Id Reaction
Id reaction, also known as “auto-eczematization”, is an itchy, eczema-like rash that is a type of acute dermatitis. It typically shows up in a generalized distribution, meaning it is seen not just in one specific area of the body but rather is develops all over the trunk, arms & legs, and sometimes the head and face.
What causes Id reactions?
Id reactions typically develop days to weeks after some other inflammatory skin condition (like an allergic contact dermatitis or an infection) at another site on the skin. Id reactions are often described as an “inflammatory overdrive” or an “inflammatory storm that feeds itself.”
This is a systemic response to some other condition that kickstarted it (like an allergic reaction or infection). Doctors still argue over its exact cause but most feel it is due to cell markers in the blood stream that “signal” the body to increase inflammation all over and its signs are seen almost anywhere on the skin.
What does it look like?
The rash can look different from one person to another – like skin-colored, pink or dark bumps or small blisters or can even look like dark or red, mottling and scaling patches of skin. It is typically quite itchy and most people are uncomfortable. Many people present having lost sleep or having open scratches on the skin from their nails. The rash can be scattered on face, trunk and/or limbs but may show up in some people just on the trunk.
The classic example is “a very itchy rash developing all across the body, arms and legs 2-3 days after a man got athlete’s foot.”
*An important point – this does NOT mean that his infection has spread to other areas where the Id reaction is located. The infection is still localized on the feet but the response to it is seen all over. So treatment towards the infection should still focus on the feet.
How is it treated?
To adequately treat this condition, your dermatologist will have to address the underlying cause of what started it as well as “calm down” the inflammatory storm. This is typically done with oral or intramuscular steroids which work as powerful anti-inflammatory agents. Some people who have a mild rash may be able to use topical steroid creams or lotions alone but anti-inflammatory treatment is still the focus.
What happens if this is not treated?
Because this turns into an inflammatory storm that “feeds itself,” the rash can continue to worsen. I have seen several cases in my career where people are not treated adequately over months and they are miserable with a rash head-to-toe! This certainly should never be the case for anyone but unfortunately, it happens.
Seeing a board-certified dermatologist early in your treatment will keep you from missing out on the correct treatment needed and quickly get you the relief you deserve.