Sweat can leave an unsightly yellow stain on clothing, particularly in the underarm area. Prevention is the best line of defense against these stains, but once the discoloration is there it is still usually possible to remove or minimize it. The best way to remove sweat stains is to catch them while they are new. Older stains are generally much harder to remove. There are a number of products and home remedies that should be able to help get rid of perspiration stains.
Sometimes very mild yellowing can be removed by washing and hanging the clothing in the sun, if the garment is white. Chlorine bleach should probably be avoided since it can actually make sweat stains darker. A detergent with color-safe bleach may work well for colored clothing. Spot-treating the stains with the detergent and pre-soaking may also help. Both colorfast and white clothing may come clean after soaking in a solution that contains an enzymatic cleaner. Several products are available today that use enzymes or oxygen-formulas to effectively remove organic stains like sweat or blood.
Some homemade solutions and pastes may also be effective in removing sweat stains. A paste made from water and baking soda can be applied to white clothing to help remove signs of perspiration. This also helps remove any lingering odor that sweat leaves behind. The paste can be left on for about 20 or 30 minutes before the clothing is laundered. A mixture of about half hydrogen peroxide and half water, with or without baking soda, can also be used to pre-soak white clothing for 20 to 30 minutes before washing.
If underarm stains are new, a product that contains ammonia may help with stain removal. When sweat stains are relatively fresh they contain a high amount of acidity. Ammonia counteracts this and can break down the stain. If the stain is older, the acidity typically fades and it becomes more alkaline in nature. An acidic substance like white vinegar or lemon juice diluted with water can help break down these older sweats stains so they are easier to wash away.
Sweat stain removal does not always work, especially if the stains have been set in by a hot dryer. Prevention can help eliminate the need to try to clean sweat stains after the fact. Choosing a deodorant that does not contain aluminum can sometimes help prevent or minimize yellowing. Wearing an undershirt to absorb sweat before it can soak into outer clothing can also help prevent the problem.