You're ignoring an infection According to New York City podiatrist William Spielfogel, DPM, people often confuse nail polish damage for a fungal infection and vice versa. "In the beginning stages of a fungal infection, the nail becomes discolored, thickened, or brittle," he says. "It's important not to self-diagnose." If you're concerned, go to the doctor and have him or her take a sample of the nail to figure out the problem -- there are oral medications, topical treatments, and lasers they can prescribe or use. And even if your nail problems are due to polish damage, be careful: A crack can lead to an infection.