Is it OK to use over-the-counter antihistamines to treat insomnia? I'd like to avoid prescription sleep aids.
Answer From Eric J. Olson, M.D.
While some over-the-counter antihistamines can cause drowsiness, routinely using them to treat insomnia isn't recommended.
Antihistamines, mainly used to treat symptoms of hay fever or other allergies, can induce drowsiness by working against a chemical produced by the central nervous system (histamine). These medications can be useful in certain situations, such as for treating sleeplessness related to travel.
However, tolerance to the sedative effects of antihistamines can develop quickly. As a result, the longer you take them, the less likely they are to make you sleepy. Side effects might include daytime drowsiness, dry mouth and dizziness.
Also, the sedating antihistamines diphenhydramine and doxylamine have anticholinergic properties that make them poor choices for older adults. Research suggests that anticholinergics might increase the risk of dementia. In older adults these drugs also can cause confusion, hallucinations, dry mouth, blurred vision, constipation, nausea, impaired sweating, inability to empty the bladder completely (urinary retention) and rapid heart rate (tachycardia).
Diphenhydramine and doxylamine also aren't recommended for people who have closed-angle glaucoma, asthma, chronic obstructive pulmonary disease or severe liver disease.
If you're struggling with chronic insomnia, don't rely on antihistamines for a good night's sleep.
Oct. 16, 2019
See more Expert Answers
- Bonnet MH, et al. Behavioral and pharmacologic therapies for chronic insomnia in adults. https://www.uptodate.com/contents/search. Accessed Aug. 5, 2019.
- Kryger MH, et al., eds. Pharmacologic treatment of insomnia: Other medications. In: Principles and Practice of Sleep Medicine. 6th ed. Elsevier Saunders; 2017. https://www.clinicalkey.com. Accessed Aug. 5, 2019.
- Dauphinot V, et al. Anticholinergic drugs and functional, cognitive impairment and behavioral disturbances in patients from a memory clinic with subjective cognitive decline or neurocognitive disorders. Alzheimer's Research and Therapy. 2017; 10.1186/s13195-017-0284-4.
- Daroff RB, et al. Sleep and its disorders. In: Bradley's Neurology in Clinical Practice. 7th ed. Saunders Elsevier; 2016. https://www.clinicalkey.com. Accessed Aug. 5, 2019.
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