Nail fungus typically starts as a small white or yellow-brown spot under the tip of a toenail or fingernail. As the infection spreads deeper, the nail thickens, changes color, and begins to crumble or break apart at the edges. It’s the most common nail disorder in adults, with up to 20% of people experiencing it at some point in their lives.
What It Looks Like in the Early Stages
The first sign is usually a discolored spot near the free edge of the nail, where the nail extends past the fingertip or toe. This spot is often white or yellowish-brown and can be easy to dismiss as a bruise or cosmetic stain. At this point the nail still feels relatively normal in thickness and texture.
Over the following weeks, that spot gradually expands. You may notice the nail becoming slightly opaque or losing its natural shine. The edge of the nail might start to look uneven or rough. These subtle changes are the best window for treatment, because the fungus hasn’t yet reached deep into the nail structure.
Color Changes as the Infection Progresses
Nail fungus doesn’t produce just one color. Depending on the type of fungus involved and how advanced the infection is, an affected nail can turn white, yellow, brown, or even green. Yellow and yellowish-brown are the most common shades. A greenish tint sometimes appears when bacteria have moved in alongside the fungus, especially in moist environments.
One particular pattern worth knowing: white superficial onychomycosis shows up as chalky white patches directly on the surface of the nail plate rather than underneath it. These patches feel rough or powdery when you run a finger across them. This type is more common on toenails and tends to stay on the outer layers of the nail, making it one of the easier forms to treat.
Thickening, Crumbling, and Shape Changes
As the fungus feeds on the protein in your nail, it triggers your body to produce extra layers of keratin underneath the nail plate. This buildup pushes the nail upward, making it noticeably thicker and sometimes difficult to trim with standard clippers. In advanced cases the nail can become so thick it presses against shoes and causes discomfort.
Along with thickening, the nail becomes brittle. Edges turn ragged and crumbly, and pieces may break off unevenly. The overall shape of the nail can warp, curving or developing ridges that weren’t there before. Chalky, yellowish debris often collects underneath the nail, visible if you look at the nail from the side or gently lift the free edge.
In the most severe stage, called total dystrophic onychomycosis, the entire nail becomes extremely thick, discolored, and misshapen. The nail may crack through the middle, and it can separate completely from the nail bed and fall off.
Separation From the Nail Bed
One of the more alarming visual signs is when the nail lifts away from the skin underneath. This usually starts at the tip or along one side and creates a gap where the nail appears hollow or has a different color than the attached portion. The detached area often looks white or yellowish because air and debris fill the space between the nail and the bed.
This separation makes the nail fragile and more vulnerable to catching on things. It also creates a warm, moist pocket that allows the fungus to spread faster. If you notice the nail pulling away from the bed, the infection has moved past the early stage.
Yeast Infections Look Different
Not all nail fungus is caused by the same organism. When yeast (typically candida) is responsible, the infection often affects the skin around the nail rather than just the nail itself. The cuticle area and the folds of skin along the sides of the nail become red, swollen, and tender to touch. A small pus-filled pocket may form near the base of the nail.
Over time, a yeast-driven infection causes the nail to grow in with ridges or a wavy texture. The nail may turn yellow or green and become dry and brittle. This type is more common on fingernails, particularly in people whose hands are frequently wet.
Nail Fungus vs. Nail Psoriasis
Psoriasis can affect nails in ways that look strikingly similar to fungus: thickening, yellow-brown discoloration, and separation from the nail bed all occur in both conditions. A few visual clues help tell them apart.
- Pitting: Nail psoriasis often creates small dents or pits in the nail surface, like tiny holes made with a pin. Fungal infections rarely cause this.
- Smell: Fungal nails frequently have a noticeable odor from the infection brewing underneath. Psoriasis does not.
- Number of nails: Psoriasis tends to affect multiple nails at once, while fungus typically starts in a single nail and spreads to others over time.
- Location: Fungus is far more common on toenails. Psoriasis is more likely to show up on fingernails.
- Other symptoms: People with nail psoriasis usually have psoriasis patches elsewhere on their body or joint pain associated with psoriatic arthritis.
If you’re unsure which condition you’re looking at, a doctor can take a small clipping or scraping from the nail and send it to a lab to confirm whether fungus is present.
What a Healing Nail Looks Like
If you’re treating nail fungus and wondering whether it’s working, the clearest sign of progress is new, healthy nail growing in from the base. The area closest to the cuticle will look pink, smooth, and clear, while the damaged portion remains discolored and thick as it slowly grows toward the tip.
This process is not fast. Because nails grow slowly, especially toenails, it typically takes 12 to 18 months for healthy growth to fully replace the damaged nail. During that time you’ll have a nail that looks half-healthy and half-infected, which is normal and expected. The key indicator is that the line between healthy and damaged nail keeps moving toward the tip rather than staying in place or retreating.