5 Sneaky Toenail Clues That May Point to Hidden Health Problems

While most people are familiar with the appearance of healthy toenails — smooth, light pink, and evenly colored — changes in their look can sometimes raise concerns. When you notice spots, streaks, discoloration, or unusual textures, it may be more than a simple cosmetic issue. These differences can occasionally point to underlying health conditions and are worth having evaluated by a medical professional.

The content provided is for informational purposes only and is not intended to be a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified healthcare provider with any questions you may have regarding a medical condition.

Clubbed nails

Clubbed toenails cause the nails to widen and take on a rounded, club-like appearance. This condition is often linked to serious health issues such as heart disease, lung disease, gastrointestinal disorders, or cancers, though it can also be inherited.

Clubbing can develop gradually, with the nail bulging and pointing downward. Tips may swell and take on a red tint. It’s usually a response to low blood oxygen levels or other abnormalities. If you notice clubbing, see a doctor for evaluation. Further testing may be needed, especially for underlying conditions like lung cancer.

Blue or purple

If your toenails have taken on a blue or purple hue, it’s often a sign that your blood isn’t delivering enough oxygen to your extremities — a condition known as cyanosis. This can result from various issues, including heart and lung diseases that impair oxygenation.

In some cases, exposure to cold temperatures can cause temporary bluish discoloration due to reduced blood flow. However, persistent blue nails warrant medical evaluation to rule out underlying health problems.​

Additionally, blue nails can sometimes indicate poisoning, particularly exposure to toxic substances like cyanide or heavy metals.

Thick, yellow, or brownish nails

Toenails that thicken and turn yellow or light brown are often the first signs of toenail fungus. As the infection progresses, nails may become chalky, cloudy, or even opaque. In severe cases, they can crack, break, or detach from the nail bed.

Toenail fungus is an incredibly common issue, while it usually isn’t painful, ignoring it can lead to worsening nail health. In more advanced cases, nails can separate from the nail bed, and secondary infections may develop around the nail matrix.

Preventing fungus in the first place is all about keeping your feet clean and dry — especially in shared spaces like public showers. Regularly trim your nails straight across, and invest in shoes that allow your feet to stay dry and comfortable. Taking these steps can help keep your nails fungus-free and healthy.

Cracked toenails

Nails that look like they’ve been used to scoop sugar — concave or spoon-shaped — might be signaling iron deficiency anemia. This condition means your body isn’t producing enough healthy red blood cells, leading to fatigue and weakness. If your nails are doubling as tiny spoons, it’s time to consult a healthcare provider and possibly up your iron intake.

Beyond spooning, anemia can also cause your nails to become white and brittle. Iron deficiency anemia, in particular, can lead to nails that are pale and prone to breaking. If you notice these changes, it’s advisable to consult with a healthcare provider for appropriate evaluation and treatment. ​

Toenails with dark streaks

Dark streaks beneath the toenails can be linked to a range of health conditions, from harmless to more serious. In people with darker skin tones, these streaks are often due to a benign condition called linear melanonychia, where increased pigmentation (melanin) creates darker lines in the nail.

However, in rare instances, black streaks in the nails may signal more serious health issues, including skin cancer, endocrine disorders, connective tissue diseases, or other immune-related conditions. Because of this, any new or darkening discoloration in the nails should be checked by a podiatrist to rule out potentially serious medical concerns.

Be sure to check out our other article featuring alarming signs that could point to colon cancer.