The most common adverse effects are diarrhoea, muscle cramps, fatigue, nausea, vomiting and insomnia.
The frequency of Alzheimer patients from each stage experiencing adverse effects who use donepezil hydrochloride are given as follows.
Adverse reactions reported as more than an isolated case are listed as follows, by system organ class and by frequency. Very common (≥ 1/10), common (≥1/100 to <1/10), uncommon (≥1/1,000 to <1/100), rare (≥1/10,000 to <1/1,000), very rare (<1/10,000), unknown (cannot be expected from the available data).
Infections and infestations: Common: Cold.
Metabolism and nutritional disorders: Common: Anorexia.
Psychiatric disorders: Common: Hallucination**, agitation**, aggressive behaviours**, abnormal dreams.
Nervous system disorders: Common: Syncope*, dizziness, insomnia. Uncommon: Seizure*. Rare: Extrapyramidal symptoms. Very Rare: Neuroleptic Malignant Syndrome.
Cardiac disorders: Uncommon: Bradycardia. Rare: Sino-atrial block, atrioventricular block.
Gastrointestinal disorders: Very common: Diarrhoea, nausea. Common: Vomiting, abdominal discomfort. Uncommon: Gastrointestinal bleeding, gastric and duodenal ulcers.
Hepato-biliary disorders: Rare: Hepatic dysfunction including hepatitis***.
Diseases of skin and subcutaneous tissue: Common: Urticaria, rash.
Musculoskeletal disorders and diseases of connective tissues and bones: Common: Muscle cramps. Very rare: Rhabdomyolysis.
Hepato-biliary disorders: Common: Urinary incontinence.
General disorders and administration-site diseases: Very common: Headache. Common: Pain, weakness.
Investigations: Uncommon: Minor increase in serum concentration of muscle creatine kinase.
Injury and poisoning: Common: Accident.
* In investigating patients for syncope or seizure the possibility of heart block or long sinusal pauses should be considered.
** Reports of hallucinations, abnormal dreams, nightmares, agitation and aggressive behaviour have resolved on dose-reduction or discontinuation of treatment.
*** In cases of unexplained liver dysfunction, withdrawal of Donepezil should be considered.