Although, swiping on with abandon may raise some questions: Is it OK to reapply multiple times per day? Is there such a thing as too much deodorant? How can you make sure your deodorant, uh, works? We asked derms for their summertime advice. To be clear: You can face irritation from both traditional and natural deodorant options; although, traditional sticks may include more alcohols and formaldehyde-releasing preservatives, which are common irritants. “While any ingredient can irritate the skin, the fewer ingredients someone is exposed to, the less risk there is of an allergic reaction,” board-certified dermatologist Lisa Airan, M.D., once told mbg. “Traditional deodorants contain more ingredients, which puts the patient at increased risk for skin irritation.” Even if you discover a natural deodorant you adore, though, a couple of ingredients can still aggravate sensitive armpits: First, “Many natural deodorants rely on baking soda to absorb moisture and neutralize odor, but too much baking soda can cause skin irritation in some people,” notes board-certified dermatologist Hadley King, M.D., (baking soda has a basic pH, while your armpits are more acidic; combining them together can cause a reaction). Acid-based formulas (like glycolic-acid-based solutions) are common culprits as well: These effectively lower your skin’s pH and make it too acidic for odor-causing bacteria to thrive1, but some people may find AHAs way too harsh for their liking, especially when relying on multiple swipes throughout the day. That being said, you can go ahead and reapply your deo to your heart’s content—just make sure to limit the frequency (or swap to a gentler product) if you notice any skin irritation. Alas, an exception: If you use crystal deodorant (which contains mineral salts like potassium alum that have antimicrobial properties), you want to apply them on clean, slightly damp skin. “Ideally right after a bath or shower,” says King. Or if you’re reapplying on the go, she recommends wetting the top of the crystal before swiping. That way, the crystal will impart a film on your skin when you apply.
