What Does Nail Fungus Look Like? Stage-by-Stage Guide
Short answer: Nail fungus usually starts as a small color change at the edge of one nail, then thickens, turns yellow, white or brown, becomes brittle and may lift from the nail bed. In advanced cases the nail is thick, crumbly and distorted. Many conditions look similar, so a lab test is the only way to be sure it is fungus.
Key takeaways
- The first sign is usually a different color on part of the nail (AAD); later signs are thickening, debris, brittleness and lifting.
- Stages are a helpful description, not a medical grading: nails do not all progress in the same order or at the same speed.
- Psoriasis, injury, bacterial stains and, rarely, melanoma can look like fungus. A nail sample test avoids guessing.
- The earliest signs are covered separately in our early-stage guide; this page follows the nail through the later stages.
In this guide
- The stages at a glance
- Moderate stage: what changes
- Advanced stage: thick, lifted and crumbly
- What the color can suggest (and cannot)
- What nail fungus is often confused with
- When to get tested
- How quickly do the stages progress?
- Tracking your nail over time
- A note on pictures
- Frequently asked questions
- Sources
The stages at a glance
The American Academy of Dermatology says the first sign of nail fungus is usually a different color on part of a nail, and that other signs include brittle nails that crack or split, debris building up under a discolored nail, a nail that lifts, and redness of the surrounding skin. The NHS adds that infections usually start at the edge of the nail and often spread across the whole nail, which may turn white or yellow, crumble, and sometimes lift off (NHS).
Doctors do not use a single official “stage” scale that every source shares, so treat the table below as a plain-language guide.
| Stage | What you may notice | What it might feel like |
|---|---|---|
| Early | A small white, yellow or brown patch at the tip or side; nail still smooth | Usually nothing. See early stage nail fungus symptoms for details. |
| Moderate | Larger area of color change; nail thicker; chalky debris under the free edge; edges may crumble | Nail may catch on socks; mild pressure in shoes |
| Advanced | Most of the nail is thick, yellow-brown, distorted or crumbly; the nail lifts from the nail bed | Pain in shoes, difficulty trimming, sometimes odor |
| Severe or total | The whole nail is thick and deformed or has partly fallen off; skin around it may be red or sore | Often painful; may need a podiatrist |
Moderate stage: what changes
As the fungus spreads under the nail plate, the color change widens and the nail often thickens. The nail may look dull or opaque, and a chalky material can collect under the nail. The edges become brittle and may split or crumble. The infection can reach neighboring nails or the skin between the toes, which is why athlete’s foot matters: the AAD notes it can spread to the nails.
At this stage, most people notice that nail clippers struggle with the nail. If it is hard to trim safely, see what a podiatrist does and clippers for thick nails.
Advanced stage: thick, lifted and crumbly
In advanced infections much of the nail is involved. It can be thick, yellow to brown, and distorted, with a gap under the nail where debris collects. The nail may separate from the nail bed, which can hurt when shoes press on it and gives bacteria another route in. The AAD says treatment is especially important if the nail causes pain or discomfort, or makes walking or standing difficult.
A nail that is loose or falling off is covered in toenail fungus and a nail falling off. People with diabetes, poor circulation or a weakened immune system should not wait at this stage; see toenail fungus and diabetes and can toenail fungus kill you?.
What the color can suggest (and cannot)
White, yellow, brown and dark-yellow shades are common with fungus. Green, black or blue tones are more often something else, although a lab is needed to be sure. Our page on nail fungus color goes through each. Color alone cannot confirm fungus, since staining from polish, injury, psoriasis and bacterial infection can look similar.
