Infections
Nail fungus
Nail fungus (onychomycosis) is a common infection that makes nails thick, discolored, and brittle, most often on the toes. It is usually not dangerous, but it is slow to clear because nails grow slowly.
Reviewed by Raashid Haque, MD, board-certified dermatologist
For education only. This guide does not diagnose or treat any condition.
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Nail fungus usually starts from the same fungi as athlete's foot, so avoiding shared wet floors lowers risk.
Look for
- Quick-drying, waterproof material such as rubber, foam, or neoprene
- Textured sole for grip on wet tile
- Straps or a snug fit that hold well and do not rub the toes
Full details, cautions and sourcesAvoid
- Going barefoot in shared showers and locker rooms
- Sharing shoes or towels
- Storing damp sandals in a closed bag
These are products Dr. Haque has reviewed and recommends for different reasons. Unless a product is clearly marked 'Affiliate link,' it is not one. Most are not.
Food and lifestyle may play a part in Nail fungus too
Anti-inflammatory eating and lifestyleLearn about Nail fungus
Nail fungus is an infection of the nail caused by fungi, most often the same kinds that cause athlete's foot. It can affect toenails or fingernails, but toenails are far more common. The big toe is a frequent site. It becomes more common with age, and it is also more common in people who have diabetes, poor circulation, or a weakened immune system.
How it often looks: the nail may turn yellow, white, or brown. It can become thick, crumbly, ragged, or misshapen. Debris can build up under the nail, and the nail may lift off the nail bed. Sometimes there is a mild odor. It often starts at the tip or edge of the nail and slowly spreads toward the base.
Skin tone note: on lighter skin, the nail often looks yellow or white. On brown and Black skin, the nail may look more yellow-brown, gray, or dark, and normal nails can already have natural streaks or color. This can make nail changes harder to judge by eye alone.
Course: nail fungus rarely goes away on its own. It can spread to other nails and to the skin of the feet. Because toenails grow slowly, even successful treatment takes many months before the nail looks normal again.
Is it contagious? The fungi can pass from person to person through shared floors, showers, towels, and clippers, but many people exposed never develop it.
What it is not: many other conditions can look like nail fungus, including psoriasis, eczema, injury to the nail, and other nail diseases. Not every thick or discolored nail is a fungal infection.
Self-care
What it is
Everyday habits such as keeping nails short and clean, drying feet well, and wearing breathable shoes and clean socks.
Often considered when
Often considered for everyone with nail fungus and for people trying to lower the chance it returns. These steps are usually used alongside other treatments, not instead of them.
Less suitable or needs caution when
People with diabetes, numb feet, or poor circulation should be careful with home nail trimming and filing, since small cuts can lead to infections.
What to watch for
Cutting too short or too deep, or digging at the sides of the nail. Do not share clippers or files, and clean tools between uses.
How long to judge it
These habits help over time but do not by themselves clear an established infection.
Questions to ask
- How should I safely trim and file a thick nail?
- Should I replace or treat my old shoes?
- Is it fine to wear nail polish while this is going on?
Over the counter
What it is
Over-the-counter antifungal products used on the skin of the feet to treat athlete's foot, which is a common source of nail fungus.
Often considered when
Often considered when there is scaling, itching, or cracking between the toes or on the soles, since treating the skin may lower the chance the fungus keeps spreading to the nails.
Less suitable or needs caution when
These products usually do not clear fungus inside a thick nail on their own. They are less suitable if the skin is very red, weeping, or painful, or if a person has diabetes or a weak immune system and has not been seen by a clinician.
What to watch for
Skin irritation, burning, or an allergic rash. If the skin gets worse or does not improve, check in with a clinician.
How long to judge it
Skin changes are often judged over a few weeks, but nail changes take many months.
Questions to ask
- Is my foot skin infected too, and should it be treated?
- How can I tell if the skin is getting better?
- Could my household members be passing it back to me?
Prescription creams and gels
What it is
Antifungal liquids that are painted or applied onto the nail and the skin around it. Examples include ciclopirox, efinaconazole, and tavaborole.
Often considered when
Often considered for mild to moderate infection, when only part of one or a few nails is involved, or when oral medicines are not a good fit. Clinicians may also discuss thinning the nail to help the medicine reach the fungus.
