Over-the-counter medications for the treatment of a sleep problem are those that can be purchased without a prescription. Examples of popular over-the-counter sleep aids include:

  • Sleep-Eze
  • Sominex
  • Nytol
  • Unisom and others

OTC sleep medications should only be used on a short term basis, since extended use of these medications can actually exacerbate insomnia. According to the American Academy of Sleep Medicine, antihistamine (usually diphenhydramine hydrochloride or doxylamine succinate) is the most common ingredient in OTC sleep aids.

The OTC sleep medications rely on the sedating effects of the antihistamine to facilitate sleep. If patients attempt to use an OTC sleep aid, they should immediately discontinue use if they experience any adverse side effects such as:

  • Dry mouth
  • Dry eyes
  • Urinary retention
  • Confusion (especially in the elderly)
  • Drowsiness the following day
  • Forgetfulness
  • Constipation
  • Blurred vision

Tolerance to the sedative effects of antihistamines can develop quickly—the longer they are taken the less likely they are to induce sleep. Many over-the-counter sleep aids can result in the person feeling groggy and unwell the next day. This is the so-called hangover effect. Also, these sleep medications may interact negatively with other medications, so a doctor should be consulted prior to using these for a sleeping problem.


It should also be noted that the sleep that is experienced when taking over-the-counter sleeping aids is not of the same quality as normal sleep. Research has demonstrated that some people who take OTC sleep aids spend as little as 5 percent of their total sleep time in deep sleep as compared to approximately 10 percent to 25 percent in healthy sleepers.

See Chronic Pain and Insomnia: Breaking the Cycle

Diphenhydramine or Doxylamine?

Since almost all OTC sleep aides contain either diphenhydramine hydrochloride or doxylamine succinate, the choice is basically between these two active ingredients. The following information may help in making an informed decision between these two medications.



Diphenhydramine is eliminated quickly from the body and most individuals don’t experience any lingering grogginess from the medicine the next day. Tolerance to this particular antihistamine builds up quickly and it loses its effectiveness as a sleep aid after just a few nights of repeated use. In general, diphenhydramine is less expensive than doxylamine. Since its use is associated with less of a hangover effect, and is milder than doxylamine, it is usually a good first choice in this category of and OTC sleep aid.

  • Diphenhydramine is the active ingredient in Sleep Eze, Sominex, Nytol, Tylenol PM, and Unisom SleepGels

Doxylamine succinate

Doxylamine succinate is one of the most sedating antihistamines available over-the-counter (stronger than diphenhydramine). A single dose causes rapid and marked drowsiness in the vast majority of individuals. Doxylamine succinate is eliminated somewhat more slowly from the body than diphenhydramine hydrochloride. As such, it will help the individual stay asleep longer but also may have a “hangover” effect the next day. Unlike diphenhydramine, most people don’t develop a tolerance to the sedating effects of doxylamine succinate.

  • Doxylamine is the active ingredient in Kirkland Sleep Aid (Costco) and Unisom SleepTabs

Dr. William Deardorff is a clinical health psychologist and specializes in providing psychological services to patients with chronic pain and spinal conditions. He has led a private practice for more than 30 years.