How ZzzQuil Sleep Aid Cures Insomnia


ZzzQuil, an over-the-counter sleeping pill that contains the generic drug diphenhydramine , is used to treat people who have trouble falling asleep or falling asleep. How well does ZzzQuil help with insomnia? What are some common and serious potential side effects of using ZzzQuil? Learn about ZzzQuil, what it does for you, and how it can help you sleep better.

Get Medical Information / Cindy Chang


ZzzQuil is sold without a prescription, which means you don't need a prescription to buy it. ZzzQuil, which is sold in liquid or liquid-filled capsule form, is a sleeping pill used to treat insomnia characterized by difficulty falling asleep or falling asleep.

The active ingredient in ZzzQuil, diphenhydramine, is most often used to relieve allergies; drowsiness is a side effect of this component. But since diphenhydramine is the only active ingredient in the drug, it is touted as safer than other PM sleeping pills, which may also contain Tylenol (acetaminophen), ibuprofen, or other ingredients. It should be taken when you can get eight hours of sleep to avoid morning side effects.

How does it work

Since the main ingredient in ZzzQuil is diphenhydramine, it belongs to a group of drugs called antihistamines . Antihistamines block the action of the chemical histamine, a signal from the central nervous system that promotes wakefulness. As a result, taking antihistamines can cause drowsiness. Diphenhydramine and histamine work in the brain and other parts of the body and cause possible side effects. Diphenhydramine can also suppress coughing or nausea and can cause uncontrolled movements called dyskinesias.

Studies have shown that diphenhydramine, the main ingredient in ZzzQuil, is only moderately effective in improving sleep. Research shows that people fall asleep on average about 8 minutes faster compared to a placebo. General sleep improves in an average of about 12 minutes .

The American Academy of Sleep Medicine does not recommend using this drug as a sleeping pill because the benefits roughly equal the potential harm .

Who can use it

Talk to your doctor if you are concerned about how ZzzQuil might affect your health or interact with other medications. In general, it should not be used in children under 12 years of age and should be used with caution in the elderly .

Some of the conditions that may warrant additional care when considering using ZzzQuil include:

  • Glaucoma
  • Hyperthyroidism
  • Heart disease
  • High blood pressure
  • Asthma
  • Chronic Obstructive Pulmonary Disease (COPD)
  • Pneumonia
  • Peptic ulcer
  • Enlarged prostate
  • Bowel or bladder obstruction

If you have any of these conditions, you should speak to your doctor before using ZzzQuil. Since this medication may interact with other medications, especially those that affect the brain, check with your doctor or pharmacist before use. You can use the Provider Discussion Guide below to start this conversation.

A Discussion Guide for a Healthcare Provider for Insomnia

Get our printed guide to your next doctor's appointment to help you ask the right questions.

Side effects

The effect of the morning "hangover" can occur with the use of the drug, especially if after taking the drug there is not enough time in bed; in higher doses; with the use of other drugs; or if you have certain medical conditions, including untreated sleep disorders such as sleep apnea . Some of the side effects that can commonly occur when using ZzzQuil include :

  • Confusion of conscience (delirium)
  • Clumsiness
  • Drowsiness
  • Dizziness
  • Increased pressure in the eye
  • Headache
  • Stomach ache
  • Dry mouth or nose
  • Hyperactivity
  • Constipation
  • Thick discharge from the lungs
  • Difficulty urinating
  • Low blood pressure
  • Blurred or double vision
  • Fast or irregular heartbeat
  • Photosensitivity
  • Perspiration
  • erectile dysfunction

Possible serious reactions.

As with any medicine, there is also a risk of serious side effects with ZzzQuil. They are less common than the common side effects mentioned above. When using ZzzQuil, these can include :

  • Anaphylaxis (severe allergic reaction including difficulty breathing)
  • Low blood cell count (including anemia)
  • Abnormal heart rate
  • Seizures
  • Toxic psychosis (characterized by confusion and abnormal behavior)
  • Acute labyrinthitis (inner ear problems)

Safety measures

As noted above, some people are advised to use ZzzQuil with caution or not to use ZzzQuil. Since this is an over-the-counter drug, it may seem that the overall risks may be slightly less compared to other prescription drugs used to treat insomnia. However, this may not be the case and you should discuss additional options with your healthcare provider.

Taking more than the prescribed dose or drinking it with alcohol can lead to an overdose and serious health consequences. If you have any difficulty using ZzzQuil, you should closely communicate with your primary healthcare provider.

It is possible, but unlikely, for pregnant women to harm a developing fetus. Also , ZzzQuil is likely to be safe while breastfeeding, although caution should be exercised .

Given the limited effectiveness of this drug, other treatment options for insomnia may be appropriate.

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