Less suitable or needs caution when
Less suitable when the infection is severe, involves the nail base, or affects many nails, since the medicine may not reach deep enough. Pregnancy and breastfeeding should be discussed with a clinician.
What to watch for
Redness, irritation, or burning around the nail, and sometimes nail changes. These products need steady use over a long time, and they work less often than oral medicines in many people.
How long to judge it
Toenails often take many months of treatment before improvement can be judged, because new healthy nail has to grow in.
Questions to ask
- Is my nail mild enough for a topical medicine alone?
- How will we measure whether it is working?
- Would thinning the nail help?
Procedures
What it is
A clinician looks at the nail and may take a small clipping or scraping to check for fungus under a microscope or in a lab culture.
Often considered when
Often considered before starting medicines, because other nail conditions (such as psoriasis, injury, or other nail diseases) can look like fungus. It is also considered when the nail has not responded to earlier treatment or when the change looks unusual.
Less suitable or needs caution when
A sample is not a substitute for a visit if there is a dark streak or sign of infection; those may need other tests.
What to watch for
Clipping a nail is usually painless but can be uncomfortable if the nail is thick. Culture results can take weeks, and a test can sometimes miss fungus that is really there.
How long to judge it
Results from a lab usually come back in days to a few weeks.
Questions to ask
- Do you think this is fungus, or could it be something else?
- Should my nail be tested before any treatment?
- If the first test is negative, should it be repeated?
What it is
A clinician trims or files down the thick, crumbly nail, or uses medicated products to soften it. In some cases the nail is partly or fully removed.
Often considered when
Often considered when the nail is very thick or painful, when it makes shoes uncomfortable, or to help other medicines work better. Removal is usually kept for severe or stubborn cases.
Less suitable or needs caution when
Less suitable for people with poor circulation, numb feet, diabetes, or bleeding problems unless a clinician judges it safe.
What to watch for
Pain, bleeding, or infection after a procedure. The new nail can grow back misshapen, and fungus can still return.
How long to judge it
Comfort often improves soon, but the new nail takes many months to grow back.
Questions to ask
- Would thinning the nail make other treatments work better?
- What would removal involve and what is the recovery?
- How will I care for the area afterward?
What it is
Devices that aim laser or light energy at the nail with the goal of reducing the fungus. They are offered at some clinics, usually for a fee.
Often considered when
Sometimes discussed when a person cannot take oral medicines or has not had success with topical treatment. The honest picture is that studies so far are small and mixed, and it is unclear how well these devices compare with standard medicines.
Less suitable or needs caution when
Less suitable for people looking for a guaranteed result, since results vary and the nail still has to grow out. Costs are often not covered by insurance.
What to watch for
Warmth or mild discomfort during treatment. Ask how many sessions are expected, the total cost, and what happens if the nail does not improve.
How long to judge it
Any change in the nail takes many months to judge, whatever the device.
Questions to ask
- What does the research show for the device you offer?
- What is the total cost, and is it covered by insurance?
- What is the backup plan if my nail does not improve?
Pills
What it is
Antifungal pills taken by mouth that reach the nail through the bloodstream. Examples of the class include terbinafine and itraconazole.
Often considered when
Often considered when the infection is moderate to severe, involves several nails, is painful, or has not responded to topical treatment, and when the diagnosis has been confirmed.
Less suitable or needs caution when
Less suitable for people with liver disease and may be less suitable during pregnancy or breastfeeding. They can interact with many other medicines, including some for heart conditions, cholesterol, and mood, so a clinician reviews a person's full medicine list first.
What to watch for
Possible stomach upset, headache, rash, or taste changes. Rarely, liver problems can occur, so clinicians may check blood tests. Tell a clinician right away about yellow skin or eyes, dark urine, severe tiredness, or a serious rash.
How long to judge it
The medicine is taken for a limited course, but the nail keeps growing out for months after, so the final result may not be visible for a year or more.
Questions to ask
- Which of my medicines or supplements could interact with this?
- Do I need blood tests before or during treatment?
- What are my chances of success given my age and health?
Lifestyle and holistic
What it is
A plant oil with some antifungal activity in the lab, sometimes put on the nail at home.
