Nail Discoloration Can Be a Mystery. Dermatologists Are Here to Solve It.

NAIL DISCOLORATION AND yellowing isn’t exactly the easiest thing to talk about—and, turns out, pinpointing the cause of it isn’t any easier. With a fairly wide range of visual cues to consider, board-certified dermatologist Dana Stern, MD, explains that ‘discoloration’ is a descriptive catch-all for a nail that has “some kind of color variation from what is considered the normal nail appearance. It’s associated with many different nail issues.”That makes it particularly difficult to treat. After all, you’ve got to know what’s behind your issue before you can tackle it appropriately. What we can tell you for sure: Whether you’re currently experiencing some unwanted color in your nails or are just curious about future indicators, Dr. Stern says that nail discoloration is an under-discussed topic.Meet the experts: Dana Stern, MD, is a board-certified dermatologist in New York City. Jennifer Hanway is a board-certified holistic nutritionist.Well, no longer. Ahead, we break down the specifics on nail discoloration, how to treat and prevent it, and a recently discovered connection between nail discoloration and GLP-1 use.The specifics on nail discoloration.The spectrum of colors that fall under the umbrella term of nail discoloration are plentiful. “It could be a wide variety of colors including brown, black, white, green, red, purple, and yellow,” says Dr. Stern. Below are common associations with each discoloration shade.Yellow: Yellow discoloration of the nails are one of the more common types of discoloration on the list. Shades of yellow can be caused by a fungal infection, which is sometimes accompanied by brown discoloration and brittleness of nails, the effects of nail polish wear due to leaking of the pigment, staining from smoking, as well as the effects of aging, which can dull the nails over time, causing them to develop a yellowish hue. Brown: A brownish hue generally means there is pigment that has been deposited into the nail plate. It can appear because of trauma (i.e. something hitting or falling on the nail), certain medicines, bacterial or fungal infections, skin cancer that developed under the nail, or a stain due to contact with tanning cream or spices such as turmeric. Black: This pigment is usually from blood or a bruise, but it can also be from dirt or debris under the nail. It also commonly appears as vertical lines in people with darker skin tones, and it is completely harmless. It can also be from benign moles that can form in the nail bed. White: White nails are often referred to as leukonychia. “There are many different types of leukonychia. Punctate leukonychia are the white patches within the nail plate often seen in children (not associated with calcium deficiency) while keratin granulations are the superficial white patches often seen on toenails after prolonged polish wear,” says Dr. Stern. Additional white discoloration can be caused by funguses and white lines known as Mee’s lines can follow the contour of the lunula and indicate arsenic poisoning. Onycholysis or nail separation, can also cause the normal white tip of the nail to expand and appear like excessive white at the tip of the nail.Green: Green nails, often referred to as Green Nail Syndrome or ‘greenies,’ are typically an indicator of a bacterial infection from an organism called Pseudomonas aeruginosa. Green discoloration can also appear because of certain dyes or nail polishes, or chemical exposure that tums the nails green.Red: Red color under the nails usually means there is blood or inflammation present. Additionally, reddish half-moons that appear at the base of the nail have been known to be associated with inflammatory diseases such as rheumatoid arthritis. Purple: This is blood in a different stage of healing, fungal infections; a purplish or bluish tint in the nail can occur during times of cold weather and lower oxygen levels in the blood. Blue: Similar to purple discoloration, bluish nails can also indicate a lack of oxygen, cold exposure, or vitamin B12 deficiencies, though it's rare to show in that manner.How often does discoloration happen?The answer: it depends. It’s actually quite common to have discoloration but it’s hard to nail down (pun intended) the rate of occurrence because it’s a symptom of underlying conditions and not considered a disease within itself.Nail changes and discoloration frequently occur due to age, normal changes in growth rate, and yellowing are extremely common in older adults. Fungal and bacterial infections, causing greenish nails make up a large percentage of nail discoloration or abnormalities.Despite overall prevalence and with no single culprit at times, it’s important to understand that nail discoloration can be an indicator of your overall health. “Your nails can reflect aspects of your nutritional status, but they don’t tell you exactly what you’re missing,” explains Jennifer Hanway, a board-certified holistic nutritionist. Though she says that certain changes in nail color have been associated with specific deficiencies, “none is diagnostic on its own,” making it difficult at times to pinpoint the cause and treat it. Dr. Stern mirrors that sentiment, saying that since there is such a wide variety of scenarios for discoloration, it’s important to see a dermatologist.Hanway says that in some cases, vitamin and mineral deficiencies can cause discoloration. “Vitamin B12 can sometimes cause nail pigmentation; iron-deficiency anemia can cause pale nail beds, and in some cases, a condition known as koilonychia, which is when the nail becomes centrally concave.” Other deficiencies, such as zinc, can affect overall nail growth and