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Onycholysis
The nail lifts from the free edge, not from the root. What has lifted does not reattach — it grows out, and on the hand that takes four to six months.
Also known as: onycholysis · nail lifting from the bed · white nail from the edge · detached nail plate
Open in the tool — with search and all the links →This compilation is for information and replaces neither medical diagnosis nor treatment. If you have symptoms, see a doctor.
The nail plate lifts from the bed, almost always from the free edge, less often at the side. Under the lifted part there is air, and air looks white — so a white area, often with a map-like border, travels slowly towards the root. It does not hurt, and that is exactly why it goes unnoticed for so long.
The most important number is time. What has lifted does not reattach; it has to grow out. A fingernail grows about three millimetres a month and is replaced in four to six months, a toenail grows about one millimetre a month and needs twelve to eighteen months. Judging whether a treatment works needs that span — before it, all one sees is whether the border travels further back or stands still.
The causes sort well. Mechanical is the commonest: cleaning under the nail, long nails that catch on things, a knock, gel or acrylic work, the removal of false nails. Then come a nail fungus (thickened, yellowish, crumbly beneath), psoriasis (pits as if made with a needle, an oil spot, usually several nails), constant contact with water, soaps and solvents, and medicines that make the skin sensitive to sun — the nail then lifts after a sunny day, often on several fingers at once. If all nails are involved evenly, the look goes inwards, to the thyroid for instance.
Two colours mean different things. A greenish-black shimmer under the lifted plate comes from a bacterium that uses the moisture under the nail; it is stubborn but harmless and goes with keeping things dry. A single brown to black length-wise band, on the other hand, coming out of the root, widening or colouring the skin of the nail fold too, is a different question and belongs looked at.
The commonest mistake is also the most understandable: cleaning under the lifted nail because it looks dirty. Every cleaning levers the plate a little further off and lengthens the whole thing by months.
The lifted part is cut back close to the border so it catches on nothing. Do not poke under the nail: every cleaning levers the plate further off and enlarges the gap where moisture collects.
The gap under the nail holds water. For wet work, gloves with cotton beneath, really dry the fingertips after every wash, no long soaking. That is the measure that clears the green shimmer and brings the lifting to a stop.
Shavings from the border zone under the nail go to the laboratory: microscope, culture or PCR. The sample belongs before the first antifungal — after it, it is falsely negative for weeks. Roughly every second suspicious nail is free of fungus, and then a treatment lasting months would be for nothing.
Fingernail: about three millimetres a month, four to six months to full replacement. Toenail: about one millimetre a month, twelve to eighteen months. Seeing no improvement after four weeks is not too little effect but too little time.
Gel, acrylic, hardeners and above all the removal of false nails pull on the plate. A clear varnish to cover it does no harm; the applying and removing with files and solvents is the problem, not the colour.
If all ten are evenly involved, TSH and ferritin are worth doing — a thyroid disorder and empty iron stores change nail formation on all fingers at once. With a single lifted nail that is not the trail.
It is not the nail that turns white but the space beneath it. The border is sharp and often irregular like a coastline. Mark where it stands today — in four weeks you will see whether it moves on.
Which is why months often pass. If it does hurt, throbs, or the nail fold is red and swollen, it is no longer only about the lifting — the surroundings are inflamed.
A single nail speaks for something local: pressure, a knock, a fungus, a patch of psoriasis. All nails evenly speak for something internal or for a substance all the fingers met.
Small dents in the plate as if made with a needle, and a yellowish-brown patch that looks like oil seeping through — both point towards psoriasis, even when the skin shows nothing at the moment.
That speaks for a fungus. It is not proof: roughly every second suspicious nail is negative in the laboratory. Before a treatment lasting months the sample is therefore doubly worthwhile.
A bacterium settles in the moist gap and colours it green to almost black. It is harmless and goes when the gap stays dry and the lifted part is cut short — it is not a sign of uncleanliness but of moisture.
Worth doing if several or all nails are involved. Both over- and underactivity change nail growth and adhesion; with a single nail it explains nothing.
An empty store makes the plate thin, brittle and in marked cases spoon-shaped. As the sole cause of lifting on one finger it does not qualify — as a companion across several nails it does.
Important for nail formation in the root, not for adhesion to the bed. A shortfall therefore shows on the regrowing nail — thin, brittle, ridged — not on the lifted area.
Involved in building the nail keratin. In marked shortfall nails become white-spotted and brittle; that then affects all nails and goes together with skin and hair.
The known figures come from veterinary medicine — brittle hooves in horses — and from small series on brittle nails, usually 2.5 mg a day over six months. On lifting caused by pressure, fungus or psoriasis, biotin does nothing. Important for the laboratory: biotin distorts thyroid and cardiac values; it is left out for two days before a blood draw.
The thyroid hormones set how fast the nail is made and how firmly it holds to the bed. If that changes on all ten nails at once, the thyroid belongs in view — with a single nail it does not.
A lifted plate on one finger has nothing to do with food. Diet only becomes the subject when all nails regrow thin and brittle — and then it is about protein, iron and zinc over months, not a product over days.