hypotension. It has been occasionally associated with intramuscular administration of trimethobenzamide in surgical patients.[Ref]


Gastrointestinal side effects have included diarrhea.[Ref]


Hematologic side effects have rarely included blood dyscrasias. Methemoglobinemia, characterized by cyanosis, has been reported with the use of benzocaine topical.[Ref]


Hepatic side effects have included hepatotoxicity and jaundice associated with the use of trimethobenzamide.[Ref]

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.[Ref]


Hypersensitivity side effects have included allergic-type skin reactions. Bronchospasm, shock, and anaphylactoid reactions may occur and, in general, have occurred with high plasma levels of the local anesthetic. Parkinson-like symptoms have been reported following the use of trimethobenzamide. These have abated following drug discontinuation, but in some cases treatment may be indicated.[Ref]


Musculoskeletal side effects have included muscle cramps associated with the use of trimethobenzamide.[Ref]

Nervous system

Nervous system side effects have included dizziness, drowsiness, headache, disorientation, convulsions, opisthotonus, Parkinson's-like symptoms, trismus, and extrapyramidal symptoms.[Ref]

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.[Ref]


Psychiatric side effects have included depression.[Ref]


Local side effects have included burning, stinging, tenderness, and sloughing following the use of benzocaine topical. Pain has been reported following the intramuscular administration of trimethobenzamide.[Ref]


Ocular side effects have included blurred vision following the use of trimethobenzamide.[Ref]


1. "Product Information. Tigan (trimethobenzamide)." Monarch Pharmaceuticals Inc, Bristol, TN.

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