Definition

• The ID tissue layer is directly under the skin.Image by Flickr.com, courtesy of Josh Pesavento
  
  There are three layers of tissue that are just below the skin. PATH, the global health company, explains the structure of these tissues: "These tissue layers are intradermal, subcutaneous and intramuscular. Subcutaneous and intramuscular are the most common for vaccines."
  
  

Method

• ID vaccinations are inserted perpendiculalry into the skin.Image by Flickr.com, courtesy of Todd Huffman
  
  Vaccinations usually are given in muscle rather than tissue. Science Candy describes how an ID vaccination is done: "The ID method uses a narrow 1.5 mm needle which is inserted perpendicularly into the skin rather than into deeper tissues beneath the skin or muscle."
  
  

Considerations

• There can be side effects from an ID shot or vaccine.Image by Flickr.com, courtesy of Lauren Nelson
  
  There can be side effects from using an intradermal shot or vaccination. Science Candy sites the problem of "increased local inflammation and redness."
  
  

Function

• ID is used with allergy testing.Image by Flickr.com, courtesy of Andrew Kuznetsov
  
  The intradermal technique also is used frequently with people and dogs in testing for allergies. Health Central reports that "intradermal allergy testing is another method of skin testing to help determine whether an individual is allergic to a specific allergen. The allergen is injected under the surface of the skin."
  
  

Advantages

• ID allergy testing offers more consistent resultsImage by Flickr.com, courtesy of psyberartist
  
  There are advantages to using ID in allergy testing. According to Health Central, "The intradermal test is more sensitive than the skin prick test and can usually provide more consistent results."