Figure 17-2.

Intradermal skin testing (using a 25G 5/8 needle) to weeds on a young asthmatic male who reported itchy, watery eyes, nasal congestion, and worsening shortness of breath and wheeze in the fall.

After epicutaneous skin testing revealed only minimal sensitivities to trees and grasses, intradermal skin testing (more sensitive) revealed strong cutaneous reactions to multiple weeds. With the patient's history of worsening symptoms in the fall, this testing provided a better explanation for his worsening seasonal symptoms. Although the patient displayed multiple positive intradermal tests, he was clearly not allergic to lamb's quarters (labeled “6”). (Courtesy of Patrick H. Win, MD.)