How long should a patch test be left before assessing for reactions?

A patch test should be left on the skin for 24 to 48 hours to accurately assess for reactions. This timeframe allows for any potential allergic response to develop fully, as reactions may not be immediate. Leaving the test for this duration provides sufficient time for the body to demonstrate sensitivity to the substance being tested. Assessing too soon might miss a reaction, as some skin sensitivities require a longer incubation period to manifest. Therefore, waiting at least 24 hours before checking for reactions ensures a more reliable result. This approach is a key practice in salon procedures and helps maintain client safety by identifying any potential allergic responses to products that may be used during services.