This sheet talks about using diphenhydramine in a pregnancy and while breastfeeding. This information should not take the place of medical care and advice from your healthcare provider.

What is diphenhydramine?

Diphenhydramine is an antihistamine. It is found in many medications, both prescription and over-the-counter. It is commonly used to treat allergy symptoms, and may also be used to treat nausea, motion sickness, insomnia, itchy skin, and tremor of Parkinson’s disease. Some of the brand names for diphenhydramine include: Benadryl®, Unisom®, Sominex®, or Nytol®.

I just found out I am pregnant. Should I stop taking diphenhydramine?

You should always talk with your health care provider before making any changes in your medication. It is important to consider the benefits of treating your condition during pregnancy.

Can taking diphenhydramine during my pregnancy increase the chance of miscarriage?

Miscarriage can occur in any pregnancy. There are no published studies looking at whether diphenhydramine increases the chance of miscarriage. This does not mean there is an increased chance or that there is no increased chance, it only means that this question has not been answered.

Can use of diphenhydramine during pregnancy cause birth defects?

In every pregnancy, a woman starts out with a 3-5% chance of having a baby with a birth defect.  This is called her background risk. A few studies have suggested a higher chance for birth defects when diphenhydramine is used during the first trimester. However, the studies do not all agree and no consistent pattern of birth defects has been noted. In addition, several studies showed no increased chance of birth defects with the use of diphenhydramine in early pregnancy. Based on current research, it is unlikely that diphenhydramine would cause an increased chance for birth defects.

Can use of diphenhydramine cause other pregnancy complications?

Occasional use of diphenhydramine at recommended doses have not been shown to cause problems in pregnancy. There are rare reports of problems with the use of diphenhydramine in the third trimester. These reports usually involve using more of the medication than is recommended or using it for long-term (chronic) use. High levels of diphenhydramine could cause uterine hyperstimulation (contractions that are too long or too often). Uterine contractions can also lead to serious complications, including preterm delivery, uterine rupture (a tear in the uterus) or placental abruption (when the placenta pulls away from the wall of the uterus before the baby is born).

Also, there are a few reports of withdrawal symptoms (tremors and diarrhea) in infants whose mothers took diphenhydramine daily throughout pregnancy.

Is there anyone who should avoid taking diphenhydramine during pregnancy?

A single human report and animal data have suggested that the combination of two medications: temazepam (a benzodiazepine) and diphenhydramine might increase the chance for stillbirth or infant death shortly after birth. It is unknown if this interaction will occur with all medications in the benzodiazepine class. Women taking benzodiazepines should talk with their healthcare provider before taking diphenhydramine during their pregnancy. For more information, see the MotherToBaby fact sheet on benzodiazepines at: https://mothertobaby.org/fact-sheets/benzodiazepines-pregnancy/pdf/.

Can I breastfeed while taking diphenhydramine?

Diphenhydramine has not been well studied for use in breastfeeding. However, it is likely that some of the medication would pass into the breastmilk. In addition, because diphenhydramine can cause sleepiness in adults, it may do the same for a nusring baby. If you need to take an antihistamine regularly, ask your health careprovider if a non-sedating medication would work for your symptoms.

Antihistamines as a group might lower the amount of milk a woman makes, especially when using long acting antihistamines and when used with decongestants like pseudoephedrine or phenylephrine. This is less likely to be of concern in a woman with established milk supply (has been breastfeeding for a while).

Two studies of women who used an antihistamine such as diphenhydramine while breastfeeding reported their babies were irritable, sleepier, and/or slept less.

Be sure to discuss any medications you are taking and your options for breastfeeding with your health careprovider as well as the baby’s pediatrician.

What if the father of the baby takes diphenhydramine?

There are no studies looking to see if a man’s diphenhydramine use would cause any problems for conceiving or problems during a partner’s pregnancy. In general, exposures that fathers have are unlikely to increase risks to a pregnancy. For more information, please see the MotherToBaby fact sheet Paternal Exposures and Pregnancy at: https://mothertobaby.org/fact-sheets/paternal-exposures-pregnancy/pdf/.

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