How It Is Done continued...
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.
The major risk with the skin prick test
or the intradermal skin test is a severe allergic reaction called
anaphylaxis. Symptoms of a severe allergic reaction
include itching, wheezing, swelling of the face or entire body, trouble
breathing, and low blood pressure that can lead to
shock. An anaphylactic reaction can be
life-threatening and is a medical emergency. Emergency care is always needed
for an anaphylactic reaction. But severe allergic reaction is rare, especially
with the skin prick test.
If 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.
There is very little risk of a problem
from having blood drawn from a vein.
- You may develop a small bruise at the
puncture site. You can reduce the risk of bruising by keeping pressure on the
site for several minutes after the needle is withdrawn.
- In rare
cases, the vein may become inflamed after the blood sample is taken. This
condition is called phlebitis and is usually treated with a warm compress
applied several times daily.
- Continued bleeding can be a problem
for people with bleeding disorders. Aspirin, warfarin (Coumadin), and other
blood-thinning medicines can also make bleeding more likely. If you have
bleeding or clotting problems, or if you take blood-thinning medicine, tell
your doctor before your blood is drawn.