[citation needed] The "skin scratch test" as it is called, is not very commonly used due to the increased likelihood of infection.

[citation needed] Some allergies are identified in a few minutes but others may take several days.

A negative test does not conclusively rule out an allergy; occasionally, the concentration needs to be adjusted, or the body fails to elicit a response.

The allergens on the patch include latex, medications, preservatives, hair dyes, fragrances, resins, and various metals.

[9] To prevent a severe allergic reaction, the test is started with a very dilute solution.

After 10 minutes, the injection site is measured to look for growth of wheal, a small swelling of the skin.

If the wheal grows larger than 13 mm, then no further injections are given since this is considered a major reaction.

Physicians who perform skin test always have equipment and medications available in case an anaphylaxis reaction occurs.

The IgE antibody plays a vital role in allergies but its levels in blood do not always correlate with the allergic reaction.