Over-the-counter H1-antihistamines

Loratadine

There are various generic and Claritin and Alavert formulations. The limited human data have generally shown no risk of teratogenicity. A Swedish study reported that exposure during pregnancy doubled the incidence of hypospadias (Int. J. Risk Saf. Med. 2001;14:115-9). However, a later study using data from the U.S. National Birth Defects Prevention Study found no association between loratadine and hypospadias (MMWR 2004;53:219-21).

In summary, the available evidence, both animal and human, indicates that as a class, H₁-antihistamines represent a low risk to the embryo and fetus. Because there are no reports for fexofenadine, other antihistamines might be a better choice. Although not discussed here, H₁-antihistamines are common components of upper respiratory formulations that contain decongestants, expectorants, or analgesics. Depending on the stage of gestation when used, these combinations may have a risk of maternal or fetal harm.

Breastfeeding

All of the above H₁-antihistamines are probably excreted into breast milk. Although published reports are rare, the first-generation agents have caused irritability or drowsiness in nursing infants. Fortunately, the second-generation agents have not been reported to cause these effects in a nursing neonate. Nevertheless, recommended doses of all of these agents are probably compatible with nursing full-term infants, but exposing preterm infants should be avoided.

Mr. Briggs is a pharmacist clinical specialist at the outpatient clinics of Memorial Care Center for Women at Miller Children’s Hospital in Long Beach, Calif.; clinical professor of pharmacy at the University of California, San Francisco; and adjunct professor of pharmacy at the University of Southern California, Los Angeles, and Washington State University, Spokane. He also is coauthor of "Drugs in Pregnancy and Lactation," and coeditor of "Diseases, Complications, and Drug Therapy in Obstetrics." He said he had no relevant financial disclosures. Contact him at obnews@frontlinemedcom.com. View more Drugs, Pregnancy, and Lactation columns by clicking here.