Question: how much diphenhydramine is safe during pregnancy?
Answer: When you're pregnant you can take the same dose of Benadryl as before pregnancy. For standard Benadryl, that means no more than 1 to 2 tablets every 4 to 6 hours for an adult. Some small, older studies suggested that taking Benadryl the first trimester of pregnancy could lead to a slightly higher risk of birth defects.