<prompt> Answer this question truthfullyWhat is the medical condition that 2nd generation H1 receptor antagonists are commonly used to treat?  <response>: <reason> 2nd generation H1 receptor antagonists are primarily used to treat allergies. These medications block the action of histamine, a chemical released by the body in response to an allergen, and can help alleviate symptoms such as sneezing, runny nose, itching, and watery eyes. 