Unfortunately, the damage does not end there. Once bacteria enter the follicles, the immune system, which protects the body from infection and disease, reacts. Blood, rich with infection-fighting white blood cells, rushes to the area. As the infection worsens, pus and  other powerful chemicals are also produced to combat the infection. This causes the infected area to become hot, red, swollen, and painful.

Heat, redness, swelling, pain, and the presence of pus are all characteristics of inflammation, which in the case of acne appears on the skin in the form of papules, pustules, and cysts, other types of acne lesions.