Dark nail polish and discolored nails dilemma

Dear Alice,

I was wondering what causes fingernails to turn yellow if you leave nail polish on for a long time. Is it bad? And what can you do about it?

Dear Reader,

Many people enjoy a manicure or pedicure as a relatively quick and inexpensive way to create a “look” or help them feel pulled together. As you have noticed, however, some nail polishes can cause nails to turn an undesirable yellow. The short answer is that in the case of nail polish and nail plate staining, the color painted on your nail can actually penetrate the layers of the keratin of the nail itself. This leads to discoloration and usually appears yellow. And it’s not just polish that can do a number on your nails — other cosmetic products are common culprits as well. Although the causes for the yellowing and the loss of the nail are slightly different, the recommendations for discoloration remediation are similar. You'll be happy to know that time is on your side; taking a break (even for just a few weeks) will likely help resolve most nail discoloration issues.

Reader, you ask about whether leaving polish on for a “long time” will result in discoloration. Nails can become stained by polish when left on for a brief a period as one week. And though polishes come in all colors of the rainbow, research reveals that most commonly, D&C Red No. 6, 7, 34, or 5 Lake are the dyes that lead to nail discoloration. The good news is that once the polish has been removed, most of the time it only takes another two weeks for the discoloration to fade.

If you’re concerned about avoiding nail discoloration, it’s also worth mentioning that some other treatments might turn your nails an unwanted hue. Products called “nail hardeners” contain formalin, dimethyl urea or glyoxal: these three chemicals often have a nail hardening effect, but they also prevent the nail from being as flexible as it normally is, potentially creating a brittle and slightly yellowed nail. Cosmetic, sculptured, or prosthetic nails can also lead to discoloration of the natural nail underneath (as well as separation of the nail from the nail bed, called oncholysis).

The takeaway here is that while you needn’t avoid primping and polishing, nails just need a break sometimes. Here are a few tips on keeping your nails the color you want during cosmetic treatment:

  • Dermatologists recommend shedding the polish for about 14 days to rid your nails any staining associated with nail polish. If your nails are still stained after that — there’s no need to fret. Your nails will typically grow out of it. Just let them go polish-free for a couple of months.
  • If you use a nail hardener, try rotating it out with a non-nail hardening basecoat either weekly or every other week.
  • Taking a one month break when wearing nail prosthetics can help your nails return to their natural state and keep them healthy. It’s not recommended to wear them longer than three months continuously.

Though discolored nails can easily result from polish use and cosmetic treatment, in certain cases, discolored nails can be an indication of more serious issues. For example, chemotherapy, arthritis medications, psoriasis, lung disease, and continued exposure to paints, rust, and fungus may cause yellowed nails. In addition, nail discoloration is commonly caused by nicotine use. If you’re concerned that your yellow nails may have been caused by any of these conditions, making an appointment with your health care provider or a dermatologist might be helpful to figure out what to do next.

Hope this helps keep your nails happy!

Last updated Feb 27, 2015
Originally published Dec 04, 1998