Antihistamines are commonly used to relieve symptoms of allergic reactions, such as itching, sneezing, and runny nose. However, they are not typically used for prevention purposes. Antihistamines work by blocking histamine receptors in the body but do not prevent the initial allergic response. Other preventive measures, such as avoiding known allergens, are more appropriate for allergy prevention.

"You should take an antihistamine before being exposed to potential allergens to prevent an allergic reaction."
This response is incorrect because taking an antihistamine before exposure to potential allergens is not a standard recommendation for prevention. Antihistamines are typically used for symptom relief after an allergic reaction has occurred.

"Antihistamines should only be used after experiencing an allergic reaction, not for prevention."
This response is incorrect because antihistamines can be used for symptom relief after an allergic reaction, but they are not limited to post-reaction use only.

"Taking antihistamines regularly can increase your risk of developing allergies."
This response is incorrect because regular use of antihistamines does not increase the risk of developing allergies. Antihistamines are generally safe and effective for relieving allergy symptoms when used as directed.