Post Marketing Data: Adverse drug reactions (ADRs) identified during post-marketing experience with diphenhydramine are confusional state, irritability, nervousness, hallucination, sedation, agitation, insomnia, coordination abnormal, convulsion, headache, paraesthesia, tremor, vision blurred, tinnitus, palpitations, tachycardia, dry throat, hypotension, chest discomfort, nasal dryness, constipation, diarrhoea, dyspepsia, nausea, vomiting, rash, pruritus, urticaria, urinary retention.