Is it normal to have redness and swelling after receiving the PPD shot?
Apr 07, 2023
Source: Cainiu Health
Dr. Liu Aihua
Introduction
Redness and swelling after receiving the PPD injection are generally normal drug reactions, but could also be due to an allergic response; specific circumstances require medical evaluation at a hospital. If a hospital visit is needed, fasting is usually not required, but it's best to avoid applying cosmetics, as they may affect test results. Additionally, maintain a light diet and avoid spicy or other irritating foods.
In general, redness and swelling after receiving a PPD injection are usually normal drug reactions, but could also indicate an abnormal response due to allergy. Specific conditions should be evaluated at a hospital. The details are as follows:
1. Normal
After receiving the PPD skin test, reactions should be observed within 72 hours. If redness or induration occurs, the size of the induration determines the result. A nodule with a diameter less than 5 mm indicates a negative reaction, meaning no prior infection with *Mycobacterium tuberculosis*. A nodule larger than 5 mm indicates a positive reaction, suggesting previous exposure to *Mycobacterium tuberculosis*.
2. Abnormal
If redness and swelling are severe, it may be caused by an allergic constitution. In serious cases, symptoms such as itching or difficulty breathing may occur. It is important to inform the doctor promptly and take appropriate measures. Avoid scratching the area and minimize contact with irritants such as soap in the short term.
Additionally, when going to the hospital for evaluation, fasting is generally not required. Avoid using cosmetics that might affect test results. Also maintain a light diet and avoid spicy or irritating foods.
