This article explains the causes and treatments for common nail problems (such as brittleness, vertical lines, horizontal lines, splitting, and white spots).

Nails break (or chip)

Nails can sometimes split or chip horizontally or vertically. When a nail splits vertically, it is called "longitudinal splitting of the nail," and this can occur either by splitting all the way to the base of the nail or only at the tip.

Nails become brittle and prone to cracking when they lose moisture due to factors such as drying from washing dishes or using nail polish remover, or when the keratin protein, the main component of nails, is deficient due to pregnancy, breastfeeding, or aging. The exact cause of onychoschizia (longitudinal splitting of the nail plate) is not clearly understood, but it can be caused by abnormalities in the cuticle, also known as the nail epithelium. Onychoschizia is treated with topical steroid medications, but if it does not improve, a tumor at the base of the nail should be considered.

Vertical lines (ridges) appear on the nails

This is a common symptom. It is also called longitudinal ridges on the nails.

Because it's caused by aging, it's often not very noticeable in your 20s, but it tends to increase and become more noticeable from around your 50s. It's a natural part of aging, so there's no need to worry too much, but as it progresses, your nails may become more prone to splitting vertically.

Horizontal lines (ridges) appear on the nails

A problem with the nail matrix can temporarily inhibit nail growth, causing horizontal lines to appear. The width of the horizontal line indicates the duration of the problem, and the depth of the horizontal line indicates the severity of the problem.

While nail-biting or external impact can cause transverse lines or grooves, these only appear on the injured nail. When a single transverse line appears on all nails, it is called a "Bawe's streak," and can be caused by febrile illnesses, infections, diabetes, medication side effects, childbirth, or zinc deficiency.

Uneven nails

A condition where horizontal grooves appear one after another on the surface of the nail, resembling waves, is called "navel nails" or "washboard nails." This condition can occur in healthy individuals and is more common in people who have a habit of pressing down on the skin covering the nail matrix with other fingers, and is especially frequently seen on the thumb.

Additionally, bumps or pitting may appear, resembling punctures caused by a sharp object; this condition is called "punctate depressions." Punctate depressions can also occur in association with psoriasis or alopecia areata.

Thin nails

Conditions such as hypochromic anemia, hyperthyroidism, peripheral circulatory disorders, and congenital keratinization disorders can affect the nail matrix, causing changes and thinning of the nails.

In addition, conditions such as lichen planus, lupus erythematosus, and chilblains can affect the nail matrix, leading to thinning of the nails and making them prone to vertical splitting.

The nail splits into two.

This condition, commonly known as "split nails," is medically called "onychoschizosis." The surface of the nail near the tip peels off in thin layers.

Similar to nail splitting, the cause is related to decreased moisture content and nutritional deficiencies in the nails. When excessive force is applied to the tip of a nail that has lost moisture, such as with nail clippers, it is more likely to cause split nails. For this reason, it is more common in winter when the air is drier than in summer. It can also be caused by iron deficiency anemia.

Nails become cloudy or white

Onychomycosis (nail fungus) causes the nails to become discolored and thickened. It is caused by infection with a type of fungus called dermatophyte, and is especially common in toenails.

Additionally, the toenail of the big toe may become cloudy, thickened, and have an uneven, curved surface. This condition is called onychogryphosis. It can be caused by trauma or ill-fitting shoes.

In addition, onycholysis, a condition where the nail separates from the fingertip and appears white, can occur in the fingernails and is overwhelmingly more common in women. Onycholysis can be caused by contact dermatitis, candidiasis, psoriasis vulgaris, etc. It can also be caused by nephrotic syndrome, in which large amounts of protein are excreted in the urine, anemia, diabetes, etc., but the cause is sometimes unknown.

White spots appear on the nails

This is a phenomenon where small white spots appear on the nails, and it is called punctate leukonychia.
This can occur due to abnormal nail growth caused by trauma or other factors, but there's no need to worry excessively.

My nails turn yellow.

Nails can turn yellow due to nutritional deficiencies, infections, carotenemia, or jaundice. If the nails are cloudy white to yellowish, it may be onychomycosis (nail fungus). If all the nails are yellowish and nail growth is inhibited, it may be yellow nail syndrome.

Yellow nail syndrome involves not only changes in the nails, but also edema from the lower leg (from the knee to the ankle) to the top of the foot, and pleural effusion (fluid accumulation in the chest).

Nails turn green

Infection with Pseudomonas aeruginosa, a type of bacteria, causes the nails to turn green. This bacterium thrives in humid environments, and if onycholysis (nail separation) is present, it can enter and multiply under the nail plate. Additionally, artificial nails such as sculpted nails or gel nails can create gaps between the nail plate and the nail, increasing humidity and making infection with Pseudomonas aeruginosa more likely.

Treat the underlying disease.

If your symptoms are caused by a nail disease, see a dermatologist for treatment. If the cause is a systemic disease such as an infection or diabetes, seek treatment at a medical institution that specializes in that particular disease.

Grow strong nails

While it's not possible to strengthen nails that are already brittle, it is possible to improve the quality of nails that will grow in the future. In terms of diet, focus on a balanced diet and be mindful of consuming protein and vitamins A, B, and D, which are essential for healthy nails.

In addition to a healthy diet, quality sleep, stress reduction, and a regular lifestyle are also important factors in growing healthy nails.

Make moisturizing your nails a regular habit.

For nails suffering from dryness, moisturizing care is essential. Fingernails, in particular, tend to dry out easily due to housework involving water, so be sure to moisturize them frequently with a nail moisturizing cream. Using creams that contain nail repair ingredients or those that have protective and coating properties is also a good idea.

Pay attention to how you trim your nails.

Applying too much force when cutting your nails can easily damage them. It's best to cut your nails when they are soft, such as after a bath. Start cutting little by little, checking the balance between both hands, and shape them as you go. Filing them at the end not only makes them look nicer but also prevents things from catching on them. For fingernails, be careful not to cut them too short, and shape them into a rounded shape that matches the flesh of your fingertips.