How do you avoid getting yellow deodorant stains on white shirts?

One way to prevent them is switch to an “all natural” deodorant. Many deodorants, especially aerosols, have trace amounts of various metals in them, usually iron. That’s what causing the yellow stains: sweat+fine metals.

For white shirts that are already stained, after you wash them, while they are still wet, spray the affected area with hydrogen peroxide. Then let them hang dry in a very sunny area. When the shirt dries, the stains will be lighter/gone. You can repeat this on dry shirts as well, for tougher stains.

I always thought that plain old sweat rings also left yellow rings. No?

I have found that a paste of baking soda and water works well as a natural deodorant. Just rub it under arms w. fingers.Possibly may work fairly well as an anti-persp. as well; it depends how drippy you get.

Sweat rings do leave a discoloration, but those very pronounced yellow stains specifically found in the underarm are from deodorant. Notice on workout or jogging shirts that are heavily sweat in, that the rest of the shirt that gets heavy sweat (like up the center of the back or directly under the front of the neck) don’t retain those yellow stains.

Don’t wear any!?