Benadryl is a trade (brand) name for diphenhydramine hydrochloride, which is a sedating antihistamine.

The dosage of diphenhydramine varies depending on the salt being used and the condition being treated.

The following oral dosages for adults are those recommended for Benadryl. Dosages for children vary depending on age or body weight: please consult with a pediatrician.

• Allergic rhinitis: 25mg to 50 mg up to every four to six hours as needed. Maximum: 300 mg/day
• Cold symptoms, itch (pruritus), or urticaria: 25mg to 50 mg up to every four to six hours as needed. Maximum: 300 mg/day
• Insomnia: 50mg once at bedtime. Maximum dose: 50mg
• Motion sickness: 25mg to 50mg up to three or four times a day as needed. Maximum: 300 mg/day

Note that these dosages are for adults who are otherwise healthy and are on no interacting medicines. The dosage of diphenhydramine may need reducing in those with certain medical conditions or taking certain medicines. Diphenhydramine is not suitable for some people.