Desensitizers usually refer to antihistamines such as cetirizine, loratadine, azelastine, etc. Pregnant women who develop allergic rhinitis need to be cautious about using these drugs. According to the U.S. Classification of Safe Use of Medications in Pregnancy, antihistamines such as cetirizine and loratadine belong to Class B, and azelastine belongs to Class C. Class B drugs are drugs that have not been proven to be harmful to the fetus in humans or are harmless to the fetus in animal studies but have not been adequately investigated in humans, and Class C drugs refer to drugs that can’t be excluded from being harmful, but the benefits to the pregnant woman outweigh the harms to the fetus. When a pregnant woman develops allergic rhinitis, she needs to stay away from allergens to facilitate symptom relief. If the symptoms continue to be unable to relieve, it is recommended to seek medical attention, if you need to use medication, under the guidance of a doctor, avoid unauthorized use of drugs to prevent the impact on the fetus.