What do negative results in a patch test indicate?

Negative results in a patch test typically indicate that there are no signs of redness or irritation at the test site. This means that the product or substance applied during the test has not caused any adverse reaction, suggesting that the person is likely not allergic to it. The absence of redness or irritation is a clear indicator that the skin has tolerated the material, which is essential information for making informed decisions about product usage, particularly in a barbering context where various products are applied to the skin. This result helps in ensuring customer safety and satisfaction by minimizing the risk of allergic reactions and skin irritations.