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.
TESTED: The BEST Way to Remove Yellow Sweat Stains
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)
Goodbye to Yellow Armpit Stains: one part Dawn dishwashing liquid + two parts hydrogen peroxide + some baking soda. Use a small laundry brush to work the mixture into the stain for a few minutes. Let sit for an hour or so then launder as usual.
One part Dawn dishwashing liquid mixed with two parts HYDROGEN PEROXIDE. Add baking soda for scrubbing help. Use laundry brush to work into the stain. Supposed to actually take yellow armpit stains out of white shirts!
Tipsy Tuesday: How to get pit stains out of shirts