Active ingredient found in Benadryl and over the counter sleep aids such as Nytol or Unisom. Can be used recreationally if taken in doses exponentially higher than recommended. When abused, people take up to 30+ the recommended dose. When taken in high doses symptoms include auditory, tactile, and visual hallucinations, tachychardia (increased heart rate), dry mouth, ringing in ears, impaired motor control, increased or difficulty urinating, constipation or diarrhea, rapid respiration, extreme drowsiness, impaired memory, upset stomach, possible anxiety, burning and redness in eyes, impaired concentration, dilated puils and general dreamlike feeling. Not recommended to be used in combination with alcohol or depressants as symptoms are intensified and overdose is a risk. Really not very good for you and the high isn't that fun but you'll probably take it anyway.
She sat in her room all night and ate a pack of Benadryl so she could get high on the diphenhydramine.