Lines on your nails can have many causes, including aging, health conditions and nutritional deficiencies. If the lines are halfway down, it may be due to aging. This is usually not dangerous. However, deep ridges, brittle nails and darkening of the nail can be signs of health concerns. 

Lines on your nails can have many causes, including aging, health conditions and nutritional deficiencies. If the lines are halfway down, it may be due to aging. This is usually not dangerous. However, deep ridges, brittle nails and darkening of the nail can be signs of health concerns. 

Vertical ridges: Also known as longitudinal ridges, these lines are common with aging and are usually not dangerous. However, deep ridges, brittle nails or discoloration could be a sign of an underlying health condition. Skin conditions such as eczema or 

Very dry skin

Hypothyroidism, which can cause brittle, thick nails that may break or crumble easily. Lichen planus, an autoimmune disease that can cause longitudinal ridges, also called Beau's lines, in about 10% of affected people. These grooves can be caused by acute or chronic stress, illness, or local trauma.

White lines: Also known as leukonychia striata, these lines can be caused by microtrauma, onychomycosis or hereditary diseases.

Brownish-black vertical lines: Also known as melanonychia, these lines can be caused by trauma, infection, drug therapy or endocrine disorders.

Black lines: Most black lines on nails are not a cause for concern, but if your nail is bleeding or painful, or if the nail has changed for no known reason, you should contact a healthcare professional.

White lines or bands: Also known as Mees lines, these lines can be a symptom of a serious underlying health condition, such as arsenic poisoning or kidney failure