After diet changes, it alone is recommended as the secondary treatment plan. The most commonly reported adverse reaction of doxylamine is drowsiness. Other adverse drug reactions associated with doxylamine succinate may include: vertigo, nervousness, epigastric pain, headache, palpitation, diarrhea, disorientation, irritability, convulsions, urinary retention or insomnia.It is not recommended to take  doxylamine with other medications of the same class, medications that act on the central nervous system (CNS) or with alcohol as this may increase the risk of adverse effects. To minimize the risk of particular adverse effects, doxylamine should not be used when taking any medication classified as a monoamine oxidase inhibitor (MAOI), and should be used with caution, if at all, when certain medical conditions are present.Because doxylamine is small enough on a molecular weight basis to pass into breastmilk, women should not breastfeed while using products with doxylamine as this may lead to adverse effects in the breastfed infant. Safety in pregnancy
Due to the extensive scientific evidence demonstrating that there is no difference in the risk for birth defects or other adverse pregnancy outcomes between infants whose mothers take pyridoxine/doxylamine during pregnancy and those infants whose mothers do not take this drug combination, the two ingredients of the drug are considered pregnancy compatible (or category A drugs with the previous pregnancy risk factor classification system).
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."