Why PMOS drives adult acne

If you have a PCOS diagnosis, what you have is now formally called PMOS (polyendocrine metabolic ovarian syndrome), the new name confirmed by global consensus in May 2026. The diagnostic criteria did not change. Hyperandrogenism, the elevated androgen activity that drives most of the dermatological features of PMOS, remains one of the three diagnostic criteria.

If you have had "hormonal acne" for years, tried three different cleansers, gone on and off oral contraceptives, possibly done a round of isotretinoin, and watched the acne keep returning along the jawline and chin, this article is for you. Your skin is not the problem. Your skin is where a problem is showing up.

Acne is not the inevitable result of PMOS for everyone with the diagnosis. It is more common, it shows up in a specific pattern, and it has a specific mechanism.

What PMOS-pattern acne tends to look like

Dermatology and endocrinology share a shorthand for the pattern that warrants investigating PMOS even when the person has come in about skin alone:

• Location. Jawline, chin, lower cheeks, and neck, sometimes called the "beard area." Sometimes also upper back and chest.
• Type. Deep, cystic, and often painful. Less whitehead-dominated than the surface comedonal acne of adolescence.
• Timing. Worsens in the luteal phase (roughly the week before a period) in many people, though not all.
• Persistence. Continues into the 20s, 30s, and beyond. Does not resolve with standard adolescent acne treatments.
• Response. Improves briefly with topical treatments, improves more durably with hormonal interventions that engage the upstream mechanism.

This pattern is consistent enough that some dermatologists flag it as a reason to investigate PMOS specifically, even when the patient has come in about skin alone.

The mechanism, in four steps

The acne pathway in PMOS connects directly to the androgen pathway covered in the mechanism page on why PMOS raises androgens. The first three steps below are the same; step four is the dermatological-specific extension.

Step 1: elevated insulin. Insulin resistance is present in approximately 85 percent of people with PMOS overall and approximately 75 percent at a lean body weight, per the 2026 Lancet rename consensus. The pancreas releases more insulin to compensate; insulin-like growth factor 1 (IGF-1) circulates at higher levels alongside it.

Step 2: elevated free androgens. High insulin drives ovarian theca-cell testosterone production and suppresses sex hormone-binding globulin (SHBG) production in the liver. More testosterone is biologically active and free. Testosterone gets converted in skin to dihydrotestosterone (DHT), the more potent androgen that skin tissue actually responds to. The adrenal glands contribute as a parallel source for approximately 20 to 30 percent of people with PMOS who show elevated DHEA-S.

Step 3: sebaceous gland overdrive. DHT and IGF-1 both stimulate sebaceous (oil) glands. Glands enlarge, produce more sebum, and the sebum becomes thicker and more lipid-dense than typical. This is the dermatological-specific consequence of the upstream androgen elevation.

Step 4: blocked follicles, bacteria, inflammation. Excess oil plus hyperkeratinisation (sticky dead skin cells not shedding cleanly) clogs the follicle. Bacteria, primarily Cutibacterium acnes, proliferate in the trapped oil. The immune system responds with inflammation. That inflammation is what is felt and seen as a deep, tender cystic lesion.

Why surface treatments often fail alone

Topical treatments (cleansers, retinoids, benzoyl peroxide, salicylic acid, topical antibiotics, chemical peels) act on steps 3 and 4. They can help, sometimes significantly, particularly when used consistently and in combination. They do not engage steps 1 and 2.

This is why PMOS-pattern acne often returns. The inflammation clears; the underlying driver has not changed; a new wave appears. Treating only the surface keeps the cycle running.

Surface interventions (engages steps 3 to 4): cleansers, topical retinoids (tretinoin, adapalene), benzoyl peroxide, salicylic acid, topical antibiotics, chemical peels and facials. Useful as part of a plan; incomplete on their own for PMOS-pattern acne.

Upstream interventions (engages steps 1 to 2): insulin sensitisation (lifestyle foundation interventions, metformin, inositol), anti-androgens (spironolactone), combined oral contraceptives (suppress ovarian androgen production and raise SHBG). These take longer to show effect but engage the driver.

Isotretinoin sits in its own category, working primarily by shrinking sebaceous glands. Effective for severe or resistant cases. Acne can return after a course if the upstream mechanism has not been addressed, which is part of why PMOS-pattern acne sometimes recurs after multiple isotretinoin rounds.

What the evidence supports

The interventions for PMOS-pattern acne map onto the PMOS treatment hierarchy; a few specifics relevant to skin:

Spironolactone. Blocks androgen receptors in skin. The most evidence-based hormonal approach to PMOS-pattern acne. Typical doses 50 to 100 mg daily. Takes 2 to 3 months to show meaningful improvement. Reliable contraception is required during therapy. Response rates above 70 percent at adequate dose and duration in meta-analyses.

Combined oral contraceptives. Particularly formulations with less androgenic progestins (drospirenone, desogestrel). Raise SHBG, suppress ovarian androgen production. Often combined with spironolactone for additive effect. COCs do not address insulin resistance and do not improve underlying ovulatory function once stopped; that does not make them inappropriate, only different from the foundation interventions.

Metformin and inositol. Slower to show dermatological benefit than direct anti-androgens, because they engage the upstream insulin driver. Best used as the foundation under direct skin-targeted interventions, not as standalone acne treatments. The insulin resistance pillar and the inositol evidence summary cover these in depth.

Isotretinoin. Effective for severe or resistant cases. PMOS-pattern acne can recur after a course because the upstream mechanism has not been addressed. Consider it a powerful tool for severe presentations, not a curative path for hormonally-driven acne.

If a dermatologist has offered topical treatments or isotretinoin without a conversation about hormonal contributors or PMOS labs, a reasonable question is: Are my androgens contributing to this? Would a hormonal approach be more durable? Most dermatologists welcome the question.

What about diet?

PMOS content often goes off the rails right here, so a careful answer.

High-glycaemic dietary patterns (lots of refined carbohydrates and added sugar) reliably raise insulin over time. In PMOS, that matters because of the insulin-to-androgen pathway. Dairy consumption (particularly skim milk specifically) shows a modest association with adult acne in some studies, possibly because of dairy IGF-1 content. A pattern oriented around protein, fibre, and lower-glycaemic carbohydrate sources is supported by the broader PMOS evidence base.

What the evidence does not support is single-food causation of PMOS-pattern acne, or restrictive elimination diets as standalone treatment. The principle that matters is the insulin and androgen signalling environment over time, not fear of individual foods. Restrictive dietary rules carry their own documented costs in a condition that already has elevated rates of disordered eating; the foundation framing in the PMOS treatment hierarchy addresses this explicitly.

A note on the experience

PMOS-pattern acne is among the most distressing features of the condition, not because it is medically dangerous but because of the visible weight of it. The medical system has historically treated it as cosmetic. It is not. It is an endocrine feature with an endocrine cause, downstream of a defined mechanism in a recognised condition.

Treating it that way, including asking the insulin and SHBG and DHEA-S questions covered in the androgens mechanism page, is part of taking the condition seriously, not part of vanity. If a dermatologist is managing PMOS acne in isolation, and an endocrinologist or PMOS-aware primary-care clinician is not part of the conversation, that gap is worth closing.