Is there a time of day at which antiperspirant should be applied in order to best relieve excessive sweating ?

The answer is YES. An important study published in 2001 shows that there is a daily variation in the pH of skin and that this may influence effectivenes of aluminum chloride solutions for hyperhidrosis (excessive sweating). Skin pH is highest in the morning and falls, meaning that it becomes more acidic as the day goes on. The antiperspirants therefore are more effective when they are applied in the morning when skin pH is higher.

This scientific data is consistent with clinical research done at the Center for Excessive Sweating. Dr. Karamanoukian's study with 236 patients in 2003 showed that there was such a trend although it did not reach clinical significance.