<prompt> Patch test is read after:2 hrs2 days2 wks2 months  <response>: Patches are commonly applied on upper back for 48 hrs. Patch test First reading is taken after 48 hrs i.e at 2 days 2nd reading on day 4 i.e 96 hrs Evaluation of patch test reading: Grading Evaluation Clinical findings - Doubt reaction Faint erythema Weak non-vesicular ve reaction Erythema, infiltration, and discrete papules Strong vesicular ve reaction Erythema, infiltration, papules, and vesicles. Extreme bullous ve reaction Intense erythema, infiltration, and coalescing vesicles. 