Your fingernails can reveal important clues about your health. While brittle or discolored nails are usually harmless—often caused by age, moisture, or poor nutrition—some changes may signal underlying medical conditions.

“For the general population, nail health is most often an indicator of poor nutritional intake or poor digestion,” says Dr. Sara Norris. Brittle, peeling nails are common and usually diet-related.

**Beau’s lines** are deep grooves across the nails and may result from serious illness, injury, or stress like COVID-19 or chemotherapy. “This temporary disturbance of nail growth is usually caused by severe illness or infection,” explains Dr. Bhavini Shah. Nutrient deficiencies or harsh chemicals can also contribute.

**Clubbing**, where nails curve over swollen fingertips, may point to heart or lung diseases. It can be gradual and linked to conditions like lung cancer, congenital heart defects, or liver disease. “If you notice red or purple lines and didn’t injure your nail, you might want to book a doctor’s appointment,” says Shah.

**Spoon nails** (koilonychia) curve inward and often signal iron-deficiency anemia. Causes include poor nutrition or digestive issues. Fortunately, iron supplements and a proper diet can usually help.

If nail changes persist or come with other symptoms, consult a doctor.