Diclectin (doxylamine/pyridoxine) scored the highest safety rating "A" in Briggs' reference guide on drugs in pregnancy and lactation

Diclectin® has been the subject of many epidemiological studies (cohort, case control and meta-analyses) designed to detect possible teratogenicity. Two separate meta-analyses have been conducted that have assessed pregnancy outcome following the use of a combination of doxylamine succinate, pyridoxine hydrochloride with or without dicyclomine hydrochloride during the first trimester. McKeigue et al. conducted a meta-analysis of 16 cohort and 11 case-control studies published between 1963 and 1991. No increased risk for malformations was found in first trimester exposures to doxylamine succinate and pyridoxine hydrochloride, with or without dicyclomine hydrochloride. A second meta-analysis, conducted by Einarson et al. incorporated 12 cohort and 5 case-control studies. No statistically significant relationships were found between first trimester use of the combination doxylamine succinate, pyridoxine hydrochloride with or without dicyclomine hydrochloride and fetal abnormalities.

In 1989, a report on the safety of Diclectin® for use in the management of nausea and vomiting of pregnancy was prepared by a panel of experts for the Special Advisory Committee on Reproductive Physiology to the Health Protection Branch of Health Canada. The Motherisk Program at the Hospital for Sick Children systematically reviewed the literature to develop an evidence-based algorithm on the safety and efficacy of treatments for nausea and vomiting of pregnancy. Doxylamine succinate combined with pyridoxine hydrochloride (Diclectin®) is listed as first line therapy on this algorithm. Similarly, the 2002 Society of Obstetricians and Gynaecologists of Canada (SOGC) Clinical Practice Guidelines on the management of nausea and vomiting of pregnancy recommend that this formulation be the standard of care, since it has the greatest evidence to support its safety and efficacy.