What nail fungus is often confused with
| Looks like fungus | Clues it may be something else | Read |
|---|---|---|
| Bruise under the nail | Dark red/purple/brown; follows a knock; moves forward with growth rather than spreading | Bruised nail vs fungus |
| Nail psoriasis | Pitting, oil-drop spots, psoriasis elsewhere on the body | Nail fungus vs psoriasis |
| Yellow nails from other causes | Polish stains, age, other health conditions | Yellow toenails without fungus |
| Bacterial stain | Green or blue-green discolor, often with lifting | Fungus under acrylic nails |
| Melanoma under the nail | A new dark band or streak, pigment on the skin next to the nail | Toenail fungus vs melanoma |
When to get tested
If the nail is thick, discolored or painful, get it checked before buying treatments. The NHS says a GP may take a sample of the nail and test it to identify the type of infection before prescribing tablets. For the types a lab can find, see types of nail fungus. For who to see, read podiatrist or dermatologist.
Treatment depends on the findings. The AAD says prescription medication is needed and that on the big toe it may take a year or longer to see a clear nail. Nail fungus rarely clears without treatment; see will toenail fungus go away on its own?.
How quickly do the stages progress?
There is no fixed timetable. Some infections stay mild on one nail for a long time; others spread over months. Toenails grow slowly, so the visible change from the first spot to a thick nail is usually gradual. The AAD says that on the big toe it may take a year or longer to see a clear nail after an infection is cleared, which is also a reminder that thick nails are often slow to improve even once the fungus is gone.
Factors that tend to speed things along include ongoing athlete’s foot, damp shoes, repeated nail injury and conditions that affect circulation or immunity. Our page on how fast nail fungus spreads covers spread between nails and people.
Tracking your nail over time
Because stages are gradual, tracking helps. Take a photo in daylight every month, note how much of the nail is affected, and write down any new symptoms such as pain or redness. If the nail is clearly spreading week over week, thickening, or hurting, that is a reason to book an appointment now rather than later. If the nail grows out clear from the base after a knock, that points away from fungus. Bring your photos to the visit; they help your clinician see the trend.
A note on pictures
Many readers search for photos of nail fungus. We do not publish unlicensed clinical photographs here, and we do not recommend diagnosing yourself from pictures: lighting, skin tone and several look-alike conditions make matching unreliable. A phone photo of your own nail, taken in daylight each month, is more useful for tracking change and for showing your clinician.
Get medical advice promptly if
a nail is painful, swollen, oozing, bleeding or lifting; the surrounding skin is red, hot or spreading red; you have a fever; you have diabetes, poor circulation or a weakened immune system; or there is a new dark streak or band in the nail (the AAD says to see a board-certified dermatologist for any new dark band).
Questions to ask your doctor or clinician
- Is this fungus? Can a nail sample be tested?
- How advanced is the infection, and does that change the treatment?
- Could this be psoriasis, injury, a bacterial stain or something else?
- What can I expect month by month, and what signs mean I should come back?
- Should I have the nail trimmed or debrided by a professional?
Frequently asked questions
What does early nail fungus look like?
Usually a small white, yellow or brown patch near the tip or side of one nail, with the nail otherwise normal. Our early-stage page describes it in more detail.
What color is nail fungus?
Often white, yellow or brown. Green, blue or black tones are more often another cause, but only a test can confirm.
Does nail fungus hurt?
Early on, usually not. Pain tends to appear later, when the nail is thick or lifting and shoes press on it.
Is it fungus or a bruise?
A bruise is usually dark red, purple or brown, follows a knock and grows out with the nail. Fungus spreads. If unsure, ask a clinician.
How can I be sure it is fungus?
A clinician can send a nail sample to a laboratory. Looks alone are not reliable.
Related reading
- Early stage nail fungus symptoms
- Types of nail fungus
- Nail fungus color: what it means
- Bruised nail vs fungus
Sources
- AAD nail fungus overview https://www.aad.org/public/diseases/a-z/nail-fungus-overview
- NHS fungal nail infection https://www.nhs.uk/conditions/fungal-nail-infection/
- AAD nail melanoma https://www.aad.org/public/diseases/skin-cancer/types/common/melanoma/nail-melanoma
Medical disclaimer. This page is general educational information, not medical advice, and it has not been reviewed by a doctor. It cannot diagnose your nail. Always talk to your doctor, podiatrist, dermatologist or pharmacist about your situation; see our medical disclaimer. Last reviewed by our editorial team: 20 October 2026.
