Rinse the stained area with cold water as soon as possible
Mix equal parts white vinegar and water
Apply the mixture to the stain and let it sit for 15 to 30 minutes
Gently rub the fabric together or use a soft brush
Sprinkle baking soda on the stain for extra cleaning power
Make a paste with baking soda and water and apply it to the stain
Let the paste sit for 30 minutes
Wash the shirt with laundry detergent in the warmest water safe for the fabric
Add an oxygen-based stain remover if the stain remains
Avoid using chlorine bleach on white shirts with sweat stains, especially if they contain protein-based residue
Air-dry the shirt and check the stain before using a dryer
Repeat the treatment if needed before drying
For yellow underarm stains, use hydrogen peroxide, baking soda, and dish soap mixed into a paste
Test any cleaning solution on a hidden area first
Wash shirts promptly after wearing to prevent stains from setting