Acne that does not come to a head includes deep, painful bumps like cysts and nodules. These form under the skin without pus and often last longer than regular pimples.
All acne starts the same way. Oil glands in your pores make sebum, a natural oil that keeps skin soft. Dead skin cells mix with this oil. Normally, they exit the pore easily. When the pore clogs, sebum builds up inside.
Bacteria called Cutibacterium acnes, or C. acnes, thrive in this trapped oil. Everyone has some of this bacteria on their skin. In a clogged pore, it grows fast. Your body sees it as an invader and sends white blood cells to fight it. This causes swelling and redness[1][2][4].
In regular pimples, this stays near the surface and forms a whitehead or blackhead with pus. For cysts and nodules, things go deeper. The swelling breaks the pore wall. Oil, bacteria, dead cells, and inflammatory cells spill into the skin layers below. This creates a hard, fibrous lump or a swollen cyst that stays trapped under the skin[1][2].
Hormones play a big role. Androgens, male hormones present in both men and women, boost sebum production. Levels rise during puberty, menstrual cycles, stress, or pregnancy. This extra oil clogs pores more easily[1][2].
Genetics matter too. If family members had severe acne, you have higher risk. Your skin may overreact to inflammation, making bumps worse[1].
Other factors speed it up. High sugar foods and dairy can raise insulin and hormones that increase oil. Stress releases cortisol, which does the same. Sweat, humidity, heavy makeup, or oily skincare products trap more dirt and oil in pores[1].
These bumps hurt because they press on nerves deep in the skin. They scar easily since they damage deeper layers. Unlike surface pimples, they need stronger treatments like prescriptions from a doctor[1][2].
Sources
https://londondermatologyclinics.com/cystic-acne-your-guide-to-causes-and-management/
https://www.acne.org/what-is-an-acne-nodule
https://mandayahospitalgroup.com/lumps-on-the-face-but-not-acne/
https://naturalimageskincenter.com/common-misconceptions-about-bacterial-acne-how-to-identify-it-correctly/
https://www.vinmec.com/eng/blog/differentiate-common-pimples-and-skin-cancer-en
https://www.ortho-dermatologics.com/conditions/featured-conditions/acne-vulgaris/
https://www.felixforyou.ca/blog-posts/what-is-acne