appearance.What you should do.Though your first step should be to speak to your doctor, it’s also important to take clear photos of your nails for reference and to keep notes. Make reference to which nails are affected, when the changes started, and whether you recently changed your diet, lost weight, started taking supplements, or have begun a new medication. “Speak to your doctor about whether testing for nutritional deficiencies or other factors may be appropriate,” says Hanway.Depending on your symptoms, medical history, and diet, Hanway says that you may need full bloodwork to test for ferritin, vitamin B12, or other targeted tests.How to prevent nail discoloration.Dr. Stern says that you can prevent white patches or keratin granulations by using a base coat when you have your nails done or by avoiding prolonged polish wear. If you’re someone who has their nails done regularly, Dr. Stern recommends seeing an experienced nail tech to avoid any chance of encountering discoloration. “Pseudomonas tend to occur in moist spaces on the nail, classically in a lifted acrylic or other type of enhancement, which is why having them done by a professional nail tech can lessen the chances of this occurring.If you hurt a fingernail where significant blood accumulates under the nail, your dermatologist can evacuate the blood by drilling a small hole in the nail can help to remove the pigment, while also helping to save the nail from falling off.In terms of nutrition, Hanway says that adequate protein and overall nutrient intake matter. “Nails are made primarily of keratin, a structural protein, so getting enough dietary protein supports overall nail health.” Protein options include eggs, fish, greek yogurt, and nutrient dense foods such as red meat, shellfish, which provide you with iron and zinc. “Supplements should be targeted rather than taken on a hunch, and should ideally be with your healthcare professional’s guidance,” she says.A multivitamin may help to fill the nutritional gaps when food intake is limited, but it won’t exactly replace a balanced diet or guarantee any nail changes won’t occur. Hanway cautions against taking biotin supplements, even though they are often marketed for stronger nails. “The evidence of benefit in people without a deficiency is limited,” she says. Higher doses of biotin can also interfere with certain laboratory tests, potentially producing misleading results, so be sure to let your healthcare professional know if you are taking it before having bloodwork.Then, there’s the GLP-1 factor.If you’re one of the millions of American women on a GLP-1 medication, know that a recent study suggests there’s a relationship between nail discoloration and these drugs (although it’s not entirely clear on the connection or causality). The 2026 European Academy of Dermatology and Venereology study reported that nail discoloration occurred in 46 percent of GLP-1 users, compared with 17 percent of adults with obesity or type 2 diabetes who had never taken these medications. To add insult to discoloration, nail detachment was also reported by 39 percent of GLP-1 users, compared with 9 percent of the comparison group. Though these are noticeable differences, it’s safe to conclude that there may be an association, but it does not prove that the medication caused these changes.Dr. Stern points out that the full study was not released to the public, and did not report that about half of the GLP-1 users had nail problems prior to treatment. “This would mean that this study population had a high rate of nail disorders prior to treatment and therefore these nail issues were unrelated to GLP-1 therapy,” she explains. “When the investigators looked at nail changes that began after starting GLP-1, the previously reported associations disappeared entirely. This is a situation where it does not seem that association is equal to causation, but it would be great to have access to the whole study.” Until then, these findings should be considered preliminarily until fully evaluated through peer review.Taryn Brooke is a New York City–based freelance writer, beauty expert, content creator, and filmmaker specializing in beauty, aesthetics, and culture. Her work has appeared in New York, Allure, Glamour, InStyle, Cosmopolitan, New Beauty, and Marie Claire, where she regularly covers skincare, plastic surgery, cosmetic treatments, and makeup trends.Alongside her editorial career, Taryn writes, directs, and produces narrative short films that have screened at film festivals nationwide, including Academy Award–qualifying festivals. Her work across both media and film is driven by a sharp eye for storytelling, visual culture, and the evolving relationship between beauty and identity.Brian Underwood is beauty director at Women’s Health, where he oversees content strategy for the brand across all platforms, including digital, print, and social. Underwood previously served as beauty and wellness director at Oprah Daily and O, The Oprah Magazine. During his tenure leading beauty content for the Oprah brand at Hearst, stories Underwood commissioned were awarded the Skin Cancer Foundation Media Award and a Fragrance Award for Editorial Excellence (his second). He was the launch Beauty Director of Dr. Oz THE GOOD LIFE, and has held additional editorial positions at Fitness, Organic Style, Good Housekeeping, Life & Style Weekly, and Woman’s Day and has written for Self, Shape, Seventeen, Redbook, Cosmopolitan, and many more. Underwood previously served on the Skin Cancer Foundation’s gala committee and as partnerships director of the Trans Beauty Clinic, a New York-based charitable organization that provided beauty services and workshops to the city’s trans community.