What are the effects of Diphenhydramine (Benadryl) during pregnancy?

From the Guidelines

Benadryl (diphenhydramine) should be used with caution during pregnancy, especially during the first trimester, due to potential concerns over its safety, although recent studies have not detected any increased risk for congenital malformations 1. When considering the use of diphenhydramine during pregnancy, it is essential to weigh the potential benefits against the potential risks. The evidence suggests that while diphenhydramine is often used by pregnant patients, there is still some concern over a case-control study suggesting an association with cleft palate that has yet to be sufficiently refuted 1. Some key points to consider when using diphenhydramine during pregnancy include:

• The standard adult dose is 25-50 mg every 4-6 hours, not exceeding 300 mg in 24 hours
• It is best to avoid regular or long-term use during pregnancy, especially during the first trimester
• Diphenhydramine can cause drowsiness in both the mother and potentially the developing fetus, which may affect the mother's ability to function safely
• Non-medication approaches for allergy relief should be tried first, such as avoiding allergens, using saline nasal sprays, or running an air purifier
• If allergies are severe or persistent during pregnancy, alternative medications with more pregnancy safety data, such as certain nasal steroid sprays or some second-generation antihistamines, may be recommended by a healthcare provider 1. It is also important to note that the safety of second-generation antihistamines used during the first trimester of pregnancy has been confirmed through large birth registries, case-control studies, and cohort studies, making them a potentially safer alternative to diphenhydramine 1.

From the FDA Drug Label

If pregnant or breast-feeding, ask a healthcare professional before use The effects of Diphenhydramine (Benadryl) during pregnancy are not explicitly stated in the drug label.

• The label advises pregnant individuals to ask a healthcare professional before use.
• No direct information is provided about the effects or safety of diphenhydramine during pregnancy 2.

From the Research

Effects of Diphenhydramine (Benadryl) during Pregnancy

• Diphenhydramine is an antihistamine that may be used during pregnancy for the treatment of allergic rhinitis, upper respiratory infections, urticaria/angioedema, atopic dermatitis, and as adjunctive treatment for anaphylaxis 3.
• The use of diphenhydramine during pregnancy should be approached with caution, as with any medication, and the benefits should outweigh the potential risks to the fetus 4, 5.
• There is limited information available on the specific effects of diphenhydramine during pregnancy, but it is known that antihistamines can cross the placenta and may affect the fetus 3.
• One study noted that a diphenhydramine preparation (Benadryl elixir) contains 15% alcohol, which may be a concern for fetal alcohol spectrum disorder, but most ethanol-containing medical preparations are considered safe during pregnancy 6.
• When prescribing diphenhydramine during pregnancy, it is essential to inform the patient of the possible risks and have her participate in making treatment decisions, and to monitor the fetus or neonate for adverse reactions during the course of treatment 5.

Key Considerations

• The risk-benefit situation should be carefully assessed, and the medication should only be used if the maternal benefits outweigh the potential fetal risks 4, 5.
• The dose and duration of therapy should be minimized to reduce the risk of adverse effects on the fetus 7, 5.
• Patients should be informed about the potential risks and benefits of diphenhydramine use during pregnancy, and they should be involved in the decision-making process 5.