Several factors contribute to the start of an acne lesion:
- Corneocytes, or skin cells, become more "sticky" as they are shed and accumulate in the pore instead of flowing out onto the skin.
- More skin cells are shed at the top of the pore than the bottom.
- Sebum production is increased.
During this stage, the pore looks normal on the outside but there are distinct changes in the cells surrounding the pore. As the material in the pore builds up, it creates a bottleneck that prevents sloughing. The medical term for this stage is a microcomedone.
The bacteria Propionibacterium acnes, often shortened to P. acnes, normally resides in the pores. It uses sebum as a nutrient for growth. As sebum production increases, the number of P. acnes bacteria increases in the pore. In the microcomedone stage, the bacteria do not cause infection because they are only in the material inside the pore, not infecting the skin.
Medications that help at this stage include:
- Over-the-counter benzoyl peroxide kills bacteria and helps prevent P. acnes from overgrowing.
- Prescription tretinoin products like Retin-A, Retin-A Micro, and Avita reverse the "stickiness" of the skin cells, allowing them to slough normally.
- Over-the-counter salicylic acid 2% lotion is a beta hydroxy acid that also reverses the "stickiness" of the skin cells.