What Causes Skin Tags and What Are They Made Of? Skin tags are small, soft growths of skin that often appear on areas of the body where skin rubs against skin or clothing, such as the neck, armpits, eyelids, or groin. Though they may seem concerning at first, skin tags are typically harmless and painless. But what exactly causes these growths, and what are they made of? What Are Skin Tags Made Of? Skin tags, also known as acrochordons, are composed primarily of collagen fibers, blood vessels, and skin cells. The core structure consists of tightly packed collagen, a protein that provides strength and elasticity to the skin. Surrounding this