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Diphenhydramine (Benadryl®)

Last Update: 20 Jun 2025

Welcome to our fact sheet on diphenhydramine during pregnancy and breastfeeding/chestfeeding. This information is based on available published literature. It should not take the place of medical care and advice from your healthcare provider.

The HEALTHY PREGNANCY HUB team is collaborating with MotherToBaby to share information on this topic. The original version is available here (December 2024).

Serene, our chatbot, can also answer your questions about medications during pregnancy.

Please note that this fact sheet is based on United States information and has been adapted for Canada, with a review by our Canadian experts. Minor differences may exist between the two countries. Always consult your healthcare professional for information tailored to your situation.

1. What is nitrofurantoin?

Diphenhydramine is an antihistamine medication that has been used to treat allergy symptoms, nausea, motion sickness, insomnia, itchy skin, migraine, and tremors related to Parkinson’s disease. Diphenhydramine is found in many prescriptions and over the counter products. Some brand names for diphenhydramine include Benadryl®, Unisom®, Sominex®, ZzzQuil®, and Nytol®.

Sometimes when people find out they are pregnant, they think about changing how they take their medication, or stopping their medication altogether. However, it is important to talk with your healthcare providers before making any changes to how you take your medication. Your healthcare providers can talk with you about the benefits of treating your condition and the risks of untreated illness during pregnancy. 

2. What does research say about the risks during pregnancy?

I take diphenhydramine. Can it make it harder for me to get pregnant?

It is not known if diphenhydramine can make it harder to get pregnant. 

Does taking diphenhydramine increase the chance of miscarriage?

Miscarriage is common and can occur in any pregnancy for many different reasons. Results from one study did not show an increased chance of miscarriage with the use of antihistamines, including diphenhydramine, in early pregnancy. 

Does taking diphenhydramine increase the chance of birth defects?

Birth defects can happen in any pregnancy for different reasons. Out of all babies born each year, about 3 out of 100 (3%) will have a birth defect. We look at research studies to try to understand if an exposure, like diphenhydramine, might increase the chance of birth defects in a pregnancy. 

A few studies have suggested a higher chance for birth defects when diphenhydramine is used during the first trimester. However, these studies do not all agree, and no consistent pattern of birth defects has been noted. There are also several studies that reported no increased chance of birth defects with the use of diphenhydramine in early pregnancy. 

Does taking diphenhydramine in pregnancy increase the chance of other pregnancy-related problems?

Occasional use of diphenhydramine at recommended doses is not expected to increase the chance of other pregnancy-related problems, such as preterm delivery (birth before week 37) or low birth weight (weighing less than 5 pounds, 8 ounces [2500 grams] at birth). 

There are reports of other issues, including uterine contractions and, very rarely, fetal death with the use of diphenhydramine in the third trimester. However, these reports usually involve using more of the medication than is recommended or using it for longer than the recommended time. 

Can I take diphenhydramine with a benzodiazepine? 

There is a single human report and some animal data that has suggested that the combination of a medication called temazepam (a benzodiazepine) and diphenhydramine might increase the chance of stillbirth or infant death shortly after birth. It has been recommended that these two medications not be used together during pregnancy. People who take temazepam should talk with their healthcare provider before taking diphenhydramine during their pregnancy. MotherToBaby has a fact sheet on temazepam here. 

I need to take diphenhydramine throughout my entire pregnancy. Will it cause withdrawal symptoms in my baby after birth?

The use of diphenhydramine during pregnancy can cause temporary symptoms in newborns soon after birth. These symptoms are sometimes referred to as withdrawal. There are a few reports of withdrawal symptoms (tremors and diarrhea) in infants who were exposed to diphenhydramine daily throughout pregnancy. Not all babies exposed to diphenhydramine will have these symptoms. It is important that your healthcare providers know you are taking diphenhydramine so that if symptoms occur your baby can get the care that is best for them. 

