The PPD reading window is firm: 48 to 72 hours after placement. Read too early and a developing reaction may be missed; too late and a true reaction may have faded. If you miss it, the only fix is starting over with a new placement (and new fee). This is exactly why many people choose the one-visit QuantiFERON blood test instead.
What if I miss my TB skin test reading window?
Quick answer:
The test must be read 48–72 hours after placement. Miss the window and the test must be repeated — plan your placement day accordingly.
Choose your TB test
Walk in 6 days a week at 1102 West Kemper Rd., Forest Park — or book online and skip the wait. Most visits under an hour.
