What is the recommended dose of doxylamine (antihistamine) and vitamin B6 for hyperemesis gravidarum?

From the Guidelines

For hyperemesis gravidarum, the recommended dosage of doxylamine-pyridoxine (vitamin B6) combination is typically 10 mg doxylamine succinate plus 10 mg pyridoxine hydrochloride taken orally three to four times daily. This recommendation is based on the most recent and highest quality study available, which suggests that this combination is safe and effective for managing nausea and vomiting in pregnancy 1.

The treatment usually begins with one tablet at bedtime, then adding one tablet in the morning and another in the afternoon as needed to control symptoms. The maximum recommended daily dose is four tablets (40 mg doxylamine and 40 mg pyridoxine). This combination is available as the prescription medication Diclegis or Bonjesta in the United States. For patients without access to the combination product, separate components can be used: 12.5 mg doxylamine (half of a 25 mg over-the-counter Unisom SleepTabs) plus 10-25 mg pyridoxine three to four times daily.

Some key points to consider when using doxylamine and pyridoxine for hyperemesis gravidarum include:

• The antihistamine properties of doxylamine help reduce nausea, while vitamin B6 has been shown to independently improve pregnancy-related nausea 1.
• Treatment should be initiated early and continued as needed throughout pregnancy, with dosing adjusted based on symptom control and side effects, which may include drowsiness.
• The European Association for the Study of the Liver Clinical Practice Guidelines also recommend doxylamine and pyridoxine as first-line pharmacologic treatment of hyperemesis gravidarum 1.
• It is essential to monitor patients for potential side effects and adjust the treatment regimen as needed to ensure the best possible outcomes for both the mother and the fetus.

From the Research

Recommended Dose of Doxylamine and Vitamin B6

• The recommended dose of doxylamine and vitamin B6 for hyperemesis gravidarum is not explicitly stated in the provided studies, but it can be inferred from the information given.
• According to the study 2, the US Food and Drug Administration (FDA) approved doxylamine succinate 10 mg and pyridoxine hydrochloride 10 mg as a delayed-release combination pill called Diclegis for the treatment of nausea and vomiting in pregnancy.
• The study 3 mentions that Diclectin (doxylamine succinate 10 mg plus pyridoxine hydrochloride 10 mg slow release tablet) is more effective than placebo and ondansetron is more effective at reducing nausea than pyridoxine plus doxylamine.
• The study 4 also mentions that pyridoxine-doxylamine combination taken preemptively reduced risk of recurrence of moderate-severe symptoms compared with treatment once symptoms begin.

Treatment Options for Hyperemesis Gravidarum

• The study 5 suggests that initial pharmacologic treatment for hyperemesis gravidarum includes a combination of doxylamine and pyridoxine.
• Additional interventions include ondansetron or dopamine antagonists such as metoclopramide or promethazine.
• The study 6 presents a pathway for assessment and management of nausea and vomiting in pregnancy and hyperemesis gravidarum, which includes treatment with anti-emetics, acid suppression, and laxatives.

Safety and Efficacy of Doxylamine and Pyridoxine

• The study 2 addresses the historical context, safety, efficacy, pharmacology, and practical role of doxylamine and pyridoxine for the management of nausea and vomiting in pregnancy.
• The substantial amount of safety data accumulated over the years makes doxylamine and pyridoxine one of the few drugs that qualify for FDA Pregnancy Category A status.
• The combination of doxylamine and pyridoxine should be considered first-tier in the hierarchical approach to pharmacological treatment of nausea and vomiting in pregnancy 2.