1. Wash light-colored underwear with hydrogen peroxide

1. Pour hydrogen peroxide into a small bowl. Hydrogen peroxide, a common household disinfectant, is also very effective at removing stains. If the panties stained with menstrual blood are light-colored or white, pour 120 ml of hydrogen peroxide into a small bowl. This will make it easier to use the hydrogen peroxide you need, and you won't have to worry about menstrual blood getting on or in your hydrogen peroxide bottle.
Hydrogen peroxide will bleach fabrics and should not be used on dark or bright underwear.
Hydrogen peroxide is most effective on fresh blood and may also remove clotted blood.
2. Dip the corner of a rag or sponge in hydrogen peroxide. Take a rag, sponge, or stack of paper towels and dip a corner into the hydrogen peroxide. Dip only one corner into hydrogen peroxide for more precise rubbing onto the bloodstain.
Use a rag or sponge that you don't mind getting dirty, as they will absorb some of the menstrual blood afterwards.
3. Gently wipe the blood stain from the outside in. Press the corner of the rag that has absorbed hydrogen peroxide directly on the blood stain to absorb blood from the periphery to the center. If necessary, pour more hydrogen peroxide on the rag to thoroughly soak up the blood. You can even pour more hydrogen peroxide into the bowl if necessary.
When this corner of the rag has absorbed the menstrual blood, switch to a clean corner to continue washing the menstrual blood.
4. Rinse with cold water and repeat the above steps until all blood is sucked away. Once most of the blood has been sucked away, turn on the faucet, rinse the panties under cold water, and inspect the fabric. If there is still blood, keep repeating the above steps to suck it away until all the blood is gone.
If the menstrual blood has coagulated, there may be a small amount of blood that is difficult to remove after washing. In this case, an enzymatic cleaner is recommended to remove the last remaining blood stains.

Once the blood is completely gone, let the panties dry naturally or place in the dryer.

Two, wash dark underwear with salt
1. Mix salt with a small amount of cold water to make a scrub. The exact amount of salt depends on the size and severity of the blood stain. You may want to start with 75 grams and add about 1 teaspoon (5 ml) of cold water, or just enough to make salt cubes, and mix them well.
Salt does not cause discoloration of underwear, so it is suitable for dark or brightly colored underwear.
Salt scrubs are most effective on fresh blood stains, but may also be helpful for removing clotted blood stains.
You can pour the ingredients into a bowl and stir, or just pour the salt over the panties and add water.
2. Cover the blood stain with a salt scrub. Apply a generous amount of salt scrub to the blood on your panties. The salt will draw blood out of the fabric, try to cover the entire stain as much as possible.
If the blood has clotted, let the salt sit on the fabric for about 5 minutes before wiping.
3. Use a rag, an old toothbrush, or your finger to wipe the blood stain. After the bloodstains are thoroughly covered with salt, rub the salt into the bloodstains to break them up. Try wiping in a fixed direction, such as from the outside to the inside, or from one end to the other. This way you don't miss bloodstains anywhere.
For example, you can wipe from top to bottom, left to right, or from the periphery to the center of the bloodstain.
4. When done, rinse off the salt with cold water. Remove as much blood as you can, then grab your panties and run the cold water tap to rinse them off. Use your fingers to wipe off the salt left on the panties and check to see if the blood is gone.
Hot water can cause any remaining blood to penetrate deeper into the fabric, making it harder or impossible to wash off at all.
Once the blood is gone, hang the panties to dry, or put them in the dryer. If blood stains remain, try other methods to remove them.