Mecamylamine Side Effects

It is possible that some side effects of mecamylamine may not have been reported. These can be reported to the FDA here. Always consult a healthcare professional for medical advice.

For the Consumer

Applies to mecamylamine: oral tablet

Along with its needed effects, mecamylamine 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 mecamylamine:

More common
  • Dizziness or lightheadedness, especially when getting up suddenly from a lying or sitting position
Less common
  • Difficult urination
  • Bloating and frequent loose stools
  • confusion or excitement
  • constipation (severe)
  • convulsions (seizures)
  • mental depression
  • shortness of breath
  • trembling
  • uncontrolled movements of the face, hands, arms, or legs

Some side effects of mecamylamine 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
  • Constipation
  • drowsiness
  • unusual tiredness
Less common or rare
  • Blurred vision
  • decreased sexual ability or interest in sex
  • dryness of the mouth
  • enlarged pupils
  • loss of appetite
  • nausea and vomiting
  • weakness

For Healthcare Professionals

Applies to mecamylamine: oral tablet


Gastrointestinal side effects have included ileus, constipation (sometimes preceded by small, frequent liquid stools), nausea, vomiting, anorexia, glossitis, and dryness of mouth.


Cardiovascular side effects have included orthostatic dizziness and syncope and postural hypotension.

Nervous system

Nervous system side effects have included convulsions, choreiform movements, tremor, and paresthesias.

These side effects have occurred most often when large doses of mecamylamine were used, especially in patients with cerebral or renal insufficiency.


These side effects have occurred most often when large doses of mecamylamine were used, especially in patients with cerebral or renal insufficiency.

Psychiatric side effects have included mental aberrations.


Respiratory side effects have included interstitial pulmonary edema and fibrosis.


Genitourinary side effects have included urinary retention and impotence.


Ocular side effects have included blurred vision and dilated pupils.


General side effects have included decreased libido, weakness, fatigue, and sedation.

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