Does taking diphenhydramine in pregnancy affect future behavior or learning for the child?

It is not known if diphenhydramine increases the chance for behavior or learning issues. 

3. Breastfeeding​ or chestfeeding​ while taking diphenhydramine

Diphenhydramine passes into human milk in small amounts. This medication can cause sleepiness in adults as well as the nursing baby. Two studies that looked at the use of antihistamines such as diphenhydramine while breastfeeding or chestfeeding reported that exposed babies were irritable, sleepier, and/or slept less. Short-term or occasional use of diphenhydramine is not expected to increase the chance of side effects during nursing. If you need to take an antihistamine regularly, ask your healthcare provider about which medication is best for you. Be sure to talk to your healthcare provider about all your breastfeeding or chestfeeding questions. 

4. What about fathers and sperm donors?

If a male takes diphenhydramine, could it affect fertility or increase the chance of birth defects?

Studies have not been done to see if diphenhydramine could affect a male’s fertility (ability to get a partner pregnant) or increase the chance of birth defects above the background risk. In general, exposures that fathers or sperm donors have are unlikely to increase risks to a pregnancy. For more information, please see the MotherToBaby fact sheet Paternal Exposures here.

Key points

  • Diphenhydramine (Benadryl®) is an antihistamine used to treat allergies, nausea, trouble sleeping, itchy skin, and motion sickness. It can be found with and without prescription.
  • Most studies do not show a higher risk of miscarriage, birth defects, or preterm birth when diphenhydramine is taken during pregnancy.
  • Taking high doses of diphenhydramine or using it for a long time, especially in the third trimester, may be linked to problems in the baby, but this is rare.
  • Diphenhydramine can pass into human milk in small amount and may make the baby sleepy or irritable. Short-term use is not expected to cause problems.
  • There are no studies on the risks of fertility or birth defects when diphenhydramine is taken by fathers or sperm donors.
  • Always consult your healthcare professional before starting or making any changes to your allergy treatment during pregnancy or breastfeeding/chestfeeding.

References

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Disclaimer

HEALTHY PREGNANCY HUB provides a source of information validated by health professionals; however, this information is provided for informational purposes only and should not replace professional advice. Medical standards and practices evolve as new data becomes available, so it is imperative to consult your doctor or a qualified health professional for any questions or concerns regarding your health without delay or omission. It is the responsibility of your treating physician or any other health professional, based on their independent experience and knowledge of the patient, to determine the best way to evaluate and treat you.

HEALTHY PREGNANCY HUB does not specifically recommend or endorse any test, practitioner, treatment, product, or opinion mentioned on our platform. HEALTHY PREGNANCY HUB also does not replace the individual patient assessment based on the examination by the healthcare provider of each patient and the consideration of laboratory data and other patient-specific factors.

The use of the information available on our site is at your own risk. No person involved in the creation, production, promotion, or marketing of HEALTHY PREGNANCY HUB guarantees or represents, expressly or implicitly, anything regarding the information available on the platform, which is provided “as it is”. All warranties are expressly excluded and disclaimed, including but not limited to implied warranties of merchantability or fitness for a particular purpose, as well as any warranties arising by law or otherwise in law or from trade or usage. Any statements or representations made by any other person or entity are void.

While consulting symptoms or other medical information on our platform may guide your discussions with your healthcare professional, this information should not be used to make a medical diagnosis or determine treatment. Before making changes to your supplement or medication regimen, please discuss with your medical team or contact 811 (Canada) to ensure the relevance of these changes to your individual situation.

Credits
MotherToBaby
Organization of Teratology Information Specialists (OTIS)
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Émy Roberge
Centre hospitalier universitaire Sainte-Justine
Evelyne Rey
CHU Sainte-Justine
Brigitte Martin
Centre Hospitalier Universitaire Sainte-Justine
Sherif Eltonsy
University of Manitoba
Sacha Williams
McGill University
Modupe Tunde-Byass
University of Toronto

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