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Medical Author:

John P. Cunha, DO, FACOEP

John P. Cunha, DO, FACOEP

John P. Cunha, DO, is a U.S. board-certified Emergency Medicine Physician. Dr. Cunha's educational background includes a BS in Biology from Rutgers, the State University of New Jersey, and a DO from the Kansas City University of Medicine and Biosciences in Kansas City, MO. He completed residency training in Emergency Medicine at Newark Beth Israel Medical Center in Newark, New Jersey.

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Medical Editor:

William C. Shiel Jr., MD, FACP, FACR

William C. Shiel Jr., MD, FACP, FACR

Dr. Shiel received a Bachelor of Science degree with honors from the University of Notre Dame. There he was involved in research in radiation biology and received the Huisking Scholarship. After graduating from St. Louis University School of Medicine, he completed his Internal Medicine residency and Rheumatology fellowship at the University of California, Irvine. He is board-certified in Internal Medicine and Rheumatology.

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In this Article

• What is insomnia and what causes it?
• What are non-drug treatments for insomnia?
• Melatonin
• What over-the-counter (OTC) medicines are there for insomnia treatment?
• Antihistamines
• What prescription medicines are there for insomnia treatment?
• What stimulant products are available OTC?
• Caffeine
• Find a local Sleep Specialist in your town
• Sleep Aids And Stimulants Index

Self-treatment of insomnia with over-the-counter (OTC) drugs is advisable only for transient or short-term insomnia. OTC sleep aids should only be used for a short period of time in conjunction with changes in sleeping habits. Chronic use of these drugs may result in dependence on them. This creates a situation in which sleep is not possible unless the drug is used. Chronic insomnia should be evaluated by a physician.

Diphenhydramine (for example, Sominex, Nytol) and doxylamine (for example, Unisom) are antihistamines that are currently marketed as OTC sleep aids. Diphenhydramine is the only agent that is considered to be safe and effective by the Food and Drug Administration. Other uses for diphenhydramine include allergy, motion sickness, and cough suppression. Scientists believe that diphenhydramine and doxylamine cause sedation by blocking the action of histamine in the brain, but the exact mechanism of action is not known.

If insomnia is associated with pain, there are numerous products containing a combination of an antihistamine and pain reliever. These combination products should not be used if pain is not present because the added pain reliever is not necessary.

Pregnancy and lactation: The effects of diphenhydramine and doxylamine on the fetus have not been evaluated adequately. Diphenhydramine  is classified as a pregnancy "category B" drug, and is routinely safely used during pregnancy. Although the likelihood of an adverse effect on the fetus is low, sleeping agents probably should be avoided during pregnancy. Both agents may decrease lactation (production of milk). Additionally, these drugs are secreted into the breast milk, which could affect the newborn. Therefore, nursing mothers should also avoid both drugs. Consult a physician if you are pregnant and have insomnia.

Children: Children less than 12 years of age should not use doxylamine because its use in this in age group has not been assessed.

Elderly: Sedative effects of these drugs may interact with other potentially sedating medications. Consult a health care practitioner before using these drugs.

Drug interactions: Diphenhydramine and doxylamine add to the sedative effects of alcohol and other medications that cause drowsiness.

Side effects: Drowsiness is the most frequent side effect of both diphenhydramine and doxylamine. These agents should not be used in situations (for example, driving) where mental alertness is required. Diphenhydramine and doxylamine also cause constipation, dry mouth, and difficulty urinating. Both drugs may worsen the symptoms of glaucoma, asthma, heart problems, and prostate gland enlargement. People with these conditions should not use OTC sleep aids without consulting a physician.

Both drugs may paradoxically cause excitation, resulting in nervousness and insomnia. This occurs most often in children and the elderly.