Three small structures each fail one specific way. The cuticle is a passive seal that keeps bacteria and fungus out of the growing tissue beneath the nail ¹. Rounding a toenail corner leaves a spike that grows into the skin beside it; cutting the nail shorter than the toe lets that skin roll over the edge, so new growth pushes through tissue instead of past it ². A torn hangnail is a small wound, a clean entry for the bacteria on your hand, and it can become a throbbing infected nail fold within a day or two ³.

The math favors prevention hard. Nail fungus reaches roughly 5 to 10% of adults, about 20% by age 60, and around half past 70 ⁴. Once it takes hold, the strongest treatment, oral terbinafine, fully cures only 38 to 59% of cases over 12 to 18 months, and about a quarter return within three years ⁵. Prevention costs $10 to $25 for clippers and a file.

Do it after a shower, when nails are soft and cut without splintering ⁶. Fingernails weekly, toenails every two to four weeks.

The gains stack quietly. Within weeks, nothing snags on knit fabric and no half-tear on a thumb catches all day. Within a month, toes stop registering, with no 3pm pressure point in a tight shoe. Within a year, the ingrown that used to return twice a year stays gone. Over decades, fungus climbs toward half the population past 70, and people with clean-tool habits mostly stay on the other side of that line ⁴. The gap between groomed and neglected nails at 60 is plain up close.