Medically reviewed by Dr. A.M. van Coevorden, dermatologist
Nail fungusthickened, discoloured and crumbling nails
Nail fungus, also called onychomycosis, is a nail infected by a fungus that becomes thicker, discoloured and crumbly. It most often affects the toenails, especially the big and little toe. It usually causes no physical symptoms, but the nail looks different.
What is nail fungus?
Fungi are micro-organisms found everywhere in our surroundings and invisible to the naked eye. They can infect the skin and also grow into the nail. The medical term is onychomycosis.
How do you get nail fungus?
Fungal spores are everywhere, for example in gyms, swimming pools and other public spaces. They spread easily and survive for a long time, even a wash at 40 degrees. Contact with fungi is therefore hard to avoid completely, and it is usually unclear where the infection was picked up.
What symptoms does nail fungus cause?
The fungus changes the nail: it often becomes thicker, fragile and crumbly and takes on a yellowish or brownish colour. The nail grows more slowly and is harder to cut, and sometimes comes loose. The infection usually starts at the tip of the nail and slowly grows towards the nail fold; left untreated the whole nail can be affected. Nail fungus rarely affects the fingers; toenails are affected most often. Sometimes there is athlete's foot on the skin of the feet at the same time, with itch, flaking and sometimes redness.
Is nail fungus contagious?
Yes. Nail fungus is contagious. Household members can become infected, although this does not happen often. Some people are more susceptible than others, especially older people and people with diabetes, and people whose immune system is weakened by illness or medicines.
How is the diagnosis made?
An affected nail often looks clearly different, but the diagnosis cannot be made reliably from the outside, because a thickened yellow nail can have several causes. Additional tests are therefore done: the dermatologist can examine a scraping of the nail under the microscope or send it to the laboratory. How long the result takes varies by method.
What treatments are there?
Nail fungus usually causes no physical symptoms and treatment is not always needed. It is important, though, that the skin around the nails and between the toes has no small wounds, because these increase the risk of erysipelas, especially in people with diabetes. Nail fungus is hard to treat. Local products such as cream or a brush-on lacquer do not penetrate the nail enough, and laser treatment is not effective. Antifungal tablets or capsules work best: they kill the fungus in the nail matrix, after which a fungus-free nail grows out. The course usually lasts two months for fingernails and three months for toenails; because the medicine is built into the nail, it keeps working for months afterwards. In the end it often takes six to nine months before the toenail is completely clear. Tell your doctor which other medicines you take, because these tablets do not combine with all medication, and they cannot always be given if there are liver problems.
Can nail fungus be cured?
Nail fungus can usually be treated well, but treatment takes a long time. After the course there is a risk that the infection returns; how great that risk is differs per person. To prevent reinfection through shoes or socks, it is wise to wash socks at 60 degrees and treat shoes with miconazole powder.
How can you prevent nail fungus?
Fungal spores are everywhere, so preventing it completely is not possible. You can reduce the risk by keeping the feet dry and drying them well after washing, including between the toes; wearing cotton socks and breathable footwear; putting on clean socks every day and washing them at at least 60 degrees; alternating shoes so they can dry; always wearing flip-flops in public spaces; and trying on new shoes only with your own socks.
Frequently asked questions about nail fungus
Is nail fungus contagious?
Yes. Household members can become infected, although this is not common. Flip-flops in public spaces and clean socks reduce the risk.
Do creams or lasers help against nail fungus?
Barely. Local products do not penetrate the nail enough and laser treatment is not effective. Antifungal tablets work best.
How long does treatment take?
The tablet course lasts two to three months, but it often takes six to nine months before a toenail has grown out completely clear.
Do I always have to treat nail fungus?
Not always. The nail usually causes no symptoms. Treatment matters most when there are wounds around the nail, especially with diabetes, because of the risk of erysipelas.
How do I prevent reinfection?
Wash socks at 60 degrees, treat shoes with miconazole powder, keep the feet dry and wear flip-flops in public spaces.