Is a 20 cm local reaction to insect sting exaggerated? and what harm can it cause if left untreated?is this person considered atopic?

Insect bite: 20 cm local reaction is an exaggerated local reaction. It most likely represents an allergic reaction to an insect bite. Need to make sure it is not cellulitis which is a secondary bacterial infection. Insect bite reactions usually resolves itself. Using oral Benadryl/ avoid itching/ applying ice helps it get better quicker. If an infection needs to be treated.

See below.: This is a large local reaction. If there is no difficulty breathing or swallowing and no hives, it is not dangerous, but is probably quite uncomfortable. It also depends on the location of the sting. This would not label the person as atopic. I would still recommend seeing your physician if the reaction increases or doesn't decrease. An antihistamine is usually used to treat local reactions.