Acne

Acne is rarely a single-cause condition. Four mechanisms operate in parallel inside every active lesion, and they reinforce one another. Targeting only one (the mistake behind most failed routines) leaves the remaining three to keep the cycle going. Each mechanism below sits in a published clinical pathway with decades of evidence behind it.

Sebum overproduction and follicular keratinization

The pilosebaceous unit produces sebum continuously. Androgen hormones (testosterone and its more potent metabolite dihydrotestosterone) drive sebaceous gland output, which is why acne tracks puberty and menstrual cycles. The same hormonal signal accelerates the rate at which keratinocytes line the follicle, and these cells fail to shed normally. The dysregulation is local: sebaceous glands carry their own 5-alpha-reductase enzyme, so even normal circulating androgen levels can produce hyperactive sebum output if the gland is unusually sensitive.

The result is a microcomedone: a microscopic plug of sebum and corneocytes wedged in the follicular opening. Microcomedones are invisible at the surface but form weeks before any visible blemish appears. Sebum composition itself shifts in acne-prone skin (squalene oxidises faster, ceramide content drops, and free fatty acid ratios rise), making the lipid mix more comedogenic. Topical retinoids and salicylic acid both target this step. Salicylic acid is lipid-soluble, penetrates the sebum-rich follicle, and dissolves the corneocyte bonds that hold the plug together. Niacinamide regulates sebum output and reduces follicular keratinization in parallel, with controlled studies showing roughly a 30% reduction in casual sebum levels after four weeks of consistent use.

Cutibacterium acnes and the inflammatory cascade

Cutibacterium acnes is a normal resident of healthy skin. It becomes a problem only when the follicular environment shifts: a sealed, anaerobic, sebum-rich pocket is its ideal niche. Inside the plugged follicle, C. acnes proliferates and releases lipases that hydrolyse sebum triglycerides into free fatty acids, porphyrins that generate reactive oxygen species, and pro-inflammatory peptides. Recent strain-level research shows that some C. acnes ribotypes are strongly associated with acne while others are commensal in clear skin. Bacterial diversity, not bacterial presence, is the relevant variable.

These molecules activate Toll-like receptor 2 on local immune cells and trigger interleukin-1, IL-8, and TNF-alpha release. The follicle wall ruptures into the surrounding dermis, releasing keratin and bacteria into tissue. That rupture, not bacteria alone, produces the visible papule, pustule, or nodule. This is why C. acnes-targeting action without redness-soothing action falls short. A modern routine pairs both: C. acnes targeting through Salicylic Acid and Tea Tree Oil, and redness modulation through Niacinamide and Zinc PCA. The dual approach also explains why oral antibiotics alone often fall short long-term — they suppress bacteria but do not address the underlying follicular plugging or the redness profile of the lesion bed.

Post-inflammatory pigmentation and barrier disruption

Once a lesion resolves, the work is not over for skin tones IV through VI. The same inflammatory signal that produced the papule also activated melanocytes in the lesion bed. The result is a brown or violet mark that can persist for three to twelve months: post-inflammatory hyperpigmentation, or PIH.

PIH affects roughly 65% of acne sufferers with Fitzpatrick III–V skin tones and is the single most cited reason many patients describe acne as scarring even when no true scar tissue forms. Niacinamide, alpha-arbutin, and tranexamic acid each suppress tyrosinase and reduce melanin transfer, which is why BIOSAR formulations for blemish-prone skin pair active acid systems with pigment-fading actives. Daily broad-spectrum SPF is non-negotiable: UV exposure deepens existing PIH and slows fade time.

Barrier disruption is the parallel concern. Aggressive cleansers, alcohol-based toners, and over-application of actives strip the lipid barrier and trigger compensatory sebum production: the paradox where harsher routines worsen oil. The clinical correction is counterintuitive: gentler cleansing, fewer actives at the same time, and consistent ceramide-rich moisturisation. Healthy barrier function is a prerequisite for tolerating salicylic acid and retinoids long enough to see full results, which take eight to twelve weeks of consistent use. Avoid retinoids during pregnancy and breastfeeding.