Skin reaction is a method for determining induced sensitivity (allergy) by applying an antigen (allergen) to, or inoculating it into, the skin; induced sensitivity (allergy) to the specific antigen is indicated by an inflammatory reaction of one of two general kinds: 1) immediate, appears in minutes to an hour or so and in general is dependent upon circulating immunoglobulins (antibodies); 2) delayed, appears in 12 to 48 hours and is not dependent upon these soluble substances but upon cellular response and infiltration.

The simple word for reaction is प्रतिक्रिया, no doubt. But if we elaborate the word, then we find the 'reaction' here is always adverse reaction.