A tuberculosis (TB) skin test, also known as a Mantoux test, is a simple and common procedure used to check for TB infection. The test involves injecting a small amount of tuberculin, a purified protein derivative (PPD) from the TB bacteria, into the skin of the forearm. The test is typically read 48 to 72 hours later by a healthcare professional.
A positive TB skin test indicates that the person has been infected with TB bacteria at some point in their life. However, a positive test does not necessarily mean that the person has active TB disease. Further testing, such as a chest X-ray or sputum culture, may be necessary to determine if the person has active TB disease.