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Diphenhydramine

Diphenhydramine is an antihistamine active ingredient that has a number of different uses in over-the-counter (OTC) medicines. Depending on the dose and form, the active ingredient diphenhydramine can be used to treat hay fever and other allergies, to help reduce occasional sleeplessness, or to relieve skin irritations and itching. It may be written as diphenhydramine, diphenhydramine hydrochloride (HCl), or diphenhydramine citrate, but each has the same effect in the human body.

When taken orally, diphenhydramine can be the only active ingredient in allergy medicines, or it can be combined with other ingredients in multiple-symptom cough and cold products. In a higher strength, diphenhydramine 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 pain medications applied on the body surface (or topical).

Diphenhydramine is approved by the U.S. Food and Drug Administration (FDA) and is safe and effective when used according to label directions. Taking too much of any medicine could potentially cause a problem. In order to avoid taking too much diphenhydramine, do not use an oral diphenhydramine-containing medicine at the same time as a topical product that also contains diphenhydramine.

*Diphenhydramine may not be contained in all products sold under these brands. Please read the OTC Drug Facts label carefully for active ingredient information for specific products.

Tips for Medicines with Diphenhydramine

When using oral diphenhydramine-containing medicines, it is important to know that:

  • Significant drowsiness may occur.
  • You should avoid alcoholic drinks.
  • You should use care when driving a motor vehicle or operating machinery.

Do not use oral diphenhydramine if:

  • You have just applied a topical medicine containing diphenhydramine.

Ask a healthcare professional before use if:

  • You are pregnant or breastfeeding.
  • You have emphysema, chronic bronchitis, glaucoma, or trouble urinating due to an enlarged prostate gland.
  • You are taking sedatives or tranquilizers.

Stop use and ask a doctor if:

  • You take too much. Immediately contact a doctor or the poison control national helpline at 800.222.1222.

When using topical diphenhydramine-containing medicines, it is important to know that:

  • Topical medicines are for external use only. If swallowed, immediately contact a doctor or the poison control national helpline at 800.222.1222.
  • The products should only be applied to small areas of the body.
  • You should avoid getting them into your eyes.

Do not use topical diphenhydramine if:

  • You have just taken an oral medicine containing diphenhydramine.

Ask a healthcare professional before use if:

  • You plan to use to treat chicken pox or measles.

Stop use and ask a doctor if:

  • Your condition worsens or does not improve within seven days.

If you have questions about any of the medicines you are taking or if you have any unexpected side effects, talk to a healthcare professional. And of course, keep all medicines out of the reach and sight of children.

Tips for Parents

When using oral diphenhydramine-containing medicines:

  • Do not give an OTC allergy medicine with diphenhydramine or a cough and cold product containing diphenhydramine to a child under the age of six unless a doctor tells you to.
  • Excitability may occur, especially in children.
  • Never use diphenhydramine or any medicine to sedate or make a child sleepy.
  • Do not give a nighttime sleep aid to a child under the age of 12.

When using topical diphenhydramine-containing medicines:

  • Talk to a healthcare professional before using a topical product containing diphenhydramine on a child under the age of two.

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