If condition worsens or persists for more than 7 days, consult a physician. Do not use other drugs containing diphenhydramine while using this product. In infants and children, especially, antihistamines in overdosage may cause hallucinations, convulsions, or death. As in adults, antihistamines may diminish mental alertness in children. In the young child, particularly, they may produce excitation.
Antihistamines are more likely to cause dizziness, sedation and hypotension in elderly patients.
Its use therefore in such patients should involve consideration of expected benefits and possible risks. Avoid s.c. or perivascular injection. Since the depressant effects of antihistamines are additive to those of other drugs affecting the CNS, patients should be cautioned against drinking alcoholic beverages or taking hypnotics, sedatives, psychotherapeutic agents or other drugs with CNS depressant effects during antihistaminic therapy. Diphenhydramine has an atropine like action and therefore should be used with caution in patients with a history of bronchial asthma, increased intraocular pressure, hyperthyroidism, cardiovascular disease or hypertension. Adverse Effects Drowsiness, dizziness, dryness of mouth, nausea and nervousness may occur.