A dark brown or black line running lengthwise along a nail can have several explanations, including pigmentation, nail injury, or certain medical conditions.
However, a new or changing dark line on a single nail should be examined by a dermatologist, especially if it becomes wider, has irregular colors, or extends onto the surrounding skin. In some cases, these changes can indicate subungual melanoma, a rare type of skin cancer that develops beneath the nail.
Not every dark line is cancer, but it should not be ignored when it has concerning features.
4. White Lines or Spots on the Nails
Small white spots are common and often result from minor injuries to the nail. They usually grow out as the nail grows.
White lines or widespread changes affecting multiple nails can have other causes, so persistent or unusual changes should be assessed in the context of other symptoms.
5. Brittle Nails That Break Easily
Nails that frequently split, peel, or break may be affected by:
- Frequent exposure to water and cleaning products.
- Excessive use of nail polish removers.
- Iron deficiency.
- Thyroid disorders.
- Certain skin conditions.
If brittle nails persist, a healthcare professional can determine whether testing for an underlying condition is appropriate. Supplements should not be taken in high doses without establishing whether a deficiency exists.
6. When Should You See a Doctor?
Consider seeking medical advice if you notice:
- A new dark line on one nail, especially if it changes.
- A nail that becomes detached, distorted, or unusually thick without an obvious cause.
- Persistent nail changes accompanied by unexplained fatigue, weight loss, or other symptoms.
- Pain, swelling, bleeding, or a lump around the nail.
Sudden changes affecting multiple nails may also warrant assessment, particularly after a significant illness or when accompanied by other symptoms.
Can You Prevent Nail Problems?
You can support healthy nails by maintaining a balanced diet, protecting your hands from harsh cleaning products, moisturizing your nails and cuticles, and avoiding repeated trauma to the nail bed.
Protein, iron, zinc, and other nutrients contribute to normal nail growth, but nail appearance alone cannot reliably diagnose a nutritional deficiency or a serious disease.
The most important thing to remember: Vertical lines on your fingernails are usually a normal part of aging, and they do not automatically indicate cancer. Pay attention to new, unusual, or progressive changes rather than relying on frightening social media headlines.
If you have noticed lines on your nails, the most useful next step is to identify their appearance: Are they vertical ridges, horizontal grooves, white lines, or dark brown or black lines? Each pattern can have a different explanation.
See more on the next page
