Combine one part Dawn dish soap with two parts hydrogen peroxide. Add enough baking soda to make a paste. Rub it into the perspiration stain and let it sit for an hour before washing.
How to Get Rid of Yellow Underarm Stains in 20 Seconds Flat
How to remove underarm stains from your shirt with salt: Dissolve the salt in the hot water, and use a towel to scoop up the solution and rub it into the underarm area. As with the other tricks, wait for the solution to dry before seeing results.