Doxylamine with pyridoxine

How it works

Doxylamine is an H1-antihistamine with antiemetic and sedative properties, while pyridoxine (vitamin B6) is thought to contribute an additional antiemetic effect; the combination relieves pregnancy-related nausea.

Prescribing in practice

• Warn that the doxylamine component is sedating and may impair the ability to drive or operate machinery, with additive effects when combined with alcohol or other CNS depressants.
• It is generally used when conservative measures fail to control nausea and vomiting of pregnancy.
• Avoid concurrent use with monoamine oxidase inhibitors and use caution in conditions where antimuscarinic effects are problematic, such as narrow-angle glaucoma.

Monitoring

Routine laboratory monitoring is not required; review symptom control and degree of sedation and reassess if vomiting is severe or persistent.

Counselling the patient

• Drowsiness is common, so avoid driving or operating machinery until you know how it affects you.
• Avoid alcohol while taking this medicine.
• Seek urgent review if you cannot keep fluids down or show signs of dehydration.

Evidence & guidelines

A modified-release doxylamine-pyridoxine combination is supported for nausea and vomiting of pregnancy and is reflected in UK guidance on managing this condition.