Nail Problems: What White Spots, Ridges and Colour Changes Mean

Most nail changes are harmless: small white spots usually come from minor knocks, nail biting or manicures, lengthwise ridges are common and increase with age, and brittle, peeling nails are often caused by frequent contact with water and detergents. A dermatologist should check a new or changing dark streak, a nail that is lifting or pitted, nails that become spoon shaped or curved, and red, swollen or painful skin around a nail, because these can point to infection, skin disease, a problem elsewhere in the body or, rarely, cancer.

Nails grow slowly and record what has happened to your body over months. That makes them a useful clue for doctors, but it also means many people worry about changes that are perfectly normal. This guide walks through the common ones.

What do white spots on nails mean?

Small white spots or flecks are called punctate leukonychia. DermNet describes them as the most common form of true white nail. They typically follow minor injury to the nail, such as:

• Nail biting or picking
• Manicures and pushing back cuticles
• Knocks and bangs
• Tight footwear, for toenails

The popular belief in India that white spots mean calcium deficiency is not supported by DermNet’s list of causes. There is no treatment needed for spots caused by trauma. They simply grow out with the nail, which DermNet notes takes around 6 to 9 months for a fingernail.

When should white nails worry you? If the whole nail turns white, if many nails change at once, or if the white area does not move forward as the nail grows, it may be something else. The American Academy of Dermatology (AAD) notes that white nails can be associated with liver disease or diabetes, and nails that are half white and half pink can be linked to kidney disease. White, crumbly areas, especially on toenails, can also be a fungal infection.

What do ridges on nails mean?

There are two very different kinds of ridges.

• Lengthwise ridges that run from the cuticle to the tip are common. The AAD says they are usually nothing to worry about, and they tend to become more noticeable with age.
• Deep grooves running across the nail, called Beau lines, mean that something slowed or stopped nail growth for a while. The AAD lists fever, injury, chemotherapy and major stress as causes. In India, it is common to notice these a few weeks after dengue, typhoid or another illness with high fever. They grow out once the cause has passed.

A central ridge or a washboard pattern on the thumbnails often comes from a habit of picking or pushing back the cuticle, which the AAD calls a habit tic. Stopping the habit lets a healthy nail grow out.

Why are my nails brittle and splitting?

The NHS lists the most common causes of nail problems:

• Injury or nail biting
• Hands often being in water or cleaning products
• Not trimming nails regularly, or cutting them at an angle
• Staining from smoking or heavy use of nail varnish
• Fungal nail infection

It also notes that nails naturally become thicker or more brittle with age, and can become harder, softer or more brittle during pregnancy.

Indian homemakers who wash dishes and clothes by hand are especially prone to brittle nails and to hand eczema. The AAD and NHS both recommend wearing rubber gloves for wet work and applying hand cream to the nails and fingertips after washing.

Less often, brittle or misshapen nails are a sign of a condition such as iron deficiency anaemia, thyroid disease, psoriasis or diabetes. If you have other symptoms, such as tiredness or hair fall, see our guide to hair fall linked to thyroid, iron and vitamin deficiency.

What does nail discolouration mean?

Colour or change	Common causes	Needs a doctor?
Small white spots	Minor injury, manicures, biting	No, grows out
Yellow, thick nails	Nail polish without base coat, smoking, fungal infection, lung disease	Yes, if thick, crumbly or spreading
Greenish black	Bacterial infection	Yes
Pale nails	Anaemia	Yes, for blood tests
Blue nails	Low oxygen in the blood	Yes, promptly
Half white, half pink	Kidney disease	Yes
Brown or black band	Usually harmless pigment, but sometimes melanoma	Yes, if new or changing
Orange or brown stain	Henna, hair dye, paint	No, grows out

The colour links in this table come from the AAD and DermNet. Remember that a colour change on its own does not mean you have a disease. It is a reason to get checked, not a diagnosis.

Yellow, thickened, crumbling toenails are very often a fungal infection. The NHS notes these infections can take a long time to treat. Our guide to nail fungus explains your options.

Is a dark line on my nail dangerous?

A brown or black band running the length of a nail is called longitudinal melanonychia. DermNet explains that it is much more common in people with darker skin, and that many brown skinned adults develop harmless pigment bands over time. It can also be caused by injury, nail biting, pregnancy, some medicines, nutritional deficiency, fungal or bacterial infection, and stains such as henna or hair dye.

However, a dark streak can occasionally be melanoma of the nail unit. DermNet notes that this type of melanoma most often affects the thumb or big toe, and that it is the most common type of melanoma diagnosed in deeply pigmented people. Because harmless bands are so common in brown skin, nail melanoma can be missed or diagnosed late.

See a dermatologist promptly if a dark band:

• Is new in an adult, or is changing in width or colour
• Affects a single nail, especially a thumb or big toe
• Is wide, uneven or has multiple shades of brown and black
• Has pigment spreading onto the skin around the nail
• Comes with nail splitting, bleeding or a lump

The AAD stresses that not every dark streak is melanoma, but it is always good to have one examined. Our guide to skin cancer signs in darker skin has more detail.

What other nail changes should a dermatologist see?

The AAD lists several changes that need a dermatologist’s assessment:

• Lifting nail (onycholysis). Often caused by fungal infection, psoriasis, aggressive manicures or cleaning under the nail with sharp objects.
• Redness and swelling around the nail (paronychia). May be an infection, especially in people whose hands are often wet.
• Pitting, small dents that look like they were made with a pin. These can be linked to psoriasis, eczema or alopecia areata.
• Spoon shaped nails (koilonychia), which can be a sign of iron deficiency.
• Clubbing, where nails curve over swollen fingertips. This can run in families but can also signal lung, heart, liver or bowel disease.
• Thick, overgrown nails that are hard to cut.

How can I keep my nails healthy?

The AAD recommends:

• Keep nails clean and dry
• Cut nails straight across and round the tips slightly
• File snags with an emery board
• Do not bite your nails or remove the cuticle
• Do not use your nails as tools
• Wear gloves for cleaning and washing dishes, and moisturise after washing hands
• Keep toenails short and wear well fitting shoes
• Wear slippers at pools and in shared bathrooms

People with diabetes should take extra care. The AAD advises seeking treatment early for any nail problem if you have diabetes or poor circulation. See our guide to skin care for diabetes.

When to see a dermatologist

The NHS advises seeing a doctor if a nail has changed shape or colour, or fallen off, and you do not know why, or if the skin around a nail is sore, red, swollen and warm. See a dermatologist if:

• You have a new or changing dark streak on a nail
• A nail is lifting, pitted, thickened or crumbling
• Your nails have become spoon shaped or curved
• Several nails have changed at once without an obvious cause
• You have nail changes along with skin rashes, hair loss or joint pain

Most nail changes turn out to be harmless, but the ones that matter are easier to treat early. Dr. Maria offers online consultations, and clear photos of your nails in daylight can help her advise whether an in person examination is needed.