If you suffer from acne, you might have exhausted over-the-counter treatments and don't want to try prescription medications. Acne is common in the teen years and affects around 85 percent of people at some time in their lives, according to the American Academy of Dermatology. You might see potassium alum advertised as an acne treatment, although it's more often suggested as a natural deodorant. Ask your doctor before using potassium alum to treat acne.

Potassium alum is a mineral found in two forms, a rock form, called kalunite, and a fiber form, called kalinite. Potassium alum is approved by the Food and Drug Administration for use in cosmetics and is also used in manufacturing.

This mineral acts as an astringent. Astringents dry the skin. Astringents also have a mild antiseptic effect when applied to your skin. Astringents also remove dead skin cells from your skin's surface. Your skin might feel tight or tingling after applying astringents such as potassium alum, according to Skin-care-tips.org.

If you have very oily skin, an astringent such as potasssium alum might help acne. However, if you do not have excessively oily skin, you should not use astringents because of their harsh effects on your skin, according to the National Institute of Arthritis and Musculoskeletal and Skin Diseases. If you do use astringents such as potassium alum, dab them only on the oily spots. Astringents, although often used as acne treatments, do not have clinically proven benefits, dermatologist Dr. David Leffel of Yale School of Medicine states in his 2000 book, "Total Skin: The Definitive Guide to Whole Skin Care for Life."

Astringents such as potassium alum can dry your skin too much, causing skin to peel and look dry and flaky. If you have sensitive skin, astringents can cause rashes, redness, burning and irritation. Ask your doctor for the most effective type of acne treatment for your skin.