Skip to main content

How much Benadryl can I take? What is too much?

Medically reviewed by Carmen Pope, BPharm. Last updated on Feb 13, 2024.

At one time. Also known as diphenhydramine.

Official answer

by Drugs.com

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.

Read next

The Hat Man is a fictional figure that started appearing on certain internet sites in the early 2000s that has recently been referred to as the “Benadryl Hat Man” after reports of people hallucinating and sighting him after overconsumption or abuse of Benadryl. Most of these reports have appeared on Reddit or the image-based bulletin site 4chan. Continue reading

Benadryl is quickly absorbed after oral administration and it starts to work within 30 minutes with peak effects reached within one to two hours. The effects of Benadryl last from four to six hours. Benadryl in the injectable form has a rapid onset of action. You will know when Benadryl starts to work because your allergy symptoms, such as congestion, runny nose, itchy eyes, or a skin rash, will start to feel better. Continue reading

One of the most common side effects with Benadryl is drowsiness, but in some people it can have the opposite effect, known as paradoxical excitation. Instead of feeling sleepy,
you may experience excitation, agitation or insomnia (trouble sleeping), which might make your anxiety symptoms feel worse. This may be more common in young children. Continue reading

Related medical questions

Drug information

Related support groups

Medical Disclaimer