Our bodies try to maintain a constant temperature of 98.6 degrees Fahrenheit (37 degrees Celsius), and when the heat is on (whether from a hot day, exercise or stress) they turn up sweat production to cool us down. On average, we produce about 0.5 gallons (just about 2 liters) of sweat a day, mostly from our eccrine glands, which are sweat glands located in our skin. When the eccrine glands secrete too much sweat -- more than is needed for regulating body temperature, whatever that volume may be -- it's a condition known as hyperhidrosis.
Hyperhidrosis can be a full-body problem or specific to one (or more) areas of the body, usually the palms of the hands, soles of the feet, face or underarms. An estimated 3 percent of Americans have the condition, and with early diagnosis and treatment, it can be relieved in more than 90 percent of cases. When feet are excessively sweaty it's known as plantar hyperhidrosis, and this type of hyperhidrosis affects roughly 30 percent of people with the condition [source: Haider].
The first-line defense against plantar hyperhidrosis is to try topical treatments: antiperspirants. Antiperspirants work by plugging sweat ducts -- they don't stop sweat, they just reduce the amount that's secreted onto the skin. While over-the-counter antiperspirants may help with mild hyperhidrosis symptoms, most products on the market don't contain high enough concentrations of the active ingredients needed to tackle the problem. Antiperspirants that contain high levels of aluminum-based compounds, such as aluminum chloride and aluminum chloride hexahydrate, are not always effective but do offer many patients some relief. Formulas with concentrations of 20 to 40 percent are typically used for the soles of the feet compared to the 15 to 20 percent concentrations prescribed for other affected areas of the body.
Whether used on your armpits or the soles of your feet, antiperspirants are often most effective when applied to dry skin before going to bed and left on for about 6 to 8 hours. Since skin is constantly regenerating, sweating will return if you stop applying the topical treatment. You'll need to use antiperspirant regularly for consistent results.
Topical treatments aren't free from side effects. Some people using topical aluminum chloride may find it doesn't work for them or that they develop itchy, red skin where they applied treatment. If this happens, see your doctor for further recommendations.