What even do “healthy nails” look like? If you use your hands a ton, you might get a good glimpse at your nails pretty often. You may notice something like a snagged nail when texting and blow it off for future you to worry about (relatable). But it’s worth making sure your nails look healthy to signify that they are healthy.
If you have healthy nails, the tips should be white, and the surface smooth with a subtle shine, Dana Stern, M.D., assistant clinical professor of dermatology at Mount Sinai Medical School, tells SELF. “Nail beds are pink,” she adds. “Cuticles are intact and well moisturized. Hangnails are absent.” When your nails start to look off for reasons beyond having gone a long time without filing them down, or spending a weekend diving into yard work, it can be indicative of an internal health issue.
“There are many issues that present in the nail” as changes in color, shape, and structure, Dr. Stern says. Here are some of the most common nail problems that could have an underlying cause that’s more than skin-deep.
1. Your nails have small dents in the surface.
This phenomenon is called pitting. When pitting shows up with no apparent pattern, it’s typically indicative of psoriasis or psoriatic arthritis, but can also be related to connective tissue disorders like Reiter’s syndrome (a type of arthritis triggered by an infection elsewhere in the body). When pitting shows a regular pattern, it can be a sign of alopecia areata, a type of hair loss caused by an autoimmune response1.
If what you’re noticing isn’t quite pitting but is instead deep lines or grooves in your nails, you might be dealing with a phenomenon known as Beau lines. Some lines on your nail can be normal, but Beau lines are noticeably deep and run width-wise on the nail, not vertically. These can appear after really intense stress to your nail makes it stop growing (or grow more slowly than usual) for some time2. Causes of this can include high fever, which is why there’s been concern about “COVID nails,” or what some experts think may be Beau lines manifesting after COVID-19 infection.
2. Your nails are concave, like spoons.
This is called koilonychia, and it can be a completely normal age-related change to your nails, Dr. Stern says. But it may also indicate iron-deficiency anemia or other disorders where iron is not metabolized correctly, like hemochromatosis and Plummer-Vinson Syndrome, which happens after long-term, chronic iron-deficiency anemia3. “Treating the iron issue can help to normalize the nails,” Dr. Stern says. “Anyone who suddenly develops spoon-shaped nails should have a workup by their physician.”
3. Your nails are white.
When the part of the nail closest to the cuticle is solid white and the distal part (the farthest section that’s still attached to the nail bed) is pink, this is called half-and-half nails. “It’s also referred to as Lindsay’s Nails,” Dr. Stern says. Sometimes the cause of this is unclear, and experts are researching the potential for Lindsay’s Nails to be genetic. But other times, this half-and-half white coloring can be a symptom of a more serious issue like chronic kidney disease4. When two-thirds of the nail is completely white and just a sliver on the end of the nail bed is pink, it’s called Terry’s Nails5. “This can be indicative of cirrhosis, congestive heart failure, or diabetes mellitus,” Dr. Stern says.
4. Your nails have brown or black stripes.
A dark brown or black stripe along your nail, or brown pigments surrounding the nail, will most often just be benign moles or pigmentation. This is most common in people with darker complexions because they tend to have more pigment-producing melanocytes in their skin and nails6. When the melanocytes are stimulated, usually through trauma to the cuticle (aggressive and repetitive cuticle pushing, cutting, picking, or biting), “these cells begin to produce pigment, appearing as a brown, length-wise band in the nail,” Dr. Stern explains.
However, it’s important to know that this can potentially indicate melanoma of the nail. “Melanoma is a type of cancer that most people tend to associate with the skin; however, melanoma can arise in the nail as well,” Dr. Stern says. “The thumb, index finger, and great toenail are the most common digits to have melanoma.”
Since it’s very difficult to distinguish early melanomas from benign pigments, “it is imperative to see a dermatologist for a thorough exam and consultation” if you notice this symptom, Dr. Stern says. This is especially the case if the dark streak is changing in some way, like widening or getting even darker. This is also key to keep in mind if you have dark skin, as you can be more vulnerable to getting melanoma on your hands and feet (which can present on your nails). Nail melanoma tends to be diagnosed late, but if you catch it early, it’s often treatable.
5. Your nails are yellow.
Dr. Stern notes that most commonly, nails turn yellow because of nail polish use. So, that’s a relief! But if you haven’t been painting your nails a lot lately, it could be a very rare issue called yellow nail syndrome7. “With yellow nail syndrome, nails appear thick and have a yellow/green hue,” Dr. Stern explains. “They frequently lack a cuticle as well as a lunula (the half-moon at the base of the nail that is usually visible on the thumb and great toe).”
This syndrome is a sign that the nails weren’t able to grow correctly and is often due to a lung condition called bronchiectasis or lymphatic disease. “Bronchiectasis is a condition in which damage to the airways causes them to widen and become flabby and scarred,” Dr. Stern explains. It’s usually the result of a health issue like an infection and can compromise circulation, which affects nail growth. “Because bronchiectasis tends to be chronic, yellow nail syndrome does, too,” Dr. Stern says. Problems with the lymphatic system can impact circulation, preventing “oxygen, nutrients, and blood from getting to extremities,” Dr. Stern explains, and sometimes causing yellow nail syndrome.
6. Your nails are growing with a downward curve.
If your nails are curving down and have a noticeable rounded edge—kind of like upside down spoons—this could be a sign of clubbing8. Clubbing can even make the tips of your fingers appear swollen or bulging. Clubbing is typically caused by a lack of oxygen in the blood, so it can happen with many different heart or lung diseases. Lung cancer is the most common cause, but congenital heart problems or infections of the heart or lung can also give nails this clubbed appearance. It may also be a sign of IBD or another inflammatory problem in the GI tract, like celiac disease.
7. Your nails are separating from their nail beds.
This condition, called onycholysis, is typically painless and is usually more likely to happen if you’ve got longer nails. The most common cause is simply trauma to the nail. But it is also associated with psoriasis9. If separation happens suddenly and in many nails, it can be a sign of hyperthyroidism, Dr. Stern notes.