What Is Unisom?

Updated April 17, 2017

Unisom is an over-the-counter brand of sleeping pill. Unisom can be used for occasional insomnia or difficulty in falling asleep. Unisom is not meant for long-term use.


There are three types of products under the Unisom brand: Unisom SleepTabs, Unisom SleepGels and Unisom SleepMelts. Unisom SleepTabs contain doxylamine succinate. Unisom SleepGels and Unisom SleepMelts both contain diphenhydramine HCl.


The doxylamine succinate contained in Unisom SleepTabs is an antihistamine. The diphenhydramine HCl in Unisom SleepGels and Unisom SleepMelts is also an antihistamine. Antihistamines are used to treat allergies and relieve sinus pressure. A side effect of antihistamines is drowsiness and sedation. Unisom SleepGels are an alternative for people who cannot swallow the Unisom SleepTabs. Unisom SleepMelts are cherry-flavoured meltable pills for people who cannot swallow any type of gel tabs or pills.


The sedative properties of antihistamines are useful for people who suffer from occasional insomnia or difficulty in falling asleep. Because the antihistamines in Unisom are non-narcotic, they may be seen as an alternative for people who do not want to take prescription sleeping pills, because of their possible addictive qualities.

Side Effects

Because antihistamines are used to treat sinus problems and allergies, the most common side effect of Unisom is dry mouth, dry nose or dry eyes. Other possible side effects include dizziness, headache, constipation and upset stomach. There are many other possible side effects from antihistamines; people who take Unisom should talk to their doctors if they are experiencing anything that might be a side effect of the drug.


Unisom should not be taken with alcohol, as this can increase the effects of drowsiness. Unisom should not be used by children under 12. Some people have allergies to antihistamines; these people should not use Unisom. Unisom can be secreted through breast milk, so pregnant women should talk to their doctors before using the drug.

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About the Author

Eve Lopez has 10 years of editorial experience at a variety of companies, including, "The Seattle Times" and She loves to travel and often writes about her travel experiences. Lopez earned a Bachelor of Arts in journalism from California State University and has been certified in TESOL (Teaching English to Speakers of Other Languages).