Find out what causes discolored nails and how to fix and prevent them.
You wear dark nail polish
Red and purple lacquers have pigments that can cause yellowing if they aren't swiped off within two weeks. If you wear these hues, change polish often, or use an acetone-based remover, which is strong enough to take off both the color and the yellow. If you use a nonacetone remover, follow up with a little lemon juice to lighten discoloration. To prevent yellowing in the first place, always apply base coat before polish; it keeps color pigments from reaching and staining the nail surface.
You love to be barefoot
Going shoeless puts you at greater risk for catching a fungal infection; microorganisms outside or inside (say, a locker-room floor) can get into a tiny cut (like a torn cuticle) and work their way under your toenail. Signs of a problem include the nail turning a whitish-yellow color, followed by thickness and crumbling. The last stage: The nail lifts away or comes off completely. If you spot the signs early (when the nail begins to yellow), ask your doctor for a prescription cream.
Your toenails need trimming
If they reach past the tops of your toes, nails' tips can bump against the inside of your shoes. Over time, this damages the nail and, bit by bit, can cause it to detach. Parts that have disconnected will look opaque and pale yellow; you may even notice a blackish bruise (caused by broken blood vessels underneath the nail). If this kind of damage continues, the nail will fall off (or, in some cases, should be removed by a podiatrist or a dermatologist). To prevent toenail trauma, trim nails regularly and choose footwear that allows you wiggle room.