For which condition is diphenhydramine indicated for use?

Diphenhydramine, an antihistamine, is indicated for the treatment of urticaria, commonly known as hives. This condition is characterized by the presence of itchy, raised welts on the skin, often caused by an allergic reaction. Diphenhydramine works by blocking the action of histamine, a substance in the body that contributes to allergic symptoms, thereby reducing the itchiness and swelling associated with hives.

In contrast, while asthma is also an allergic condition, it typically requires bronchodilators or corticosteroids rather than antihistamines for effective management. Hypertension and diabetes are unrelated to the antihistamine effects of diphenhydramine and are treated with different classes of medications altogether. Therefore, using diphenhydramine for these conditions would not be appropriate or effective, highlighting why urticaria is the correct choice for its indication.