The lethal dose of diphenhydramine, the generic name of Benadryl, varies significantly from person to person because of differences in weight and metabolism. There have been cases of people experiencing overdose symptoms... More »

According to PetMD, Benadryl dosages can vary and a veterinarian should be consulted for the proper amount. Although Benadryl is available over-the-counter, do not give a dog any before taking it to the vet. Benadryl is ... More » Pets & Animals Pets Veterinary Health

The recommended dosage of Benadryl for dogs is 1 milligram for every 1 pound of the dog's weight, according to VetInfo. This can be administered every 8 hours on the advice of a veterinarian. More »

Benadryl is the brand name for diphenhydramine, an antihistamine used to alleviate symptoms of sneezing, runny nose, cough and watery eyes that accompany the common cold, allergies and hay fever. It is combined with pain... More »

The pediatric dosage of Benadryl, or diphenhydramine, depends on the child's weight and the formula used, according to the St. Louis Children’s Hospital. For example, the recommended dose of liquid 12.5-milligram suspens... More » Health Medications & Vitamins

A single dose of Diphenhydramine hydrochloride, commonly known as Benadryl, is active in the body for between four and six hours on average. The drug is almost completely excreted from the body within 24 hours, as explai... More »

An oral dose of Benadryl reaches peak blood concentrations 2 to 3 hours after consumption, and the effects usually last for 4 to 6 hours, reports the National Highway Traffic Safety Administration. WebMD suggests taking ... More »