Plantar Warts vs. Calluses: How to Tell the Difference

You notice a thick, hard spot on the bottom of your foot. It's been there for weeks, maybe months. You assume it's a callus and start filing it down — but it keeps coming back, and now it actually hurts to walk on it. Could it be something else?

Plantar warts and calluses are two of the most commonly confused foot conditions. They look similar at a glance, they both form on weight-bearing areas of the sole, and they're both made of thickened skin. But they have very different causes and need very different treatment.

What's a Callus?

A callus is your skin's protective response to repeated friction or pressure. It's thickened, hardened skin — no more, no less. Common locations include the ball of the foot, the heel, and the side of the big toe. Calluses form gradually, have smooth or slightly waxy surfaces, and don't have a distinct border. They're generally not painful unless they become very thick.

Calluses are a biomechanical signal. They form where your foot is absorbing excess pressure, which often points to an underlying issue like a bunion, hammertoe, metatarsal imbalance, or ill-fitting shoes.

What's a Plantar Wart?

A plantar wart is a viral infection. It's caused by the human papillomavirus (HPV) entering through tiny breaks in the skin — usually on the bottom of the foot. Unlike calluses, warts are living growths with their own blood supply. They can occur anywhere on the sole, spread to adjacent areas, and are contagious.

Plantar warts tend to grow inward (pushed by body weight) rather than outward, which is why they're often mistaken for calluses. But they're structurally very different.

How to Tell Them Apart

There are a few reliable ways to distinguish the two:

• The squeeze test: Pinch the spot from the sides (not pressing straight down). Calluses rarely hurt with side pressure. Warts are often sharply painful when squeezed laterally.
• Skin lines: Look closely at the surface. Calluses preserve the normal skin lines (fingerprint-like ridges) running through them. Warts disrupt the skin lines — the ridges go around the lesion, not through it.
• Black dots: Warts often have tiny dark specks visible on the surface. These are thrombosed capillaries — small blood vessels that have clotted inside the wart. Calluses never have these.
• Border: Warts have a well-defined circular border, almost like a lesion embedded in the skin. Calluses blend gradually into the surrounding skin without a sharp edge.
• Multiples: If you have several small hard spots clustered together (mosaic pattern), those are almost certainly warts. Calluses don't cluster.

Why It Matters

Treating a wart like a callus (filing it down) doesn't eliminate the virus — and can actually spread it by exposing the blood supply and transferring HPV to adjacent skin. Conversely, treating a callus with wart medication is unnecessarily harsh on normal skin.

Over-the-counter wart removers contain salicylic acid, which can work for small, superficial warts but often isn't strong enough for established plantar warts. Many patients spend months with drugstore treatments before seeking professional care, during which time the wart can spread.

How We Treat Them

Calluses are managed by addressing the underlying pressure. Debridement (carefully trimming the thickened skin) provides immediate relief, and custom orthotics redistribute weight to prevent recurrence. If a structural issue like a bunion or hammertoe is causing the callus, that can be addressed too.

Plantar warts require eliminating the virus. We offer several professional wart treatment options that are more effective than over-the-counter products, including stronger topical treatments, cryotherapy, and other modalities depending on the size and number of warts.

The Bottom Line

If it's been there for weeks, hurts when you squeeze it, or has dark specks — it's probably a wart, not a callus. And even if it is a callus, recurring calluses are your foot's way of telling you something needs to change biomechanically. Either way, a quick evaluation gives you a clear answer and a plan. Call us at (760) 728-4800 to schedule.