The more common adverse reactions involve anticholinergic effects such as dry mouth, disturbances of visual accommodation, constipation and urinary retention. Also commonly seen are light-headedness, drowsiness, decreased perspiration and mild tremors, as well as insomnia. Adverse reactions of the cardiovascular system may be much more serious; however, these occur less frequently.

Note: Some of the following adverse reactions have been reported with other TCAs and not specifically with amitriptyline. Pharmacologic similarities among the TCA drugs require that each reaction be considered when amitriptyline is administered

Frequently: dry mouth and rarely associated sublingual adenitis, blurred vision, disturbances of accommodation, constipation, perspiration, flushing. Occasionally: delayed micturition, dilation of the urinary tract. In isolated cases: mydriasis, glaucoma, paralytic ileus, urinary frequency.

Occasionally: confusional states (especially in the elderly) with hallucinations, disorientation, delusions, anxiety, agitation, insomnia, restlessness, nightmares, hypomania, mania, exacerbation of psychosis, decrease in memory, feeling of unreality. In isolated cases: feeling of weakness, aggressiveness.

Frequently: hypotension, particularly orthostatic hypotension with associated vertigo, tachycardia, ECG changes (including flattening or inversion of T waves). Occasionally: arrhythmia, disturbances in cardiac conduction, palpitation, syncope. In isolated cases: hypertension, congestive heart failure, myocardial infarction, heart block, asystole, stroke, peripheral vasospastic reactions.

Frequently: drowsiness, fatigue, tremors. Occasionally: insomnia, dizziness, headache, paresthesia (numbness, tingling sensation, symptoms suggestive of peripheral neuropathy). Rarely: seizures. In isolated cases: tinnitus, incoordination, ataxia, alterations in EEG patterns, extrapyramidal symptoms, myoclonus, speech disorders.

Frequently: weight gain. Occasionally: increased or decreased libido, impotence. In isolated cases: gynecomastia in the male, breast enlargement and galactorrhea in the female, testicular swelling, elevation or depression of blood sugar levels, weight loss, syndrome of inappropriate antidiuretic hormone secretion (SIADH).

In isolated cases: agranulocytosis, eosinophilia, leukopenia, purpura and thrombocytopenia may occur as an idiosyncratic response.

Occasionally: skin rash, urticaria. In isolated cases: petechiae, itching, photosensitization (avoid excessive exposure to sunlight), edema (general or of face and tongue), drug fever, obstructive jaundice, nasal congestion, alopecia, allergic alveolitis (pneumonia) with or without eosinophilia.

Occasionally: nausea, vomiting, anorexia. Rarely: elevated transaminases. In isolated cases: diarrhea, bitter taste, stomatitis, epigastric distress, abdominal cramps, black tongue, dysphagia, increased salivation, hepatitis with or without jaundice.

If prolonged treatment is abruptly terminated, withdrawal symptoms may occur. These may include sleep disturbances, gastrointestinal discomfort, flu-like symptoms, anxiety, depression, hypomania, mania, panic and depersonalization, delirium, dizziness, tremor, muscle twitching and, rarely, dyskinesia. These usually occur within 1 to 3 days of discontinuation, are mild and self-limiting and resolve within 2 weeks. Very rarely, cardiac disturbances may also occur.