Pyridoxine/doxylamine, sold under the brand name Diclectin among others, is a combination of pyridoxine hydrochloride (vitamin B6) and doxylamine succinate. It is generally used for nausea and vomiting of pregnancy (morning sickness); even though its efficacy has not been proven and subsequent research has led to the removal of recommendations in medical journals. Medical uses
The combination of pyridoxine, commonly referred to as vitamin B6 and doxylamine may be an effective for the management of nausea and vomiting of pregnancy, but it is only recommended for use in a small number of cases after lifestyle, diet and vitamin B6. A 2018 review found the benefit was small.Doxylamine and pyridoxine are pregnancy compatible drugs, consistent with FDAs safety assessment of the combination product. They have been categorized by the FDA as a category A drug (no evidence of risk to the fetus). This letter classification system for risk in pregnancy is no longer being utilized and is currently being phased out by the FDA. Medical organizations’ position
The American Congress of Obstetricians and Gynecologists (ACOG) states "Safe and effective treatments are available for more severe cases, and mild cases of nausea and vomiting of pregnancy may be resolved with lifestyle and dietary changes." The American Family Medicine recommends, "Initial treatment is conservative and includes dietary changes, emotional support, and vitamin B6 supplementation." This treatment has a Grade A, "consistent, good-quality patient-oriented evidence "  while the addition of prescribing doxylamine has a Grade C, "consensus, disease-oriented evidence, usual practice, expert opinion, or case series."
Since the mid-1950s, over 33 million women have used the combination drug of pyridoxine/doxylamine in pregnancy, and scientific analysis on more than 200,000 exposed pregnancies has been conducted to determine if the combination of pyridoxine and doxylamine is harmful to the unborn baby. No epidemiological studies have found any teratogenic effect.Two separate meta-analyses have been conducted that have assessed pregnancy outcomes following the use of a combination of pyridoxine and doxylamine with or without dicyclomine during the first trimester of pregnancy. The initial meta-analysis, published in 1988, combined data from 12 cohort and 5 case-control studies, and the subsequent meta-analysis, published in 1994, combined data from 16 cohort studies and 11 case control studies. These studies included over 200,000 Bendectin-exposed pregnancies and did not observe an increased risk for major malformations. Separate analyses were conducted for specific defects including cardiac defects, limb reduction defects, oral clefts, and genital tract malformations; no increased risks for these defects were found.In 1989, a report on the safety of the drug combination of pyridoxine/doxylamine for use in the management of NVP was prepared by a panel of Canadian and American experts for the Special Advisory Committee on Reproductive Physiology to the Health Protection Branch of Health Canada (currently called the Health Products and Food Branch). These scientific experts concluded that “numerous studies in animals and in humans that have been reported in the scientific and medical literature demonstrate that Bendectin is not a teratogen.