Acne usually appears as a combination of some of these: (All images courtesy Dr. Jerry Tan)
Skin pores clogged with oil (sebum) and dead skin cells and topped by small black dots. The pore remains partially open at the surface.
Skin pores blocked with oil (sebum) and dead skin cells. The pore is closed over at the surface. A pale white centre can be seen.
Plugged, swollen skin pores circled by redness and filled with pus. The spots may feel tender.
Blocked skin pores with small, red, hard bumps. The spots may feel sore or sometimes rough like sandpaper.
Boil-like, red, swollen, painful, large pus-filled sacs extending deep into the skin. Some are large.
Large, often painful, solid, red bumps deep in the skin.