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OTC sleep aids

By the Life in Good Form editors. Updated 2026-10-15.

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Quick answerMost over-the-counter sleep aids contain one of two antihistamines: diphenhydramine (as in ZzzQuil Nighttime Sleep-Aid liquid, 50 mg per 30 mL dose) or doxylamine succinate (as in Unisom SleepTabs and ZzzQuil Ultra, 25 mg per tablet). The labels say they are for occasional sleeplessness, are not for children under 12, should be taken only at bedtime, and should not be combined with alcohol or other products containing the same ingredient. Stop and ask a doctor if sleeplessness continues for more than two weeks, because insomnia may be a symptom of a serious underlying illness.
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Diphenhydramine vs doxylamine

ProductActive ingredientLabel directions (12 and over)
ZzzQuil Free and Clear liquidDiphenhydramine HCl 50 mg per 30 mL30 mL at bedtime if needed; only one dose per 24 hours
Unisom SleepTabsDoxylamine succinate 25 mg per tablet1 tablet 30 minutes before bed; once daily
ZzzQuil UltraDoxylamine succinate 25 mg per tablet1 tablet 30 minutes before bed; once daily

Details are from each product's DailyMed label. All three say do not use in children under 12.

What OTC sleep aids are for

The ZzzQuil liquid label lists its use as relief of occasional sleeplessness and says it reduces time to fall asleep if you have difficulty falling asleep. The doxylamine labels say they help to reduce difficulty in falling asleep. None is meant for nightly long-term use: all three say stop and ask a doctor if sleeplessness persists continuously for more than two weeks.

Habits often matter more than pills. See our blackout curtains guide and sleep tracker guide for ways to look at your sleep environment and patterns.

Who should not use them

Avoid doubling up

The ZzzQuil liquid label says do not use it with any other product containing diphenhydramine, even one used on skin. The Unisom label says do not use it with any other product containing doxylamine. Many nighttime cold, allergy and pain products contain one of these antihistamines, so read the active ingredients on everything you take at night.

For allergy medicines that are less likely to cause drowsiness, see our allergy relief tablets guide.

Using a sleep aid safely

Ingredients, sodium and storage

Inactive ingredients differ between products. Each 30 mL dose of ZzzQuil Free and Clear liquid contains sodium 88 mg and is sweetened with sorbitol, saccharin sodium and sucralose; the label says store it at no greater than 25 C. Unisom SleepTabs and ZzzQuil Ultra list FD&C blue no. 1 aluminum lake as a color and say to store at 20 to 25 C (68 to 77 F). Unisom also says to keep the carton because it contains important information. If you follow a low-sodium diet, avoid certain dyes or have sensitivities to sweeteners, compare these lists before you buy, and keep every sleep aid out of reach of children.

When to see a doctor

If sleeplessness lasts more than two weeks, the labels say to stop and ask a doctor, since insomnia may be a symptom of a serious underlying medical illness. Also talk to a doctor about loud snoring, gasping during sleep, or daytime sleepiness, which can point to other sleep problems. For a supplement some people try, see our sleep gummies guide, and check with a pharmacist before combining anything with a sleep aid.

What to look for when you buy

Unisom SleepTabs (doxylamine 25 mg)

Best for: Occasional trouble falling asleep

Its label lists doxylamine succinate 25 mg, 1 tablet 30 minutes before bed.

Watch out: Only take when you have time for a full night's sleep.

See options on Amazon

ZzzQuil Free and Clear liquid (diphenhydramine)

Best for: People who prefer a liquid

Its label lists diphenhydramine HCl 50 mg per 30 mL dose.

Watch out: Do not use with any other diphenhydramine product, even on skin.

See options on Amazon

ZzzQuil Ultra (doxylamine 25 mg)

Best for: A doxylamine tablet option

Its label lists doxylamine succinate 25 mg per tablet.

Watch out: Ask a doctor first if you have asthma or glaucoma.

See options on Amazon
When to talk to a doctor: See a doctor if sleeplessness lasts more than two weeks, or for loud snoring, gasping in sleep or daytime sleepiness. Ask a pharmacist before combining a sleep aid with other medicines.

Questions people ask

What is in OTC sleep aids?
Usually diphenhydramine or doxylamine succinate, both antihistamines, per the labels.
Is doxylamine or diphenhydramine better for sleep?
Both are labeled for occasional sleeplessness; choose with a pharmacist based on your health and other medicines.
How long can I take an OTC sleep aid?
Stop and ask a doctor if sleeplessness persists for more than two weeks.
Can I drink alcohol with a sleep aid?
No. The labels say avoid alcoholic beverages.
Can kids take ZzzQuil or Unisom?
No. The labels say do not use in children under 12.
When should I take a doxylamine sleep aid?
The labels say take one tablet 30 minutes before going to bed, only at bedtime, once daily.

Sources

Sources checked 2026-10-15.

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