What causes white spots under fingernails?

There are several possible causes for white spots under the fingernails, also known as leukonychia:

1. Trauma: Injury to the nail bed, such as from stubbing a toe or biting the nails, can cause damage to the nail matrix and result in white spots.

2. Fungal Infection (Onychomycosis): A fungal infection of the nails can cause white or yellow spots, as well as thickening and crumbling of the nail.

3. Nutritional Deficiencies: A lack of certain nutrients, such as zinc, protein, calcium, or vitamins A, B, or C, can contribute to white spots on the nails.

4. Medications: Some medications, including chemotherapy drugs, antimalarials, and antibiotics, can cause temporary white spots as a side effect.

5. Anemia: Iron deficiency anemia can lead to pale or white nails, including the appearance of white spots.

6. Liver Disease: In some cases, white spots on the nails can be a sign of underlying liver disease or hepatitis.

7. Genetic Factors: Some individuals may have a genetic predisposition to developing white spots on their nails.

8. Kidney Disease: Chronic kidney disease can sometimes cause white spots or bands on the nails.

9. Psoriasis: People with psoriasis, a skin condition that causes red, scaly patches, may also experience white spots on their nails.

10. Age-Related Changes: White spots can become more common with aging and nail growth changes.

11. Allergies: Allergic reactions to certain substances or medications can occasionally lead to white spots on the nails.

It's worth noting that white spots on the nails are usually harmless and resolve on their own over time as the nail grows out. However, if the white spots persist, change in appearance, or are accompanied by other nail or health symptoms, it's a good idea to consult a healthcare professional for proper diagnosis and treatment.