Yellow nails are often caused by a fungal infection, especially when the nails become thick, delicate or start to crumble. But sometimes yellow nails can be a sign of more serious health problems such as lung disease, diabetes or thyroid problems.
On what to watch:
Yellow or yellowish-green nails
Thickened or crumbly nails
Nails grow slowly or separated from nails
Possible reasons:
Fungal nail infection
Lung diseases such as chronic bronchitis
Problems with diabetes or thyroid gland
Psoriasis nails
