Summary. Benadryl (diphenhydramine) is classified as pregnancy Category B medication. This means that there is probably no danger to the baby with this medication. US FDA pregnancy category B: Animal reproduction studies have failed to demonstrate a risk to the fetus and there are no adequate and well-controlled studies in pregnant women. Use is recommended only if clearly needed and the benefit outweighs the risk. Antihistamines are one of the most common drugs that are used extensively in various dermatological and nondermatological conditions. The use of H-1-antihistamines during pregnancy has been very controversial due to possible teratogenic effects of these drugs. Category B. Either animal reproduction studies have not demonstrated a fetal risk but there are no controlled studies in pregnant women, or animal reproduction studies have shown an adverse effect. Benadryl’s Pregnancy Risk Category. Benadryl, also known as diphenhydramine, is considered a Class B category drug. Medications are labeled as Category B by the FDA when no adverse effects are found on the fetus when studied on pregnant animals. Benadryl FDA Pregnancy Category. Category B – Diphenhydramine does cross the placenta but animal studies show little evidence of harmful effects on the fetus. Diphenhydramine is category B in the FDA Classification of Drug Safety During Pregnancy. It is also excreted in breast milk. [32] Paradoxical reactions to diphenhydramine have been documented, in particular among children, and it may cause excitation instead of sedation. Find yourself needing help relieving allergies or a pesky itch? Check out the many allergy and itch relief products BENADRYL® offers which may help provide relief. Benadryl (diphenhydramine) is an antihistamine that reduces the effects of natural chemical histamine in the body. Histamine can produce symptoms of sneezing, itching, watery eyes, and runny nose.