If your armpits stay steamy as a sauna despite your use of over-the-counter antiperspirants, you may need to switch to a prescription-strength alternative. People bothered by excessive sweating often find relief by using an antiperspirant that contains stronger concentrations of aluminum chloride hexahydrate. Over-the-counter antiperspirants typically contain 10 to 25 percent of this active ingredient, while prescription antiperspirants contain 30 to 45 percent aluminum chloride.
As the aluminum chloride-laced antiperspirant is applied to underarm skin, it actually relies on sweat to work properly. Any perspiration, no matter how slight, helps break down the antiperspirant layer into particles small enough to be absorbed into sweat ducts. The aluminum chloride plugs the ducts temporarily, slowing the formation and flow of sweat [source: International Hyperhidrosis Society].
But did you know there's a certain time of day that makes antiperspirant application more effective?