Persistent redness with acne often comes from a condition called post-inflammatory erythema, or PIE. This happens when acne inflammation damages small blood vessels in the skin, leaving red or pink marks even after pimples heal.
Acne starts when bacteria like Cutibacterium acnes grow in clogged pores. These bacteria break down skin oils into irritating acids and trigger immune responses. The body releases chemicals like interleukins and tumor necrosis factor that cause swelling and widen blood vessels. Even when the pimple goes away, those vessels stay dilated and show through the skin as redness.
The worse the acne inflammation, the stronger the redness lasts. In some cases, new blood vessels form, making the marks harder to fade. This is different from dark spots, which come from pigment changes. PIE is all about blood vessel issues.
Sometimes people confuse this redness with rosacea, another condition that causes ongoing facial flushing and bumps. Rosacea involves sensitive blood vessels that react to triggers like sun, heat, spicy food, alcohol, or stress. Unlike acne, rosacea does not clog pores and often includes burning or eye irritation. Both can look similar with red bumps, but acne has blackheads or whiteheads while rosacea does not.
Other factors can worsen redness during acne. Allergens like dust or pollen cause extra inflammation. Demodex mites on the skin might overgrow and add to irritation. Harsh acne treatments, such as strong retinoids or benzoyl peroxide, can irritate skin and make redness persist if misapplied.
Skin type plays a role too. Fairer skin shows redness more clearly because blood vessels are closer to the surface. People with ongoing acne flare-ups face higher chances of lasting marks.
Sources
https://www.kins-clinic.com/blogs/post-inflammatory-erythema-from-acne-a-guide-to-causes-and-treatments
https://www.westlakedermatology.com/blog/top-20-common-rosacea-triggers/
https://www.kavimd.com/rosacea-a-red-and-flushed-face
https://en.wikipedia.org/wiki/Rosacea
https://www.woodsidemd.com/post/adult-acne-or-rosacea-why-the-difference-matters-more-than-you-think
https://www.emc.id/en/care-plus/getting-to-know-rosacea-a-skin-condition-that-makes-your-face-red-easily
https://www.agelockskinclinics.com/blog/all-you-need-to-know-about-rosacea-symptoms-causes-and-treatment/
