Discoloration of toe nails (nails turning yellow-green in color) is a clear indication of toe fungus and is certainly most undesirable. Fungal infection develops through any crack or fissures beneath the nail surface and spreads rapidly discoloring the nails. The sufferer experience pain no doubt and social embarrassment as well. Nails emit a typical odor and become brittle. The infected toe nails need continuous monitoring to check the infection. Toenail fungus is best treated at home to prevent any side effects of over the counter medication. You may need to clip your damaged nails frequently and see that fresh nail growth remains unaffected.