Loratadine (also known as Claritin) is an allergy medication that is considered safe, based on animal studies that have shown no risks to the fetus and no reports of human reproductive problems. However, it has not been adequately tested in human pregnancy to fully guarantee its safety.
Because drugs aren’t studied in pregnant women for fear of harming the baby inside the womb, doctors prescribe medicine based on the best available scientific evidence. Taking any drugs during pregnancy requires extra caution, especially because very few drugs have actually been proven safe for pregnant women. Consult your doctor to weigh the pros and cons of taking Claritin or other allergy drugs, and taking the possible risks to your fetus as a primary consideration.
Check for FDA warnings on drug labels; it is mandatory to indicate if a drug poses a risk of birth defects or any adverse effects on reproduction or pregnancy.