Doxylamine Not Recommended as Long-Term Insomnia Treatment

Found in Unisom and Nyquil, Doxylamine Causes Sleepiness as a Side Effect

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Doxylamine is found in over-the-counter products such as Unisom and Nyquil. It may be taken to treat insomnia, but is this the best treatment option for this condition? Like the related medication diphenhydramine, doxylamine does not require a prescription. What should you consider before using this medication, and what alternative sleeping pills may work better? Learn about the use of doxylamine in treating insomnia.

Uses of Doxylamine

Doxylamine may be helpful for treating allergies, but a side effect is that it causes drowsiness. Some people will therefore take it to help with symptoms of insomnia -- a difficulty falling or staying asleep. It's sometimes taken to help initiate or maintain sleep, and also for nighttime relief of symptoms related to the common cold. It shouldn't be used for more than 2 weeks to treat insomnia.

How Does Doxylamine Work?

Doxylamine is one of the medications known as an antihistamine. Like many sleeping pills, it affects neurotransmitters: specialized chemical messengers that act within the brain and between nerve cells and other tissues. It blocks the uptake of histamine into cells, so hystamine consequently builds up, leading to sleepiness. Doxylamine works centrally within the brain, where it causes sedation, and elsewhere in the body.

Who Should Not Use Doxylamine?

Young children under 2 years of age should not use doxylamine, nor should it be used by women who are breastfeeding, as it may pass through the milk to an infant.

There are many conditions in which you should only use doxylamine cautiously. If you're concerned about whether you may have problems using it, you should first consult with your doctor. If you suffer from conditions that increase your eye pressure, such as glaucoma, you may need to exercise caution.

Other conditions that may be problematic include:

  • hyperthyroidism
  • heart disease
  • high blood pressure
  • asthma
  • chronic obstructive pulmonary disease
  • pneumonia
  • peptic ulcer disease
  • prostate enlargement
  • liver disease
  • bowel or bladder obstruction

In addition, children under 6, and elderly patients, should use caution if taking this drug.

There is also a risk for drug interactions, including with medications that affect the brain, so be sure to review your medications with your doctor or pharmacist before starting to use doxylamine.

What Are Common Side Effects of Doxylamine?

The list of potential side effects for any drug can be quite long, and doxylamine is no exception. Although you likely wouldn't experience most side effects -- and may not have any at all -- some that occur commonly with doxylamine include:

  • Drowsiness
  • Dizziness
  • Loss of coordination
  • Headache
  • Stomach pain
  • Thick lung secretions
  • Dry mouth or nose
  • Hyperactivity
  • Constipation
  • Difficulty urinating
  • Low blood pressure
  • Blurred or double vision
  • Rapid or irregular heart rate
  • Sensitivity to light
  • Sweating
  • Erectile dysfunction

What Are Potential Serious Reactions?

There are also risks of serious side effects with the use of doxylamine. These effects occur more rarely:

  • Severe allergic reaction including difficulty breathing (anaphylaxis)
  • Low blood cell counts (agranulocytosis, anemia, thrombocytopenia, and leukopenia)
  • Abnormal heart rhythms
  • Seizures
  • Toxic psychosis
  • Inner ear problems (Acute labyrinthitis)

Things to Keep in Mind

Certain individuals should use doxylamine carefully or not at all, as described above. As an over-the-counter medication, the risks are thought to be slightly less compared to other prescription medications that require more careful monitoring. There are no routine tests recommended with its use.

Ultimately, doxylamine is not the best option if you are considering taking sleeping pills; there are a number of other choices that are better suited to aiding sleep.

To take a medication for its side effect -- in this case, sleepiness -- is not recommended. It doesn't promote sleep the way other prescribed hypnotic medications can, including benzodiazepine and non-benzodiazepine medications. It may ultimately lead to further sleep disruption, including worsened insomnia, or even dependence.

If you experience any difficulties when taking this drug, you should be in close contact with your primary health provider. If you wish to pursue preferred treatments for insomnia, you should likewise make an appointment and discuss the better prescription options that are available.


"Doxylamine." Epocrates Rx Pro. Version 3.4, 2010. Epocrates, Inc. San Mateo, California.

"Doxylamine." PubMed Health. May 16, 2011. Last accessed: October 31, 2012.

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