What the risks are:

The risk of severe side effects is very low. Typical reactions include itching and hives. Sometimes, the area may blister. Rarely, the area of swelling may become very large.

Tell your health care provider if you have any severe reactions.

Special considerations:

The test results may be incorrect (false negative). False negative means the test suggests you haven't been exposed to tuberculosis, but you really have been. Incorrect results are more common with this test than with the tuberculin skin test.

This is more likely in the elderly and in patients with weakened immune systems, such as:

• AIDS patients
• Cancer patients who receive chemotherapy
• Those who receive organ transplants
• Anyone taking high doses of steroids