Acne is caused by hormones and blocked hair follicles, not by being unclean, and the NHS says so in terms worth quoting: cleaning the skin does not help to remove the blockage. There is also no evidence that poor hygiene plays a role at all.

That matters because the instinctive response, washing harder and more often, treats a cause that is not there while irritating skin that is already inflamed. The treatments that work act on the actual mechanism, and they take months rather than days.

Key takeaways

  • It is extremely common. About 95% of people aged 11 to 30 are affected to some extent.
  • Hygiene is not the cause. There is no evidence that poor hygiene plays a role, and cleaning does not remove the blockage.
  • The mechanism is hormonal. Hormones drive excess sebum and thicken the follicle lining, blocking the pore.
  • Treatments take several months. Do not expect results overnight, and once they work the results are usually good.
  • Do not pick or squeeze. This can lead to permanent scarring.
  • Moderate or severe acne needs a doctor, and so do nodules or cysts, because they need proper treatment to avoid scarring.
  • It usually improves with age, often clearing by the mid-20s, though about 3% of adults over 35 still have it.

What actually causes acne?

Hormones acting on the oil glands and on the lining of the hair follicle.

The NHS sets out the chain clearly. Certain hormones cause the grease-producing glands next to hair follicles to produce larger amounts of oil, called abnormal sebum. That sebum changes the behaviour of P. acnes, a usually harmless skin bacterium, which becomes more aggressive and causes inflammation and pus. The same hormones thicken the inner lining of the hair follicle, blocking the pore.

Two consequences follow, and both contradict common advice:

  • Cleaning the skin does not remove that blockage. It is inside the follicle, not on the surface.
  • Poor hygiene is not a cause. The NHS states there is no evidence that poor hygiene or sexual activity play a role.

Acne is also known to run in families. If both parents had acne, you are likely to as well. And hormonal changes during the menstrual cycle or pregnancy can trigger episodes in women, which is why adult acne in women often follows a monthly pattern.

Who gets it, and does it go away?

Most people, and usually yes.

About 95% of people aged 11 to 30 are affected to some extent. It is most common in girls from 14 to 17 and boys from 16 to 19. Most people have it on and off for several years before it improves, and it often disappears by the mid-20s.

The exception worth naming: in some cases it continues into adult life, and about 3% of adults over 35 have acne. Adult acne is not a failure to grow out of a teenage problem, and it is treated on the same principles.

What are the treatments?

Topical treatments first, then oral options, escalating with severity.

Topical retinoids such as adapalene and tretinoin act on the follicle blockage itself, which is the part washing cannot reach. They commonly cause irritation and dryness in the first weeks, and they increase sun sensitivity, which matters in a bright climate.

Benzoyl peroxide reduces bacteria and helps unblock pores. It bleaches fabric, so towels and pillowcases are worth thinking about.

Azelaic acid is an alternative for people who cannot tolerate retinoids or benzoyl peroxide, and is often used where post-inflammatory pigmentation is a concern.

Topical antibiotics such as clindamycin are used for inflamed acne, generally combined with benzoyl peroxide rather than alone, to limit resistance.

Oral antibiotics such as doxycycline are used for moderate acne over months rather than days. Doxycycline carries its own practical rules, including a notable sun-sensitivity warning, covered in doxycycline.

Hormonal treatment is an option for some women, where the monthly pattern points at the driver.

Isotretinoin is the treatment for severe acne that has not responded to other options. It is prescribed and monitored by a specialist, and it carries strict requirements around pregnancy, because it causes serious birth defects. Anyone considering it needs that conversation in full with the prescriber rather than a summary here.

Why is it taking so long to work?

Because the treatments act on how follicles behave, and that changes slowly.

The NHS is direct: treatments can take several months to work, so do not expect results overnight, and once they do start working the results are usually good.

This is the single commonest reason acne treatment fails. People stop at four weeks, conclude the product did nothing, and switch, restarting the clock. Some treatments also cause an initial worsening before improvement.

Two practical rules follow. Give a treatment the time your prescriber specified before judging it. And change one thing at a time, because stacking three new products makes it impossible to tell which helped and which caused the irritation.

When should I see a doctor?

For moderate or severe acne, for nodules or cysts, or when it is affecting how you feel.

The NHS gives three triggers:

  • if over-the-counter treatments do not control it
  • if it is making you feel very unhappy
  • if you have moderate or severe acne, or develop nodules or cysts, because these need proper treatment to avoid scarring

That third one is the time-sensitive one. Scarring is far easier to prevent than to treat, so deep, painful lumps are a reason to act rather than wait.

The second is stated by the NHS as a reason in its own right. Acne’s effect on confidence is a legitimate ground for treatment, not vanity.

What about scarring and marks?

Do not pick, and know the difference between a mark and a scar.

The NHS is explicit: resist the temptation to pick or squeeze spots, as this can lead to permanent scarring.

Two different things get called scars:

  • Post-inflammatory marks, flat brown or red patches left after a spot heals. These are pigment changes, they fade over months, and sun exposure makes them darker and slower to go. On brown and darker skin they are often the more distressing problem. Sun protection genuinely helps here, and the same principles as melasma apply.
  • True scars, where the skin texture has changed. These do not fade on their own and are treated separately.

Preventing both means treating the acne properly and early, and leaving spots alone.

Do and don’t

Do:

  • Treat the follicle, not the surface, with a treatment aimed at the cause.
  • Give treatment several months before judging it.
  • Change one product at a time.
  • Use sun protection, especially on retinoids or doxycycline.
  • See a doctor for nodules, cysts, or acne that is affecting you.

Don’t:

  • Don’t wash more often or harder; it does not clear the blockage.
  • Don’t pick or squeeze spots.
  • Don’t stop a treatment at four weeks and assume it failed.
  • Don’t combine several new actives at once.
  • Don’t take isotretinoin without specialist supervision.

Frequently asked questions

Does diet cause acne? The mechanism the NHS describes is hormonal, involving sebum and follicle blockage, and it names family history and hormonal changes as contributors. If a particular food reliably worsens yours, that is worth noting, but diet is not the established cause and restricting it is not a substitute for treatment.

Will washing more often help? No. The blockage is inside the follicle and the NHS states that cleaning the skin does not remove it. Over-washing tends to irritate skin already inflamed.

Is adult acne different? It has the same mechanism, and about 3% of adults over 35 have acne. In women it often follows the menstrual cycle, which can point towards a hormonal approach.

Where to go next

The skin care category lists what is stocked here, and acne vulgaris approaches it from the diagnosis. If you are dealing with the marks left behind rather than active spots, melasma covers pigmentation and sun protection.

MedicForce option: our skin listings show active ingredient and strength, which matters for acne treatments sold at several concentrations.

  • Acne, NHS causes, who is affected, why cleaning does not clear the blockage, when to see a GP, and treatment expectations.