What Your Nails Say About Your Health

White marks? Cracked tips? Dark lines? Nails can be a window to learning more about your wellbeing.
By Donna MacMullin
What Your Nails Say About Your Health

There two types of people in life: those who have their nails immaculately groomed at any given moment, and those whose nails slip right to the bottom of their to-do list. No matter which way you swing, however, the surface of your nail can be an open door to learning more about your overall health and wellbeing. Studies on surface colour, texture and structure have found nails are often linked to nutrient deficiencies and illnesses. Here are five signs that your nails might be trying to tell you something.

Dry, cracked or brittle nails

Sometimes dry and brittle nails are a reflection of lifestyle changes or the products we use, such as excessive exposure to water, nail polish remover or harsh detergents. But if your nails are chronically brittle, thin or splitting, it could be time to see your doctor. “When people have dry skin, hair or nails, it can be an indicator of a low-functioning thyroid,” says Dr. Sandy Skotnicki, an associate professor of dermatology at the University of Toronto. A 2013 study on hypothyroidism — where your thyroid gland doesn’t produce enough thyroid hormone to keep the body running normally — in the Indian Journal of Endocrinology and Metabolism indicates that gender and age have significant association with the condition, with the highest prevalence found in women aged 46 to 54 years. Your physician will give you a blood test to check thyroid hormone levels.

Ridges or bumps

It turns out wrinkles don’t just appear on your skin: over time, you may notice your nails becoming more textured too. “As we age, longitudinal ridging on the nails is normal,” says Dr. Skotnicki. However, horizontal ridging can signify something very different. “Sometimes if you’re really sick, like if you have a severe fever or illness, your nails will stop growing, which will cause a horizontal line on the nail called Beau’s Lines,” says Dr. Peter Vignjevic, a dermatologist and assistant professor of medicine at McMaster University. “It’s a sign of stress,” he adds. And what if your nails appear bumpy? “Pits or dots could indicate psoriasis (a common chronic inflammatory skin condition that involves red, scaly patches) elsewhere in the body,” says Dr. Skotnicki. A 2015 Canadian study linked fingernail changes in more than 90% of patients with psoriatic arthritis.

Dark lines

If you’ve ever hit a fingernail with a hammer (ouch!), you’ll know it can take a while for that ugly dark bruise to heal. But sometimes dark patches or lines can appear beneath your nail bed for no apparent reason, which is worth speaking to your doctor about. “Most people don’t know that Bob Marley died of acral lentiginous melanoma, which can be indicated by a black streak under the nail,” says Dr. Skotnicki. “[This] is more common in people of colour, and it’s also more common with age.”

Yellow nails

A yellowish tinge on your nails is most commonly caused by nicotine if you smoke or frequently apply nail polish. But “if the nails are yellow and you have lifting of the nail bed, it could indicate a fungal infection,” says Dr. Skotnicki. A physician will give patients with such symptoms a prescription that kills the fungus and prevents it from spreading. In rare cases, yellow nails can be associated with more serious conditions such as lymphedema (a build-up of lymphatic fluid in tissues), or respiratory disease. These health issues can cause the nails to thicken as new growth slows, leading to a yellowish discolouration.

White marks


If you work with your hands, chances are you’ve had a few broken nails or knocks to the nail bed that leave a white mark. “Small white marks are called traumatic leukonychia and are harmless,” says Dr. Vignjevic. But if it’s more than a small mark and half of your nail is appears white, “it can be a condition called Terry’s Nails, which is associated with liver disease or severe kidney disease.” In 1954, Dr. Richard Terry was the first to describe this abnormality in the nails of patients with cirrhosis (a condition that results from permanent damage or scarring of the liver). In this case, the nail has a characteristic “ground glass” appearance, with no lunula — the white crescent-shaped area at the base of a fingernail.

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Originally published June 2017; Updated February 2018.


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