A sedating antihistamine used for sleep and, with pyridoxine, for sickness in pregnancy
Doxylamine
A sedating antihistamine used as a short-term sleep aid and, combined with pyridoxine, to treat nausea and vomiting in pregnancy.
What is Doxylamine?
Doxylamine is a sedating antihistamine, meaning it causes drowsiness, which is why it is used as a short-term aid for sleep. Combined with pyridoxine (vitamin B6), it is also used to treat nausea and vomiting in pregnancy when simpler measures have not been enough. The main drawbacks are drowsiness and a hangover-like grogginess the next day, along with antimuscarinic effects such as a dry mouth, blurred vision and constipation. It is used short term, and care is needed about driving while feeling drowsy.
Education and reference only. This is a plain-language guide to Doxylamine — it deliberately contains no doses. Doses depend on the person, the brand and the reason for treatment, and belong with your prescriber. Always check the BNF, the product labelling (SmPC) and follow medical advice.
What it is
Doxylamine is an older, sedating antihistamine. Because it makes people sleepy, it is used as a short-term aid for getting to sleep. It also has a well-established role, when combined with pyridoxine (vitamin B6), in treating nausea and vomiting during pregnancy, where it is considered suitable when lifestyle measures alone are not enough. It comes as tablets, either on its own as a sleep aid or as a combined tablet with pyridoxine for pregnancy sickness. It is meant for short-term use rather than as a long-term treatment.
How it works
Doxylamine blocks histamine, a chemical involved in both allergy and in keeping the brain awake and alert. By blocking histamine in the brain, it brings on drowsiness, which is why it helps with sleep. Its anti-sickness effect, used in pregnancy alongside pyridoxine, is also linked to its action on histamine and on the part of the brain involved in nausea. Because it also blocks another chemical messenger (acetylcholine), it produces what are called antimuscarinic effects, such as a dry mouth and blurred vision, which explains several of its side effects.
Company & origin
Originated / developed by: Various manufacturers.
A long-established sedating antihistamine used in the UK as a short-term sleep aid and, combined with vitamin B6, for nausea and vomiting in pregnancy.
What it treats
Conditions Doxylamine is used for
Practical use
How to take Doxylamine
General, dose-free guidance — always follow your prescriber's and the leaflet's specific instructions.
- Use it short term, taking a sleep-aid dose before bed and allowing enough time for sleep before you need to be up.
- Be careful about driving or using machinery the next day, as drowsiness can linger.
- For pregnancy sickness, take the combined tablet with pyridoxine exactly as advised by your healthcare professional.
- Avoid alcohol while taking it, as this adds to the drowsiness.
- Do not rely on it night after night for sleep; it is meant for short-term use.
Weighing it up
Advantages & disadvantages of Doxylamine
Advantages
- Helps with getting to sleep in the short term because it causes drowsiness.
- When combined with pyridoxine, offers a well-established option for nausea and vomiting in pregnancy.
- Taken by mouth as a tablet and widely available.
Disadvantages
- Causes drowsiness and a next-day, hangover-like grogginess that can affect driving.
- Causes antimuscarinic effects such as a dry mouth, blurred vision, constipation and difficulty passing urine.
- Meant only for short-term use, and not suitable for everyone, particularly some older people.
Practical use
Good to know
The main thing to expect with doxylamine is drowsiness, which is the point of it as a sleep aid but can also leave a hangover-like grogginess the next morning that affects concentration and driving. Because it is long-acting, this next-day effect can catch people out, so care is needed about driving or operating machinery if you still feel drowsy. It also causes antimuscarinic effects such as a dry mouth, blurred vision, constipation and difficulty passing urine, which can be more troublesome in older people. It is intended for short-term use; relying on it night after night for sleep is not recommended. In pregnancy, the combination with pyridoxine is used when simpler steps have not controlled sickness, and it is taken as advised by a healthcare professional.
Who should not take it / use with caution
- People who have had a serious allergic reaction to doxylamine or similar antihistamines should not take it.
- It is used with caution, or avoided, in people with glaucoma, prostate problems or difficulty passing urine, because of its antimuscarinic effects.
- It is used with care in older people, who are more sensitive to drowsiness and confusion.
Monitoring
- Reviewing whether short-term use for sleep is still needed rather than continuing long term.
- Watching for daytime drowsiness, especially before driving or using machinery.
- In pregnancy, reviewing how well sickness is controlled and whether the treatment is still needed.
Side effects
- Drowsiness, and a hangover-like grogginess or poor concentration the next day.
- A dry mouth, blurred vision, constipation and difficulty passing urine.
- Dizziness, and in older people occasionally confusion.
Key interactions
- Alcohol and other medicines that cause drowsiness, such as some painkillers and sleep medicines, add to its sedating effect.
- Other medicines with antimuscarinic effects can add to the dry mouth, constipation and urinary problems.
- Tell your prescriber or pharmacist about all your medicines, including ones bought without a prescription.
Available as: Tablets, on their own as a sleep aid or combined with pyridoxine for pregnancy sickness.
Answers
Doxylamine: frequently asked questions
What is doxylamine used for?
It is a sedating antihistamine used as a short-term sleep aid and, combined with pyridoxine, to treat nausea and vomiting in pregnancy.
Why do I feel groggy the next day?
Doxylamine is long-acting, so its drowsiness can linger into the next morning as a hangover-like grogginess that can affect concentration and driving.
Is it safe to take in pregnancy?
Combined with pyridoxine, it is a well-established option for nausea and vomiting in pregnancy when simpler measures are not enough; take it as advised by your healthcare professional.
Can I drink alcohol with it?
No, alcohol adds to the drowsiness doxylamine causes, so it is best avoided while taking it.
Can I use it every night for sleep?
No, it is meant for short-term use; relying on it night after night is not recommended, so speak to your pharmacist or doctor about ongoing sleep problems.
The wider class
About Sedating antihistamine (sleep aid; pregnancy sickness)
Doxylamine belongs to the sedating antihistamine (sleep aid; pregnancy sickness) class. For how the class as a whole works, its shared safety principles and monitoring, see the full guide.
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Authoritative sources
- BNF
- NICE CKS
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