Diphenhydramine is an antihistamine active ingredient that has a number of different uses in over-the-counter (OTC) medicines, including topical and oral products. Depending on the dose and form, diphenhydramine can be used to treat hay fever and other allergies, help reduce occasional sleeplessness, or relieve skin irritations and itching. When taken orally, diphenhydramine can be the only active ingredient in allergy medicines, or it can be combined with other ingredients in multi-symptom cough and cold products. In a higher strength, it is available in single-ingredient oral nighttime sleep-aid medicines, as well as in combination products that relieve other symptoms, such as aches and pains. When used externally, diphenhydramine may be combined with other active ingredients in topical pain medicines (i.e. those applied to the body's surface). Topical products containing diphenhydramine should only be applied to small areas of the body. In order to avoid taking too much diphenhydramine, do not use an oral diphenhydramine-containing medicine at the same time as a topic product that also contains diphenhydramine. Avoid getting these products into your eyes.

Symptoms Treated

Symptoms Treated

More specifically: 

Allergies, Occasional sleeplessness, Hay fever, Skin irritations, Itching

Common Products

Other common products:
  • Advil®
  • Bayer®
  • Dimetapp®
  • Ivarest®
  • Sominex®
  • Unisom
  • Store brands (ex. Walmart's "Equate" store brand or CVS Health store brand)

Dosing Information

Different types of products containing this active ingredient have different strengths. That’s why it is always important to read and follow the Drug Facts label. Most medicines warn against use of an active ingredient for longer than 7-10 days. Stop use and ask a doctor if symptoms persist.

Safety Guide

Safety Guide

Diphenhydramine is approved by the U.S. Food and Drug Administration (FDA) and is safe and effective when used according to the Drug Facts label.

Ask a healthcare provider before use if:

  • You have a breathing problem such as emphysema or chronic bronchitis.
  • You have trouble urinating due to an enlarged prostate gland.
  • You have glaucoma.
  • You are taking sedatives or tranquilizers.
  • You are pregnant or breastfeeding.
  • You plan to use to treat chicken pox or measles.
  • Talk to a healthcare provider before using a topical product containing diphenhydramine on a child under the age of 2.
  • Talk to a healthcare provider before giving an OTC allergy medicine with diphenhydramine or a cough and cold product containing diphenhydramine to a child under the age of 6.

Do not use if:

  • You are currently taking a prescription monoamine oxidase inhibitor (MAOI) or if you stopped taking an MAOI less than two weeks ago.
  • You are taking a prescription drug for depression, a psychiatric or emotional condition, or Parkinson's disease.
  • Do not use topical diphenhydramine if you have just taken an oral medicine containing diphenhydramine.
  • Do not use oral diphenhydramine if you have just applied a topical medicine containing diphenhydramine.
  • Do not give a nighttime sleep aid to a child under the age of 12.
  • Never use diphenhydramine or any medicine to sedate or make a child sleepy.

Stop use and ask a doctor if:

  • Your condition worsens or does not improve within seven days.
  • You take too much. Immediately contact a healthcare provider or the poison control national helpline at 800.222.1222.
  • Topical medicines are for external use only. If swallowed, immediately contact a healthcare provider or the poison control national helpline at 800.222.1222.

What are the side effects of diphenhydramine?

  • When using oral diphenhydramine-containing medicines, significant drowsiness may occur. You should avoid alcoholic drinks and use care when driving a motor vehicle or operating machinery.
  • Excitability may occur, especially in children.