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Doxylamine/pyridoxine for nausea and vomiting in pregnancy

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Generic name: Doxylamine succinate and pyridoxine hydrochloride

Brand name: Xonvea

Formulation: Gastro-resistant tablets containing 10 mg doxylamine succinate and 10 mg pyridoxine hydrochloride

Market authorisation holder: Alliance Pharmaceuticals Limited

Indication: The treatment of nausea and vomiting of pregnancy in women who do not respond to conservative management.

Dose: Two tablets at bedtime. Maximum recommended daily dose is four tablets. It should be taken daily and not on an as needed basis.

Cost: 20 tablets = £28.50

Classification: Prescription only medicine (POM)

Key learning points

  • A combination of doxylamine and pyridoxine (vitamin B6) is licensed for the treatment of nausea and vomiting in pregnancy when conservative management has not worked.

  • This is the first antiemetic to be licensed in the UK for the management of nausea and vomiting in pregnancy.

  • The marketing authorisation application included data for this formulation and a previously marketed product that contained the same active components.

  • A clinical trial has demonstrated that the combination of doxylamine and pyridoxine produced small but statistically significant differences in symptoms and well-being compared with placebo.

  • Common or very common adverse effects include dizziness, drowsiness, dry mouth and fatigue.

  • We are not aware of any high-quality evidence that shows that the combination of doxylamine and pyridoxine is more effective than other antiemetics.


Nausea and vomiting in pregnancy (NVP) is common and varies considerably in duration and severity.1,2 It affects 50%–90% of pregnant women and causes clinically significant symptoms in about one-third of these women.3 Hyperemesis gravidarum, which affects around 1% of pregnant women, represents the extreme end of the spectrum and is associated with weight loss of more than 5% of pre-pregnancy weight, dehydration, electrolyte imbalances, ketosis and the need for intravenous fluid management. The causes of NVP are likely to involve hormonal, genetic and gastrointestinal factors.

NVP typically starts between weeks …

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  • Competing interests None declared.

  • Provenance and peer review Written by the DTB team; externally peer reviewed.