Doxylamine: Uses, Interactions and Safety

Uses

Doxylamine is a sedating first-generation antihistamine used for temporary difficulty falling asleep. This page covers single-ingredient oral sleep products. Products that combine doxylamine with pyridoxine for pregnancy-related nausea have different indications and instructions.

Administration

Use the exact local product instructions and allow time for a full night’s sleep. Take a sleep formulation only at bedtime. Do not combine several cold, allergy or sleep products without checking their ingredients. Turkish Unisom is for adults aged 18 and over; the New Zealand Dozile label does not recommend use below 12. These age limits are product-specific.

Safety

Doxylamine can impair driving and coordination into the next day. Older adults may be particularly sensitive. Discuss glaucoma, difficulty passing urine, an enlarged prostate, breathing disorders, epilepsy and kidney or liver disease before use. Turkish instructions call for medical assessment if insomnia lasts over two weeks; the New Zealand product is for occasional use no longer than a week.

Interactions

Other sleep medicines, benzodiazepines, opioids, sedating antihistamines and antipsychotics can increase drowsiness. Alcohol should be avoided. Antimuscarinic medicines and some antidepressants can increase constipation, blurred vision or urinary retention. MAO inhibitors may enhance antimuscarinic effects; these combinations require medication review.

Pregnancy and breastfeeding

Do not select a sleep product solely because doxylamine is also used in a pregnancy nausea combination. Pregnancy and breastfeeding advice differs between labels. Discuss the actual formulation with the clinician; breastfed infants may experience sedation or irritability.

Adverse effects

Reported effects include sleepiness, dry mouth, dizziness, constipation and urinary difficulty. Seek urgent help for impaired breathing, seizures, profound confusion or suspected overdose. Overdose can cause serious heart effects and muscle breakdown with kidney injury.

Sources

• DOZILE 25 mg capsules – New Zealand Datasheet (13 May 2019)
• Turkish product information: UNISOM 25 mg tablets
• ZYVOX (linezolid) – US prescribing information (Revised 6/2026; LAB-0139-46.0)