Acne lesions fall into two groups: non-inflammatory and inflammatory. It helps to know the difference, because they need different approaches.
Non-inflammatory lesions
These happen when excess sebum and dead skin cells build up in the follicle with little to no visible inflammation. No redness, no swelling, no pain. They show up as:
- Whiteheads (closed comedones)
- The pore is covered by a thin layer of skin, trapping oil and dead cells underneath. They look like small white or flesh-colored bumps with a pebble-like texture. Not the same thing as milia.
- Blackheads (open comedones)
- The pore is clogged but stays open at the surface. The dark color comes from the material inside the pore oxidizing when it hits air, not from dirt. This is a common misconception worth clearing up.
Non-inflammatory acne tends to be stubborn and can take a while to clear, but it responds well to consistent exfoliation and extractions.
Inflammatory lesions
These happen when a clogged follicle triggers an immune response. In that oxygen-poor, blocked environment, acne-causing bacteria can thrive, which ramps up inflammation even more. The body sends inflammatory mediators and white blood cells to the area, and that's what causes redness, swelling, tenderness, and visible pus.
Inflammatory lesions also carry a higher risk of dermal damage and scarring, which is exactly why picking or squeezing them is such a bad idea.
Microcomedones
These are the starting point behind all of this. They're microscopic follicular blockages, invisible on the surface, that form from abnormal keratinization inside the follicle. Every blackhead, whitehead, papule, pustule, and cyst starts here.
This is also the reason clearing acne takes months, not days. You're not just treating what you can see. You're preventing the microcomedones that are already forming below the surface from ever surfacing.