Apply antiperspirant at bedtime, on dry skin
Dermatologists commonly recommend putting antiperspirant on before bed rather than immediately after a morning shower. The key is not the clock itself but the conditions: skin should be completely dry, and sweat glands are generally less active while you sleep. That gives the product time to work before heat and activity increase sweating the next day.
How it reduces sweating
Most antiperspirants use aluminum-based ingredients. They react with moisture in the sweat ducts to form temporary plugs near the skin’s surface, reducing how much sweat reaches it. Leaving the product in place overnight gives those plugs time to form. Applying it to damp skin can make it less effective and may increase irritation.
A morning shower usually does not undo the effect, because the product has already had time to act. Deodorant is different: it mainly helps control odor rather than reducing sweat, so its timing does not work in quite the same way. If a product irritates your skin, stop using it and follow its label; applying it less often or choosing a different formula may help.
