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Tacrine Side Effects

Medically reviewed by Last updated on Dec 28, 2023.

Applies to tacrine: oral capsule.


Before taking tacrine, tell your doctor if you have heart disease or a heart rhythm disorder such as "sick sinus syndrome" (slow heartbeats), an enlarged prostate, urination problems, asthma, obstructive pulmonary disease, or a seizure disorder such as epilepsy.

Tacrine is most effective when taken between meals on an empty stomach, but you may take it with food if it upsets your stomach.

It is important to use tacrine regularly to get the most benefit. Get your prescription refilled before you run out of medicine completely.

Your doctor may occasionally change your dose to make sure you get the best results from this medication.

Do not change your tacrine dose without your doctor's advice. Taking this medication improperly can lead to serious behavioral side effects or a worsening of Alzheimer's symptoms.

Call your doctor at once if you have serious side effects such as confusion, hallucinations, extreme or sudden changes in behavior, seizure (convulsions), pain or burning when you urinate, dark urine, clay-colored stools, or jaundice (yellowing of the skin or eyes).

Do not stop taking this medication without first talking to your doctor. If you stop taking tacrine suddenly, your condition may become worse.

Tacrine can cause side effects that may impair your thinking or reactions. Be careful if you drive or do anything that requires you to be awake and alert.

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

Call your doctor at once if you have any of these serious side effects:

Less serious side effects of tacrine include:

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 tacrine: oral capsule.


Elevations in LFTs (liver function tests) have been reported in as many as 50% of patients started on tacrine therapy. LFTs should be closely monitored while patients are treated with tacrine, particularly when therapy is initiated and when dosages are altered.

Specific recommendations for LFT monitoring are as follows:

Every-other-week monitoring of LFTs, particularly ALT, is recommended during the first sixteen weeks of tacrine therapy.

If modest elevations of up to two times the ULN (upper limit of normal) occur, continued every-other-week LFTs are recommended.

If elevations of up to three times ULN occur, weekly LFT monitoring is recommended until LFTs return to normal.

If elevations of up to five times ULN occur, a daily dosage reduction of 40 mg and weekly LFT monitoring is recommended until LFTs return to normal.

If elevations greater than five times ULN occur, discontinuation of tacrine therapy is recommended until LFTs return to normal.

Rechallenge may be attempted in patients who have discontinued tacrine therapy as a result of elevated LFTs (but rechallenge is contraindicated in patients with a history tacrine-induced jaundice). Rechallenge should only proceed once LFTs have returned to normal. A daily dose of 40 mg may be attempted. LFTs should be monitored weekly during rechallenge. Limited experience is available concerning rechallenge in patients with a history of tacrine-induced LFT elevations greater than 10 times ULN.[Ref]

Twenty-five percent of patients may experience a rise in ALT to three times normal. Seven percent may experience a rise in ALT to 10 times normal. Large rises in LFTs have been associated with hepatocellular injury rarely. Pathologic findings associated with tacrine-induced hepatotoxicity include granulomatous changes and hepatocellular necrosis.[Ref]


Cholinergic adverse effects occur in as many as 68% of treated patients and include nausea, vomiting, diarrhea, dyspepsia, anorexia, restlessness, tremors, myalgia, arthralgia, excessive sweating, rash and frequent micturition. Hypotension, hypertension, bradycardia, syncope, ataxia and confusion have also been reported less frequently.[Ref]

The cholinomimetic effects of tacrine may result in an increase in gastric acid secretion and may therefore increase the risk of gastric ulceration in some patients.

Because of the potential vagotonic effects of cholinomimetic therapy, use in patients with "sick sinus syndrome" should be undertaken, if at all, with caution.[Ref]


Agranulocytosis has been reported in four of 8000 treated patients. Three of the four patients had medical conditions associated with agranulocytosis.[Ref]

Nervous system

A case of exacerbation of parkinsonism has been reported. Some clinicians have also reported vertigo and paresthesias as nervous system effects. Six cases of generalized tonic or tonic-clonic seizures have also been reported.[Ref]


1. Ford JM, Truman CA, Wilcock GK, Roberts CJ (1993) "Serum concentrations of tacrine hydrochloride predict its adverse effects in Alzheimer's disease." Clin Pharmacol Ther, 53, p. 691-5

2. Summers WK, Koehler AL, Marsh GM, Tachiki K, Kling A (1989) "Long-term hepatotoxicity of tacrine." Lancet, 1, p. 729

3. Ames DJ, Bhathal PS, Davies BM, Fraser JR (1988) "Hepatotoxicity of tetrahydroaminoacridine." Lancet, 1, p. 887

4. Ames DJ, Bhathal PS, Davies BM, Fraser JR, Gibson PR, Roberts S (1990) "Heterogeneity of adverse hepatic reactions to tetrahydroaminoacridine." Aust N Z J Med, 20, p. 193-5

5. Hammel P, Larrey D, Bernuau J, Kalafat M, Freneaux E, Babany G, Degott C, Feldmann G, Pessayre D, Benhamou JP (1990) "Acute hepatitis after tetrahydroaminoacridine administration for Alzheimer's disease." J Clin Gastroenterol, 12, p. 329-31

6. Knapp MJ, Knopman DS, Solomon PR, et al. (1994) "A 30-week randomized controlled trial of high-dose tacrine in patients with alzheimers disease." JAMA, 271, p. 985-91

7. Watkins PB, Zimmerman HJ, Knapp MJ, Gracon SI, Lewis KW (1994) "Hepatotoxic effects of tacrine administration in patients with alzheimers disease." JAMA, 271, p. 992-8

8. Wilcock GK, Surmon D, Forsyth D, Morgan R (1988) "Cholinergic side-effects of tetrahydroaminoacridine." Lancet, 2, p. 1305

9. Forsyth DR, Surmon DJ, Morgan RA, Wilcock GK (1989) "Clinical experience with and side-effects of tacrine hydrochloride in Alzheimer's disease: a pilot study." Age Ageing, 18, p. 223-9

10. (2001) "Product Information. Cognex (tacrine)." Parke-Davis

11. Ott BR, Lannon MC (1992) "Exacerbation of parkinsonism by tacrine." Clin Neuropharmacol, 15, p. 322-5

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

Some side effects may not be reported. You may report them to the FDA.