Have you ever noticed a yellowish stain on your nails after removing your polish? It's definitely a little unsightly and just makes you want to put more polish on to cover it up. Here's how to prevent it. The most likely reason is a color reaction. Darker-colored polishes in particular can stain nails due to a chemical reaction between the colorant and the nail plate. This reaction is hard to predict because it doesn't happen for everybody and for every dark polish. It can also take a few days to a few weeks to occur. It's possible that formaldehyde (a common polish ingredient) is causing the problem. This chemical can react with the keratin protein in your nails and make it brittle and yellow. While rare, nails that are very yellow could be an indication of a nail infection. How do you prevent this?
Don't try to scrape off the stained area because it will damage and weaken the nail.
Stick to lighter colored polish (dark colors are more likely to stain).
Wear a base coat to protect your nails from staining.
Look for nail polishes that don't have formaldehyde on the ingredient list. (There's no guarantee that this will work but it's worth a shot especially if you get yellowing from lighter colored polishes)
Stop wearing polish and wait for your nails to grow out (this can take a while though).
Don't leave dark polish on for a excessive time period, I personally have found that staining gets worse over time.
While not a problem for everyone, those of us do have some options. Take care of your nails by choosing the proper shade, wearing a protective base coat and removing polish regularly. If the problem persists you may want to check with your doctor.