Acne: Causes, Scarring & When to See a Doctor

Acne starts when hair follicles become blocked. The sebaceous glands attached to each follicle begin producing too much sebum (oil), which mixes with dead skin cells to form a plug. Normally harmless bacteria that live on the skin can then infect the blocked follicle, producing the redness and inflammation of papules, pustules, nodules or cysts.

Hormones drive a lot of this. Teenage acne is thought to be triggered by rising testosterone during puberty. In adults, acne is more common in women, and is often linked to hormonal changes around periods, pregnancy or conditions such as polycystic ovary syndrome (PCOS).

Genetics plays a real part too (acne can run in families) and oily skincare or hair products, greasy moisturisers, stress and certain medications can all make it worse.

Acne is a genuine medical condition, and the NHS treats it through a defined, funded stepped pathway: topical treatments first (benzoyl peroxide, a topical retinoid, or azelaic acid if the others irritate your skin), then oral antibiotics for moderate-to-severe acne, then (for women) the combined contraceptive pill, then referral to a dermatology team for a large number of spots on the chest and back, painful nodules, a real risk of scarring, or significant psychological impact, and isotretinoin as a specialist last resort. If any of that describes you, your GP is the right and honest place to start, not a private cosmetic clinic.

Isotretinoin cannot simply be prescribed by a GP. It is a specialist-only medicine. Under current British Association of Dermatologists guidance, only a Consultant Dermatologist can act as the “Lead Prescriber” who decides to start it, or, within some services, a GP who is nationally accredited with an Extended Role or Special Interest and is working inside a pathway a consultant dermatologist has personally set up and continues to govern. There is no route by which a routine GP appointment leads straight to an isotretinoin prescription. Severe acne that may need it should go through NHS dermatology referral, never a private aesthetic clinic.

Don’t squeeze. Both the NHS and the British Association of Dermatologists advise against trying to “clean out” blackheads or squeeze spots: doing so can make acne worse and cause permanent scarring.

The psychological side is real, and is itself a reason to see a GP. A 2023 systematic review pooling nearly 7,800 participants found significantly higher rates of depression, anxiety and perceived stress among people with acne compared with people without it. If acne is affecting your mood or confidence, that alone is one of the NHS’s own criteria for referral.

Acne scarring

Scarring is the one part of this picture where private, cosmetic treatment plays an honest role because scar-revision treatments such as laser resurfacing and microneedling are not routinely available on the NHS. There are several recognised types: ice-pick scars (narrow, deep, and the most common, at 60–70% of cases), boxcar scars (wider, punched-out depressions), rolling scars (broad, with a sloping edge), and, less often, raised hypertrophic or keloid scarring. Scars form mainly because ongoing inflammation from active acne damages collagen in the deeper skin, which is also why treating active acne promptly, rather than waiting it out, helps limit how much scarring is left behind.

The evidence for scar treatments is genuinely mixed in quality. The strongest data found for microneedling combined with platelet-rich plasma (PRP) shows a real, statistically significant benefit over microneedling alone, but comes mostly from smaller, non-randomised, split-face studies rather than large controlled trials, and most people need more than one session for a worthwhile improvement.