Free self-check

Is it really toenail fungus?

About half of discolored or thick toenails turn out not to be fungal. Answer a few questions, match your nail to our pictures, and see which of 15 common causes fits you best.

15possible causes checked
6picture questions, including a tap-the-toe map
2 or 6minutes, quick or full check

This self-check is for general information and isn't medical advice or a diagnosis. Nail conditions often look alike, and only a doctor's examination and a lab test of a nail clipping can confirm a fungal infection.

In a nutshell

Not every thick or yellow toenail is fungus. About half turn out to be something else, such as psoriasis, an old injury, or polish staining. This free check compares your nail with 15 common causes in 2 to 6 minutes and tells you when to see a doctor.

What the Nail Check looks for

Thick, yellow, or discolored toenails have many causes, and they often look alike. The check compares your answers with these 15 conditions:

  • Toenail fungus: yellow-brown, thick, crumbly nails that change slowly.
  • White surface fungus: chalky white patches on top of the nail.
  • Nail psoriasis: pits, oil-drop spots, and lifting, often on fingernails too.
  • Bruise under the nail: a dark patch after an injury that grows out.
  • Repeated-impact damage: thickening from running, sport, or tight shoes.
  • Nail polish staining: an even yellow-orange tint on a smooth nail.
  • Green nail syndrome: a bacterial infection that turns the nail green.
  • Loose nail: a nail lifting off the nail bed without infection.
  • Age-related nail changes: thicker, ridged, slower-growing nails after 60.
  • Nail lichen planus: thinning nails with ridges running lengthwise.
  • Thick, claw-shaped nail: a very thick nail that curves over.
  • Ingrown nail or nail-fold infection: red, swollen, painful skin at the edge.
  • Medication-related change: color changes caused by some medicines.
  • Yellow nail syndrome: a rare condition affecting all 20 nails.
  • Minor, harmless marks: white spots and ridges from small knocks.

Frequently asked questions

How can I tell if I have toenail fungus or something else?

Look at the color, the surface, and where the change started. Each cause has its own signs:

  • Toenail fungus: yellow or brown color, thickening, and crumbling that start at the tip and spread slowly.
  • Nail psoriasis: tiny pits and oil-drop spots.
  • Injury: a dark patch that grows out with the nail.
  • Nail polish: an even, smooth stain with no thickening.

Only a nail clipping test can confirm fungus.

Can nail polish turn toenails yellow?

Yes. Dark polish worn without a base coat can stain nails an even yellow-orange. Unlike fungus, the nail stays smooth and shiny, and the stain grows out over a few months once you take a break from polish and start using a base coat.

Is a black toenail always a bruise?

No. Most dark patches after an injury are trapped blood that grows out over months. But a dark streak running from the cuticle to the tip, especially one that widens or spreads to the skin, needs a dermatologist's check because it can rarely be a sign of melanoma.

How long does it take to treat toenail fungus?

Usually 12 to 18 months, because the infected nail has to grow out completely. Topical treatments work best on mild cases that haven't reached the cuticle. Stopping too early is the most common reason treatment seems to fail.

When should I see a doctor about a toenail?

See a doctor if you have diabetes or poor circulation, if the skin around the nail is red, swollen, or leaking pus, if there's a dark streak or a dark patch that isn't growing out, or if home treatment hasn't helped after six months.

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