MS: DIY Underarm Stain Remover: 1 part Dawn (or any dishwashing liquid, I assume), 2 parts hydrogen peroxide, then add baking soda to create a paste. Use brush to work it in, and let it sit for 1 hour.
7 Tips to get rid of sweat stains from armpit, collar and cuffs
How to rid and prevent underarm stains. Crush 8 – 10 Aspirin pills in a small bowl. Add just enough water to make a paste. Work the paste into the stain. Let it sit on the stain overnight. Wash as you regularly do.
The armpit stain removal trick requires mixing just one part dishwashing liquid with two parts hydrogen peroxide, then let the mixture sit on the stain for an hour. For the worst kinds of stains, add baking soda and scrub.
#StyleHack: How to Remove Yellow Armpit Stains for Good
How To Remove Yellow Armpit Stains. If you suffer from hyperhidrosis (excessive sweating) in your underarms, you can also try miraDry is a solution that offers a permanent reduction in the amount of underarm sweat.
How To Get Rid of Yellow Armpit Stains--- 1 tsp dawn, tsp hydrogen peroxide, TB of baking soda. Mix together. Use small laundry brush and scrub it in. Let it stand for approx 1 hour and then launder as usual. ( instructions copied from this pin)