Antihistamines for morning sickness

Certain antihistamines such as doxylamine or dimenhydrinate, taken as your doctor advises, may relieve morning sickness.1 Doxylamine is a nonprescription medicine that is sold as Unisom Night-Time Sleep-Aid Tablets. If one of these antihistamines alone does not relieve your morning sickness, you can try taking it with vitamin B6.2

Vitamin B6 and doxylamine was prescribed as Bendectin in the U.S. until 1983, when it was taken off of the market. It has continued to be available in Canada as Diclectin. Although Bendectin was once thought to cause fetal problems, this medicine is now considered to have one of the best safety profiles of all medicines given during pregnancy, based on the tens of millions of women treated since 1956 with no known fetal effects.2, 3

Talk to your doctor about the right doxylamine dosage for you.

Note: Do not confuse Unisom Tablets with Unisom SleepGels, which contain a different medicine.


  1. Festin M (2007). Nausea and vomiting in pregnancy in early pregnancy, search date September 2006. Online version of BMJ Clinical Evidence. Also available online:
  2. Niebyl JR, Goodwin TM (2002). Overview of nausea and vomiting of pregnancy with an emphasis on vitamins and ginger. American Journal of Obstetrics and Gynecology, 186(5, Suppl): S253–S255.
  3. McKeigue PM, et al. (1994). Bendectin and birth defects: 1. A meta-analysis of the epidemiologic studies. Teratology, 50(1): 27–37.

Last Updated: November 28, 2008

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