Didryl syrup is indicated in the treatment of perennial and seasonal (hay fever) allergic rhinitis and conjunctivitis due to inhalant allergens and food, urticaria, angioedema and pruritic skin disorders. It is also used in the prevention and treatment of motion sickness. and symptomatic relief of cough and common colds .

Adults: 25 mg (2.5 teaspoonfuls) 3 times daily with 50 mg (5 teaspoonfuls) at bedtime. Children (6 to 12 years): 10 to 20 mg (1 to 2 teaspoonfuls) 2 to 3 times daily. Below 6 years not recommended. Use in pregnancy & lactation: There are no adequate and well-controlled studies in pregnant women using Diphenhydramine hydrochloride. Therefore, Diphenhydramine hydrochloride should be used in pregnancy only if clearly needed. Diphenhydramine hydrochloride has been reported to be excreted in breast milk so the use of Diphenhydramine hydrochloride in lactating mother is not recommended.