Most adults take 25–50 mg of diphenhydramine every 4–6 hours as needed and stay at or under 300 mg in 24 hours unless a clinician directs otherwise.

Most puppies shouldn’t get diphenhydramine unless a veterinarian has told you to; when it’s approved, dosing is based on weight, not age.

Most dogs get diphenhydramine at about 1 mg per pound of body weight per dose, yet the right amount depends on weight, product type, and your dog’s health.

Many vets dose diphenhydramine by weight, often 2–3 mg/kg by mouth about every 12 hours, when it fits the cause of the itch.

Many vets start diphenhydramine near 1 mg per pound every 8–12 hours, yet the safest dose depends on your dog and the product you’re using.

Many vets use diphenhydramine at about 1 mg per pound for dogs, but the right amount depends on your dog and the product label.

For mild allergy symptoms, many adults use diphenhydramine 25–50 mg every 4–6 hours, up to 300 mg in 24 hours.

Adult OTC labels cap diphenhydramine at 300 mg per 24 hours, taken in divided doses every 4–6 hours.

Most pregnant adults can follow label dosing: 25–50 mg every 4–6 hours, with no more than 6 doses in 24 hours unless a clinician says otherwise.

Most adults can take diphenhydramine 25–50 mg every 4–6 hours, up to 300 mg in 24 hours, unless a prescriber told you differently.