Your nails might not be the first place you look to for signs that you’re killing it at this life thing, but surprisingly, you can tell a lot about your health from your nails.
What do healthy nails look like, though? First, “normal” fingernails should have white tips with a smooth finish and subtle shine, Dana Stern, M.D., assistant clinical professor of dermatology at Mount Sinai Medical School, tells SELF. Your nail beds should be flesh-colored, meaning they skew pink, tan, or brownish. “Cuticles are intact and well moisturized,” Dr. Stern adds. “Hangnails are absent.”
If your nail color, shape, or structure starts to look a bit odd for reasons beyond normal wear—say, you spent all weekend deep cleaning the house or you’re really due for a manicure—then it’s possible your fingernail health may indicate a deeper issue with your overall health, Dr. Stern says. Here are the most common nail problems that potentially signal something that’s more than skin-deep, according to dermatologists.
1. You have small dents in the surface of your nail.
Small dents on the surface of your nail bed are called pitting, and when they show up with no apparent pattern or reason, this could indicate an autoimmune disorder, conditions in which the body mistakenly starts attacking healthy cells, leading to inflammation.
For example, pitting is typically connected to psoriasis (a skin condition that causes scaly patches to appear on the skin) and psoriatic arthritis (a type of arthritis that commonly affects people with psoriasis). But the phenomenon 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 response, according to the Mayo Clinic.
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 time, according to the American Academy of Dermatology Association (AAD). 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 in which iron is not metabolized correctly, like hemochromatosis and Plummer-Vinson Syndrome, which happens after long-term, chronic iron-deficiency anemia.1 If your doctor determines you have low iron levels via a blood test, treatment can usually help with the appearance of your nails. “Anyone who suddenly develops spoon-shaped nails should have a workup by their physician,” Dr. Stern says.
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, which Dr. Stern says is also called Lindsay’s nails.
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 disease. 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 nails.2 “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 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 nails.3 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.
But 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 it’s also an instance where you can tell more about your health from your nails and signal that you have a very rare issue called yellow nail syndrome, according to the National Organization for Rare Disorders. “With yellow nail syndrome, nails appear thick and have a yellow to 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 turn blue or green.
Discolored nails that are blue or green can indicate a range of health concerns, depending on the specific color. For example, blue nails could mean you don’t have enough oxygen in your bloodstream, which can happen with numerous medical conditions, such as pneumonia, according to the AAD. But blue nails could also indicate some sort of poisoning. (Typically this occurs with argyria, or silver poisoning, which only happens if you’re chronically exposed to large quantities of silver, like from a manufacturing job or consuming silver.)
Other times, your fingernail may turn green-ish black if you have a bacterial infection under your nail. The medical name for this is paronychia, and it can happen if bacteria gets into a cut near your cuticle and infects the skin under your nail, according to the Cleveland Clinic. The skin surrounding your nail may become inflamed, swollen, and painful. Typically, you’ll need to see a doctor to get an antibacterial medication or else the infection will become worse.
7. 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 a condition called clubbing, according to Mount Sinai. Clubbing can even make the tips of your fingers appear swollen or reddened. Your nail beds might feel soft and it can seem like your nails aren’t firmly attached to the bed.
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 G.I. tract, like celiac disease.
8. Your nails separate from their nail beds.
This condition, called onycholysis, is typically painless and is usually more likely to happen if you have longer nails. The most common cause is simply trauma to the nail, such as too much nail filing or irritation from chemicals used during manicures.
Onycholysis can also be caused by a fungal infection in the nail, and it’s sometimes associated with psoriasis, according to the AAD. If separation happens suddenly and in many nails, it can be a sign of hyperthyroidism (a hormone condition that increases your metabolism), Dr. Stern notes.
There are numerous reasons your nails might separate from their nail beds, so your doctor may not be able to explain why it’s happening to you based on a physical exam alone. So, you may have additional testing, such as a blood panel, to figure out what’s going on.
9. You have ridges in the center of your nail.
If you notice ridging or stripes on the middle of your nails (this sort of looks like a washboard) and you frequently pick at your cuticles, you may have what’s called a habit-tic nail trauma. “When people traumatize their cuticles, they accidentally traumatize the cells in the matrix, and then the nail plate doesn’t grow out smoothly,” Dawn Marie R. Davis, M.D., chair of clinical dermatology at the Mayo Clinic, tells SELF. In turn, your nails will develop this washboard appearance.
Habit-tic nail trauma is related to obsessive compulsive behaviors4 and may indicate that you have a lot of underlying anxiety, like if you pick at your nails when you’re super worried. When Dr. Davis suspects that a patient has this issue, she will ask about their anxiety and stress levels, and if appropriate, refer them to a mental health professional who can help them develop strategies to better cope with these emotions.
10. Your nails become thick, overgrown, curved, and opaque.
This is commonly referred to as “ram’s horn nail,” because your nails can resemble a ram’s horn as they grow out. (Medically, the condition is called onychogryphosis.) Sometimes, people get this condition because it runs in their family or because their nails endure repeated trauma without proper care.5 (For instance, it can affect toenails if you constantly wear tight shoes that put a lot of pressure on your nails.) The AAD says ram’s horn nail can also happen if you have circulation problems that are the result of other medical conditions, such as type 2 diabetes.
Bottom line: If you have any concerns about your health from your nail changes, it’s best not to ignore them, Dr. Davis says.
You can start by scheduling an appointment with your primary care doctor if you have one and then get a dermatologist referral if needed. You’ll feel much better knowing that your nails—and your overall health—are well taken care of.
- StatPearls, Spoon Nails
- Journal of General Internal Medicine, Terry’s Nails and Lindsay’s Nails: Two Nail Abnormalities in Chronic Systemic Diseases
- Up to Date, Longitudinal Melanonychia
- International Journal of Research in Medical Sciences, Habit Tic Nail Dystrophy: a Case Report Affecting Single Thumb Nail
- Skin Appendage Disorders, Onychogryphosis: Case Report and Review of the Literature