Blisters: Intense friction can initially cause fluid-filled blisters, which may appear yellowish if infection develops.
Fungal infections: Shoes worn by others can carry fungi that lead to athlete’s foot or nail infections. These typically cause itching, redness, peeling skin, or yellowing nails rather than a firm bump.
Why Second-Hand Shoes Are More Likely to Cause Problems
While new shoes can cause issues during the break-in period, used shoes come with extra concerns:
They’re already shaped to someone else’s feet, creating uneven pressure points.
Poor sanitation can transfer sweat, bacteria, or fungi, increasing irritation or infection risk.
(Images above typically show yellow corns or calluses caused by shoe friction.)
