Soak stained areas in white vinegar or lemon juice

Pour undiluted white vinegar or fresh lemon juice directly onto the yellowed underarm areas, gently work it into the fabric, and let it sit for at least 30 minutes before laundering normally.

Why It Works

The acetic acid in vinegar (typically 5% concentration) and citric acid in lemon juice dissolve the aluminum salt and protein deposits that cause yellowing. These natural acids break down the mineral-organic complex without damaging most fabrics. Both acids also have mild deodorizing properties that help remove lingering sweat odor.

Tips

• For stubborn stains, soak the whole shirt in a basin with 1-2 cups of white vinegar mixed into warm water for 1-2 hours
• Lemon juice works best on white fabrics since its mild bleaching effect can lighten colors
• Check the stain before machine drying — heat will set any remaining discoloration
• White vinegar is the better choice for colored shirts since it will not affect dyes