Aluminum Sulfate

Salt of aluminum

Used as a food additive and medical anticoagulant

Frequently used in deodorant as an absorbent

Also an astringent

Can cause skin sensitivity

Aluminum sulfate is a salt of aluminum. It has numerous commercial and retail applications, including as a food additive and anticoagulant in medical settings. It is also used in water treatment to coagulate (change a fluid to a semi-solid or solid state) impurities so they can be filtered out.

In cosmetics, aluminum sulfate is known for its absorbent and astringent properties and is a frequent additive in deodorants. It can create a tingling or cooling sensation when applied to skin. Though aluminum sulfate is deemed Generally Recognized as Safe (GRAS) by the United States FDA, it can cause skin irritation, especially in those sensitive to aluminum. Note that this side effect can be more pronounced when applied via deodorant to just-shaved underarms.

In its raw form, aluminum sulfate is a white crystalline solid. Amounts between 15–25% are standard when this ingredient is used in deodorants. Other cosmetics typically contain less than 1% aluminum sulfate.

Interestingly, clinical studies of persons with known allergies to dust mites, pet dander and more showed that topical use of aluminum sulfate blunted the allergen’s impact on skin.