Is Benadryl Antihistamine Safe for Pregnant Women?

Updated May 13, 2019
Pregnant woman with pill in her hand

Though Benadryl is frequently used and is often recommended during pregnancy, its safety is uncertain. There are not enough human clinical studies to assess its risk completely. Use Benadryl only if getting relief from your symptoms outweigh any potential risks to your baby.

Safety During Pregnancy

Based on its U. S. Food and Drug Administration (FDA) category, Benadryl is not expected to cause harm to mothers or babies during pregnancy - but this is not known for sure. As with any drug, until further studies are done, use Benadryl during pregnancy only if it's necessary and you have no alternatives.

FDA Category

Diphenhydramine is rated pregnancy category B by the FDA. This means that either:

  • Animal studies did not show any risks to a developing fetus, but there are no well-designed clinical studies in pregnant women to prove its safety.
  • Animal studies showed harm, but well-designed human studies did not.

According to this category Benadryl has not been proven to be completely safe in pregnancy.

Other Forms of Benadryl

In addition to basic Benadryl with 25 mg of diphenhydramine, some formulations have medicines for pain relief or for sleep. The additions may add to the risk for you and your baby.

  • Total Benadryl Extra Allergy and Sinus has acetaminophen and pseudoephedrine in addition to diphenhydramine.
    • Acetaminophen is not assigned an FDA pregnancy category and is considered safe to take in small does for short-term use during pregnancy.
    • Pseudoephedrine may increase the risk for fetal malformations such as gastroschisis.
  • Benadryl-D Allergy Plus Sinus has phenylephrine added to relieve sinus congestion. Phenylephrine and diphenhydramine-phenylephrine combinations are assigned an FDA category C. There are no animal or human studies to prove the safety of phenylephrine, therefore avoid this combination.
  • Benadryl Allergy Nighttime to help with sleep has 50mgs of diphenhydramine instead of 25 mg, which will expose your baby to a higher dose of the medicine.
  • Topical Benadryl cream, spray or stick are used to treat a skin allergy or irritant reaction. Topical Benadryl can be absorbed through the skin but only minimal amounts will get into the blood stream.

Potential Risks of Benadryl

Most studies found that, in general, antihistamines use during pregnancy is not frequently associated with major birth malformations. However, there are not many studies that looked specifically at the risk of diphenhydramine, the Benadryl ingredient. Benadryl crosses the placenta, and it appears that the potential risks to a baby are primarily related its use during the first trimester.

The following studies summarize the potential risks to pregnant women taking Benadryl:

  1. The National Birth Defects Prevention Study (NBDPS) reported in Birth Defects Research Part A: Clinical and Molecular Teratology, February 2009. The authors looked at the risk to babies of several antihistamines taken during early pregnancy. Diphenhydramine was found to be associated with a greater risk for cleft lip, with or without cleft palate, and moderate risk for neural tube defects, spina bifida, gastroschisis, craniosynostosis and transverse limb deficiencies in eight cases.
  2. In a review study reported in the Journal of Allergy and Clinical Immunology, 2013, of 13,213 babies born with malformations, there was no association with antihistamine use; diphenhydramine being the most frequently used during the first trimester pregnancy.
  3. In the large U. S. Collaborative Perinatal Project reported in 1975, no major groups of malformations were associated with diphenhydramine use throughout pregnancy, though there were possible isolated malformations.
  4. There is evidence that in pregnant women, Benadryl has oxytocin-like actions on the pregnant uterus and could potentially initiate uterine contractions, especially if taken in large doses in the third trimester.

There is also evidence that Benadryl can cause side effects in a newborn including drowsiness and irritability if a pregnant woman uses it near delivery. Benadryl is also excreted in breast milk and should be used with caution if you plan to breastfeed.

Nurse listening to heartbeat of newborn in incubator

Possible Rare Risks Associated With Benadryl

While Benadryl is considered safe to take during pregnancy, there may be potential risks in the first and third trimesters. There have been rare associations to birth defects such as cleft palate when taking Benadryl during the first trimester but further studies are needed. If Benadryl is taken in high doses in the third trimester, there could be a potential oxytocin effect from the medication which can lead to contractions (as noted earlier). Therefore, Benadryl should be used cautiously and on a temporary, as-needed basis when pregnant. It should never be used for an extended period of time. Regardless, it is always advisable that you consult with your doctor prior to taking Benadryl.

Side Effects in Mothers

Benadryl's side effects include dryness of mouth, blurred vision, urinary retention and constipation. Urinary dysfunction and constipation are common problems for pregnant women, so Benadryl could add to these difficulties.

The sedating effect of Benadryl can cause dizziness, drowsiness and fatigue. Fatigue is a common symptom in pregnancy, so pregnant mothers should be careful not to drive while taking Benadryl. Also avoid taking it with other sleep medicines which might increase drowsiness as well as increase risk of fetal death.

Recommended Benadryl Dosage Allowed for Pregnant Women

There is a recommended Benadryl pregnancy dose for treatment of allergy symptoms such as, a runny nose, itching, sneezing or hives. Occasionally, a doctor may also prescribe Benadryl to pregnant women who are suffering from anxiety or may be having trouble sleeping. In the first trimester, a pregnant woman may be prescribed 25-50 mg of Benadryl by mouth once every six hours. In the second and third trimesters a pregnant woman should not take more than 25 mg of Benadryl every six hours.

Weigh the Risks and the Benefits

Because Benadryl is a familiar drug and easily accessible as an over-the-counter (OTC) medicine, many pregnant women might to choose to use it. Although Benadryl appears to carry few risks during pregnancy, there is not enough information to prove this and every drug should be considered potentially risky to a baby.

If you have severe allergy symptoms or an allergic skin reaction, before you use Benadryl (or any other OTC medicine) consider alternative treatment such as safe home remedies. Speak with your doctor about the benefits to you versus the potential risks to your baby for any drugs or remedies during pregnancy.

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Is Benadryl Antihistamine Safe for Pregnant Women?