How It Is Done continued...
If the skin
prick test is negative, you may choose to have an intradermal skin test at a
later visit. A skin prick test is usually done first because the intradermal
test has a greater chance of causing a severe allergic reaction.
The skin prick test and the intradermal test usually take less than an
A skin patch test also uses
small doses of the suspected allergen. For this test:
- Doses of allergens are placed on patches that
look like adhesive bandages.
- The patches are then placed on the
skin (usually on your back). This usually takes about 40 minutes, depending on
how many patches are applied.
- You will wear the patches for 24 to 72 hours.
Do not take a bath or shower or do any activities that could make you sweat
excessively while you are wearing the patches. This could loosen the patches
and cause them to fall off.
- The patches will be removed by your
health professional, and your skin will be checked for signs of an allergic
The health professional drawing your
- Wrap an elastic band around your upper arm to stop the flow of
blood. This makes the veins below the band larger so it is easier to put a
needle into the vein.
- Clean the needle site with
- Put the needle into the vein. More than one needle stick
may be needed.
- Attach a tube to the needle to fill it with
- Remove the band from your arm when enough blood is
- Apply a gauze pad or cotton ball over the needle site as
the needle is removed.
- Apply pressure to the site and then a
The blood sample will be placed on specially treated
paper and sent to a lab to determine whether
antibodies to any of the allergens being tested are
present. If specific antibodies are found, it may mean you are allergic to a
How It Feels
With the skin prick test and the
intradermal skin test, you may feel a slight pricking sensation when the skin
beneath each sample is pricked or when the needle penetrates your skin.
If you have an allergic reaction from any of the skin tests, you may have
some itching, tenderness, and swelling where the allergen solutions were placed
on the skin. After the testing is done, cool cloths or a nonprescription
steroid cream can be used to relieve the itching and swelling.
you are having a skin patch test and you have severe itching or pain under any
of the patches, remove the patches and call your doctor.
You may feel nothing at all from the
needle puncture, or you may feel a brief sting or pinch as the needle goes
through the skin. Some people feel a stinging pain while the needle is in the
vein. But many people do not feel any pain or have only minor discomfort after
the needle is positioned in the vein.