Using Diphenhydramine or Benadryl as a Sleep Aid Insomnia Medication

Information About This Over-The-Counter Sleeping Pill

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The over-the-counter medication diphenhydramine is found in many sleeping pills intended for insomnia treatment. It is the sleep-inducing element in many medications used as sleep aids.

Its use does not require a prescription, so it is sometimes used as the initial option for the treatment of acute insomnia to help initiate and maintain sleep. Due to the potential for side effects, especially among older people, alternatives may be sought if chronic insomnia persists.

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Diphenhydramine has many potential uses. As it does cause sleepiness, it is only recommended for short-term treatment of insomnia or acute insomnia. By definition, this is insomnia that occurs for less than three months.

It is one of the ingredients found in multiple sleep aids:

  • Tylenol PM
  • Advil PM
  • Aleve PM
  • ZzzQuil
  • Benadryl

It may help you get to sleep or stay asleep. However, there is little evidence that diphenhydramine actually improves insomnia, and it may cause sleepiness the day after taking it.

Healthcare provider do not recommend the routine or chronic use of diphenhydramine to treat insomnia.

In addition to its use as a sleep aid, diphenhydramine is often administered to relieve allergies or treat allergic reactions, and it can be helpful in preventing motion sickness. It is also used to alleviate extrapyramidal symptoms, which may occur as a side effect of other medications.

How It Works

Diphenhydramine is part of a class of medications called antihistamines. It works at the level of neurotransmitters, which are the chemical messengers within the brain.

It allows the neurotransmitter called histamine to build up in the spaces called synapses that are present between nerve cells. This leads to sedative effects and is accomplished by blocking its uptake into nearby cells.

Diphenhydramine works both centrally within the brain as well as in peripheral nerve cells in other parts of the body. It possesses other effects and can suppress a cough, nausea, and uncontrolled movements called dyskinesis.

Precautions and Contraindications

Children less than 2 years old should not use diphenhydramine. Additionally, caution should be used when this medication is used by children younger than 6 years old and by the elderly.

If you have increased intraocular pressure, such as in glaucoma, you should use diphenhydramine cautiously. Other conditions may also require caution, including individuals who have:

  • Asthma
  • Bowel or bladder obstruction
  • Chronic obstructive pulmonary disease
  • Heart disease
  • High blood pressure
  • Hyperthyroidism
  • Peptic ulcer disease
  • Pneumonia
  • Prostate enlargement

If you have these conditions, you may wish to discuss your risk with your healthcare provider before starting to use the medication.

Side Effects

Some side effects that may commonly occur with diphenhydramine include:

  • Delirium (confusion)
  • Diminished coordination or cognitive function
  • Drowsiness
  • Dizziness
  • Increased intraocular pressure (similar to glaucoma)
  • Headache
  • Stomach discomfort
  • Thick lung secretions
  • Dry mouth or nose
  • Hyperactivity
  • Constipation
  • Difficulty urinating
  • Low blood pressure
  • Blurry or double vision
  • Rapid or irregular heart rate
  • Sensitivity to light
  • Sweating
  • Erectile dysfunction (impotence)


With the use of any drug, there are also risks of serious side effects. These occur more rarely. When using diphenhydramine, these may include:

  • Anaphylaxis (severe allergic reaction including difficulty breathing)
  • Low blood cell counts (agranulocytosis, anemia, thrombocytopenia, and leukopenia)
  • Abnormal heart rhythms
  • Seizures
  • Toxic psychosis
  • Acute labyrinthitis (inner ear problems)

Warnings and Interactions

As noted above, certain people should use diphenhydramine with caution, or not at all. It is an over-the-counter medication, so the risks are thought to be slightly lower compared to other prescription medications.

Harm to a developing fetus during pregnancy is possible but unlikely, and diphenhydramine is probably safe in lactation and breastfeeding, though caution is advised.

Diphenhydramine has the potential to interact with some other drugs, especially those that affect the brain, so you may wish to review your medications with your healthcare provider or pharmacist before using it.

A Word From Verywell

If you experience any difficulties, you should be in close contact with your primary health provider. If you suffer from chronic insomnia that occurs at least three nights per week and lasts at least two weeks, consider the use of cognitive behavioral therapy for insomnia (CBTI) to resolve the condition instead.

You can use our Doctor Discussion Guide below to start a conversation with your healthcare provider about the most appropriate treatment approach.

Insomnia Doctor Discussion Guide

Get our printable guide for your next healthcare provider's appointment to help you ask the right questions.

Doctor Discussion Guide Woman
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7 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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  3. Sateia MJ, Buysse DJ, Krystal AD, Neubauer DN, Heald JL. Clinical practice guideline for the pharmacologic treatment of chronic insomnia in adults: An American Academy of Sleep Medicine clinical practice guidelineJ Clin Sleep Med. 2017;13(2):307–349. doi:10.5664/jcsm.6470

  4. Food and Drug Administration. Diphenhydramine hydrochloride injection, USP label.

  5. Farzam K, O'Rourke MC. Antihistamines. In: StatPearls.

  6. NIH Toxicology Data Network. Diphenhydramine.

  7. Brzezińska-wcisło L, Zbiciak-nylec M, Wcisło-dziadecka D, Salwowska N. Pregnancy: a therapeutic dilemma. Postepy Dermatol Alergol. 2017;34(5):433-438. doi:10.5114/ada.2017.71108

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