The skin under the arms is delicate, even if it is a powerhouse of sweat production. Unfortunately, antiperspirants are known for causing skin irritation, especially those that contain higher levels of aluminum chloride as an active ingredient. To help combat the itching and stinging that some sweat-blockers cause, take a few precautions. Don't apply products to your underarms within one to two days of shaving them, and don't take a hot shower that opens the skin's pores right before applying antiperspirant.
Instead, massage the antiperspirant onto dry, cool underarm skin right before you go to bed. People typically sweat less at night, when they are resting, so it won't get washed away before it has time to be absorbed into your glands. Make sure to leave the antiperspirant on your skin for at least eight hours; it works more effectively that way, and its effectiveness will build if you follow your nighttime antiperspirant application by a second application the next morning [source: International Hyperhidrosis Society].
Of course, even the strongest antiperspirant won't do much good if your skin is covered with heat- and moisture-trapping fabric all day. Find out which fabrics keep your skin cool on the next page.