Antihistamines can relax smooth muscles and decrease what?

The ability of antihistamines to relax smooth muscles is primarily linked to their role in managing allergic reactions and other similar conditions. Antihistamines work by blocking the action of histamine, a chemical in the body that is involved in producing symptoms of allergies. When histamine is released during an allergic reaction, it can lead to symptoms such as itching, increased bodily secretions (like mucus), and other discomforts.

By inhibiting histamine's effects, antihistamines effectively reduce these symptoms, including the sensation of itching and the secretion of mucus. This makes antihistamines particularly useful for treating conditions such as hay fever, allergic rhinitis, and urticaria where these symptoms are prevalent.

In contrast, while antihistamines may have some impact on airway inflammation, they are not primarily used for that purpose. Their primary function is to mitigate symptoms related to histaminic reactions, which include itching and attributes resulting from increased bodily secretions. Thus, the reduction of itching and bodily secretions is the most accurate outcome of antihistamine use.