Often considered when
Sometimes tried by people who prefer natural options or who have a very mild change. Small studies hint at possible benefit, but the evidence is early and not strong enough to say it reliably clears nail fungus.
Less suitable or needs caution when
Less suitable for people who react to fragrances or essential oils, or who have sensitive skin. It should not be swallowed, and it can be harmful to pets.
What to watch for
Skin redness, itching, or an allergic rash (contact dermatitis). Do not rely on it if the nail is getting worse, painful, or infected.
How long to judge it
Even if it helps, changes would take many months to show in a toenail.
Questions to ask
- Is it reasonable to try this, and could it irritate my skin?
- Should I still get the nail tested?
- Would it interfere with other treatments?
What it is
Soaking the foot in diluted vinegar, or using products such as mouthwash, baking soda, or menthol rubs, is widely shared online as a home remedy.
Often considered when
Often tried because they are cheap and easy to find. Honestly, there is little good research showing that these clear nail fungus, and most support comes from personal stories rather than controlled studies.
Less suitable or needs caution when
Less suitable for people with diabetes, numb feet, broken skin, or poor circulation, since soaking can irritate or macerate skin and hide early problems. Prolonged soaking can also keep feet damp, which fungus likes.
What to watch for
Stinging, dryness, or irritation of the skin. Watch for any worsening or signs of infection, and avoid delaying a proper diagnosis.
How long to judge it
If a nail has not improved after a reasonable period, it may be worth a visit instead of continuing.
Questions to ask
- Is there any harm in trying a home remedy first?
- How long should I wait before coming back?
- Are there foot soaks I should avoid with my health history?
Things that make nail fungus more likely include:
- Athlete's foot (tinea pedis): the same fungus often spreads from the skin of the foot to the nail.
- Warm, damp feet: sweaty feet, tight or non-breathable shoes, and damp socks.
- Walking barefoot in pool areas, locker rooms, and shared showers.
- Nail injury: repeated pressure from shoes, sports, or small cracks in the nail.
- Health factors: older age, diabetes, poor circulation, a weakened immune system, or a family history of nail fungus.
- Shared items: nail clippers, files, and towels.
- Artificial nails or polish worn for long periods, which can trap moisture.
| Topic | Evidence | What it means |
|---|---|---|
| Blood sugar and circulation | Established | Diabetes and poor circulation raise the chance of nail fungus and of foot complications. Good diabetes care and regular foot checks are well supported as part of protecting the feet. |
| Sweat, shoes, and socks | Established | Damp, warm feet help fungus grow. Breathable shoes, moisture-wicking socks, changing socks when they get wet, and letting shoes dry between wears are commonly advised. |
| Treating athlete's foot early | Promising | Athlete's foot is a common source of nail fungus, so treating foot skin is widely considered sensible for lowering the chance of spread. Studies directly measuring how much this prevents nail infection are limited. |
| Biotin and nail supplements | Early | Some people take biotin or similar supplements for nail health. They have not been shown to treat a fungal infection, and biotin can interfere with some blood test results, so tell your clinician if you take it. |
Read: Anti-inflammatory eating
Avoid very restrictive diets, especially for children, unless a clinician is guiding you.
Nail fungus ·
When to get care soon
- A dark streak or dark spot under a nail, especially a single nail, a streak that is widening, or dark color that spreads onto the skin next to the nail. Nail fungus can look like other nail problems, including rare skin cancers, so a new dark change should be checked.
- Signs of infection: spreading redness, warmth, swelling, pus, or throbbing pain around the nail.
- Diabetes, poor circulation, or a weakened immune system with any nail or foot change, a foot sore, or a crack in the skin.
- Pain when walking or wearing shoes, or a nail that is lifting, bleeding, or growing into the skin.
- Spreading to several nails or to the skin of the feet or hands.
- Fever or red streaks moving up the foot or leg.
- Not sure what it is, or the nail is not improving with care, or the nail change started after an injury and does not grow out.
About the reviewer
Raashid Haque, MD
Board Certified Dermatologist · Charlotte, NC
- 25+ years of clinical experience
- Dermatology at University of Oklahoma - Chief Resident
- Internship at Baylor College of Medicine
- LSU School of Medicine Shreveport - Valedictorian, AOA