Treat the spot as soon as possible:

The quicker you act, the better your chances of success in removing sweat patches. Try to tackle the spot as soon as possible, preferably right after you take off the shirt.

Use white vinegar:

White vinegar is a great remedy to treat sweat patches. Mix equal parts white vinegar and water and gently apply this mixture to the sweat patches. Let it soak in for a while, but make sure the vinegar doesn't stay on the fabric for too long. Then wash the shirt as you normally would.

Baking soda and water paste:

Baking soda is known for its absorbent and odour-neutralising properties. Make a paste of baking soda and water and apply it to the sweat spots. Let it soak in for some time before washing the shirt.

Lemon juice:

Lemon juice is known to remove stains and neutralise unpleasant odours. Dab some fresh lemon juice on the sweat spots and let it dry in the sun for a while before washing the shirt.

Use aspirin:

Aspirin contains salicylic acid, which can help remove sweat patches. Crush a few aspirin tablets and mix them with water to make a paste. Apply this mixture to the spots, leave it on for a while and then wash the shirt.

Special stain removers:

There are also commercial stain removers available that are specially designed to tackle sweat patches. Follow the instructions on the packaging and test the product on an inconspicuous area first to avoid possible damage to the fabric.