The effectiveness of diphenhydramine in treating type I hypersensitivity reactions is indicated by a reduction or elimination of allergy symptoms such as hives, itching, and swelling after its administration.
An indicator that diphenhydramine is effective in treating a patient's type I hypersensitivity reaction would be a reduction or elimination of the symptoms associated with this allergic response. Type I hypersensitivity reactions involve the release of histamine from mast cells, which leads to allergy symptoms. Diphenhydramine, an antihistamine, works by blocking the action of histamine and can diminish symptoms such as itching, swelling, and hives.
A clinical demonstration of the drug's efficacy could include a decrease in the severity or complete resolution of symptoms such as hives, which are a common manifestation of allergic reactions. For instance, if fewer patients report or exhibit symptoms like hives after taking diphenhydramine compared to a placebo or another medication, this would suggest that diphenhydramine is effective.
So, the reduction or absence of allergy symptoms such as hives, itching, and swelling indicates the effectiveness of diphenhydramine in treating type I hypersensitivity reactions.