I recently purchased a sleeveless white dress that I am hoping to wear often this summer. However, I am concerned that every time I get a little sweaty while wearing it (and there is no way to avoid sweating in the DC summers), it will begin to stain the dress, and eventually I will end up with yellow discoloration at the underarms of the dress.

Does anyone know how to best prevent this? Would something like Scotchguard work? Any other ideas?