Can I take promethazine while pregnant or breastfeeding?
A plain-words look at what the NHS, the US drug label and LactMed say about promethazine.
In short
Pregnancy: Promethazine can be taken while you're pregnant.
Breastfeeding: Promethazine can be taken while breastfeeding, as long as your baby is healthy. It's best to take it only now and then, or for a short time. Other medicines might be better, so check with your doctor or pharmacist first.
Your doctor, midwife or pharmacist can help you decide.
What this means for you
Pregnancy
- There's no evidence that it harms your baby, but it can cause side effects such as drowsiness (feeling sleepy).
- For hay fever, your doctor or pharmacist may suggest an antihistamine that does not cause drowsiness (loratadine).
Breastfeeding
- Promethazine can be taken while breastfeeding, as long as your baby is healthy.
- It's best to take it only now and then, or for a short time.
- Other medicines might be better, so check with your doctor or pharmacist first.
- How much promethazine reaches breast milk is not known, but the levels are likely to be low, and your baby will not be able to absorb much of it.
- It has been used by breastfeeding mothers for many years without causing side effects in their babies.
- However, promethazine is an antihistamine that causes drowsiness, and it may make your baby sleepy too.
- Promethazine products bought from a pharmacy may also include other ingredients.
- If you're breastfeeding, check with a doctor or pharmacist first.
- Side effects in breastfed babies from medicines their mother takes are very rare.
- Even so, it's important to keep an eye on your baby while you take any medicine and breastfeed.
- Carry on breastfeeding as normal until you've had advice about your baby's symptoms.
- While you're taking promethazine, it's important that you do not sleep in the same bed as your baby.
When to get help
- Contact a healthcare professional or call 111 (in the UK) as soon as you can if your baby is unusually sleepy; is not feeding as well, or not gaining weight, as you'd expect; or is irritable.
- If your baby has any other symptoms, or you're worried about them, you can still call 111 or get in touch with any healthcare professional.
Talk to your doctor or pharmacist
This page is educational, not advice for your own situation. Talk to your doctor, midwife or pharmacist before you start, stop or change any medicine in pregnancy or while breastfeeding.
The details: what each source says
Promethazine in pregnancy
The NHS says
Promethazine can be taken while you're pregnant. There's no evidence that it harms your baby, but it can cause side effects such as drowsiness (feeling sleepy).
For hay fever, your doctor or pharmacist may suggest an antihistamine that does not cause drowsiness (loratadine).
In our words, from the NHS page Promethazine (Phenergan) (nhs.uk). Contains public sector information licensed under the Open Government Licence v3.0 (OGL v3.0). The NHS does not endorse this site.
The US drug label says
Pregnancy Teratogenic Effects - Pregnancy Category C Teratogenic effects have not been demonstrated in rat-feeding studies at doses of 6.25 and 12.5 mg/kg of promethazine hydrochloride. These doses are from approximately 2.1 to 4.2 times the maximum recommended total daily dose of promethazine for a 50-kg subject, depending upon the indication for which the drug is prescribed. Daily doses of 25 mg/kg intraperitoneally have been found to produce fetal mortality in rats. Specific studies to test the action of the drug on parturition, lactation, and development of the animal neonate were not done, but a general preliminary study in rats indicated no effect on these parameters. Although antihistamines have been found to produce fetal mortality in rodents, the pharmacological effects of histamine in the rodent do not parallel those in man. There are no adequate and well-controlled studies of promethazine hydrochloride tablets, USP in pregnant women. Promethazine hydrochloride tablets, USP should be used during pregnancy only if the potential benefit justifies the potential risk to the fetus.
Prescribing label, section “Pregnancy” (opening excerpt): Promethazine Hydrochloride (oral), Redpharm Drug. Read the full section on DailyMed. Quoted verbatim; US labels are written for US prescribers and patients.
Promethazine while breastfeeding
The NHS says
Promethazine can be taken while breastfeeding, as long as your baby is healthy. It's best to take it only now and then, or for a short time. Other medicines might be better, so check with your doctor or pharmacist first.
How much promethazine reaches breast milk is not known, but the levels are likely to be low, and your baby will not be able to absorb much of it. It has been used by breastfeeding mothers for many years without causing side effects in their babies.
However, promethazine is an antihistamine that causes drowsiness, and it may make your baby sleepy too.
Promethazine products bought from a pharmacy may also include other ingredients. If you're breastfeeding, check with a doctor or pharmacist first.
Side effects in breastfed babies from medicines their mother takes are very rare. Even so, it's important to keep an eye on your baby while you take any medicine and breastfeed.
Contact a healthcare professional or call 111 (in the UK) as soon as you can if your baby is unusually sleepy; is not feeding as well, or not gaining weight, as you'd expect; or is irritable.
If your baby has any other symptoms, or you're worried about them, you can still call 111 or get in touch with any healthcare professional.
Carry on breastfeeding as normal until you've had advice about your baby's symptoms.
While you're taking promethazine, it's important that you do not sleep in the same bed as your baby.
In our words, from the NHS page Promethazine (Phenergan) (nhs.uk). Contains public sector information licensed under the Open Government Licence v3.0 (OGL v3.0). The NHS does not endorse this site.
LactMed says
Based on minimal excretion of other phenothiazine derivatives, it appears that occasional short-term use of promethazine for the treatment of nausea and vomiting poses little risk to the breastfed infant. With repeated doses, observe infants for excess sedation. Because promethazine can lower basal prolactin secretion, promethazine might interfere with the establishment of lactation if given during labor before lactation is well established or with a sympathomimetic such as pseudoephedrine. An antiemetic without potent histamine blocking action is preferred in nursing mothers.
“Summary of Use during Lactation”, LactMed record “Promethazine” (LM228), quoted verbatim. Everything LactMed reports about Promethazine while breastfeeding.
The US prescribing label says
Nursing Mothers It is not known whether promethazine hydrochloride is excreted in human milk. Because many drugs are excreted in human milk and because of the potential for serious adverse reactions in nursing infants from promethazine hydrochloride tablets, USP a decision should be made whether to discontinue nursing or to discontinue the drug, taking into account the importance of the drug to the mother.
Prescribing label, section “Nursing Mothers”: Promethazine Hydrochloride (oral), Redpharm Drug. Label on DailyMed. Quoted verbatim; US labels are written for US prescribers and patients.
Other names
UK brand names (per the NHS): Phenergan.
Sources
- NHS, Promethazine (Phenergan) (nhs.uk), page last reviewed 21 May 2025. Paraphrased. Contains public sector information licensed under the Open Government Licence v3.0.
- US drug label: Promethazine Hydrochloride (oral), Redpharm Drug, human prescription drug, label effective 2 September 2026, set ID 5a797d11-19b0-fd33-e063-6394a90a4d58. DailyMed (National Library of Medicine). Public domain; quoted verbatim.
- Drugs and Lactation Database (LactMed), National Institute of Child Health and Human Development (NICHD), via NCBI Bookshelf, record “Promethazine” (LM228), bulk release of 22 September 2026. LactMed on NCBI Bookshelf. Public domain; quoted verbatim. LactMed is a registered trademark of the U.S. Department of Health and Human Services.
Sources checked 26 September 2026. How we source and check every page.
Educational summary of named sources, not medical advice.