Geriatric patients may be more disposed to developing adverse CNS depressant effects, and alcohol intake will increase sedation. If symptoms persist or are severe, a dose reduction or change to another antihistamine may be advisable. Other possible CNS effects include headache and hallucinations. Antihistamines sometimes cause CNS stimulation. This effect is more likely to occur in children with overdoses, and symptoms may include restlessness or akathisia, insomnia, palpitations, and seizures.
Cyproheptadine exerts a small degree of anticholinergic activity.
Geriatric patients are more likely to experience such adverse reactions. Some of these adverse reactions may be relieved by taking the drug with meals or milk. Adverse cardiovascular responses are likely to be associated with the anticholinergic properties or the quinidine-like anesthetic effects of antihistamines. Alpha-adrenergic blockade may lead to hypotension. Hypertension may also occur.