Acne, explained
What acne is, why it happens, and what actually helps
A plain explanation of acne, from what happens inside a pore to which treatments have the strongest evidence. Every claim is linked to its source.
Drafted with AI assistance · not reviewed by a dermatologist · Last updated October 5, 2026 · 8 min read
What acne is
Acne is a long-lasting inflammatory condition of the hair follicles and the small oil glands attached to them. It appears where those glands are busiest, on the face, neck, chest and back, and it ranges from a few spots to deep, painful lumps under the skin.[1][8]
It is one of the most common conditions in the world. A 2015 review estimated that acne affects 9.4 percent of the world's population, which makes it the eighth most common disease worldwide. It is most common in teenagers after puberty, and boys are more often affected by the severe forms.[2] It does not always end with adolescence: acne can continue into adulthood.[1]
Why spots form
Researchers describe four processes that work together.[1] Hormones called androgens make the oil glands produce more sebum, the skin's natural oil. The skin cells lining the follicle shed abnormally and stick together, so oil and dead cells clog the opening. Bacteria that normally live on the skin, Cutibacterium acnes (formerly Propionibacterium acnes), multiply in the blocked follicle. Then the area becomes inflamed, which is what turns a clogged pore into a red, sore spot.
Changes in hormone levels are a common trigger, which is why acne often starts at puberty and can flare around periods, pregnancy or menopause. Some medicines, and skin or hair products that leave the skin greasy, can also play a part.[8] What sets the process off in one person and not another is still not fully understood.[1]
The kinds of spots
Most people with acne have more than one kind of spot at the same time.[8] The kinds follow the stages above. Whiteheads are small, skin-colored bumps, and blackheads are dark spots that are usually flat; both are clogged follicles. Papules are raised bumps, which look pink or red on white skin and brown or purple on brown and black skin. Pustules are raised bumps filled with pus. Nodules and cysts are larger lumps deeper under the skin; they can join together and are often painful.[8]
What treatment has the best evidence
The most thorough recent review of acne treatment is the American Academy of Dermatology's 2024 guideline, which graded each treatment by the strength of the evidence behind it.[3] It made strong recommendations for benzoyl peroxide, topical retinoids such as adapalene, topical antibiotics and the oral antibiotic doxycycline. It strongly recommends oral isotretinoin for acne that is severe, is causing scarring or real distress, or has not responded to other treatment.[3]
It made weaker, conditional recommendations for azelaic acid, salicylic acid, topical clascoterone, the oral antibiotics minocycline and sarecycline, combined oral contraceptive pills and spironolactone. It also advises combining topical treatments that work in different ways and keeping oral antibiotics limited, paired with a topical treatment when they are used.[3]
Strong recommendation
- Benzoyl peroxide
- Topical retinoids (such as adapalene)
- Topical antibiotics
- Oral doxycycline
- Oral isotretinoin, for severe or scarring acne, or acne that has not responded
Conditional recommendation
- Azelaic acid
- Salicylic acid
- Topical clascoterone
- Oral minocycline or sarecycline
- Combined oral contraceptive pills
- Spironolactone
Good practice
- Combining topical treatments that work in different ways
- Limiting oral antibiotics, and pairing them with a topical treatment
- Steroid injections for larger lesions
Some of these, including benzoyl peroxide and salicylic acid, can be bought without a prescription, and a pharmacist can help choose one; many of the others need a doctor.[8] No single treatment suits everyone, but a review in The Lancet notes that a regimen that reduces spots can be found for most people.[1]
What about diet?
Diet is the question people ask most, and the honest answer is that it is unsettled. The Lancet review described diet as implicated but not proven.[1]
Two small trials in young men with acne-prone skin found more spots after pure cocoa or very dark chocolate: 14 men over one week in one, 25 men over four weeks in the other.[4][5] In a 12-week trial, 43 young men on a low-glycemic-load diet saw spot counts fall further than those on their usual diet, though the diet group also lost weight, which makes the result harder to read.[6] And an analysis that pooled observational studies found that people who drank more milk were more likely to have acne, while yogurt and cheese showed no link; studies of that kind can show an association, not a cause.[7]
| Question | What the research found | How settled |
|---|---|---|
| Do benzoyl peroxide and topical retinoids work? | The 2024 AAD guideline makes strong recommendations for both, its highest grade.[3] | Well established |
| Does chocolate cause acne? | Two small trials in young men found more spots after pure cocoa or very dark chocolate; neither had more than 25 people.[4][5] | Still argued about |
| Does a high-sugar diet matter? | In a 12-week trial of 43 young men, spot counts fell further on a low-glycemic-load diet than on the usual diet. One small trial, men only.[6] | Still argued about |
| Does milk matter? | Pooled observational studies link higher milk intake with acne; yogurt and cheese showed no link. Observational data cannot show cause.[7] | Still argued about |
| Is diet the cause of acne? | A Lancet review calls diet implicated but not proven, and says exactly what triggers acne is still unclear.[1] | Thin evidence |
For most people, that makes a diet change a reasonable thing to try for yourself, not a replacement for treatments with much stronger evidence behind them.
Scarring, and when to see a doctor
Acne can leave marks and scars, including shallow pits in the skin.[8] The Lancet review puts facial scarring from acne at up to 20 percent of teenagers.[1] Picking or squeezing spots can cause scars, and scrubbing the skin can irritate it and make acne worse.[8]
It is worth seeing a doctor if treating acne yourself has not helped; if you have many spots, or deep, painful or scarring ones; if the skin looks infected, hot, swollen and red; or if acne is affecting your mental health.[8] Acne can affect self-esteem, and anxiety and low mood are recognized effects of the condition.[1][8] Asking for help early is not an overreaction.
How to read this site
Every article on Acne Cut names its sources, shows when it was last updated, and carries one of four labels for how settled the evidence is: Well established Still argued about Thin evidence Mostly marketing. The labels describe the research, not how likely something is to work for you. Articles are drafted with AI assistance and checked against a fixed editorial standard; they are not reviewed by a dermatologist. Read the editorial policy.
Sources
- Williams HC, Dellavalle RP, Garner S. Acne vulgaris. Lancet. 2012;379(9813):361–372. PubMed 21880356
- Tan JK, Bhate K. A global perspective on the epidemiology of acne. Br J Dermatol. 2015;172 Suppl 1:3–12. PubMed 25597339
- Reynolds RV, Yeung H, Cheng CE, et al. Guidelines of care for the management of acne vulgaris. J Am Acad Dermatol. 2024;90(5):1006.e1–1006.e30. PubMed 38300170
- Caperton C, Block S, Viera M, Keri J, Berman B. Double-blind, placebo-controlled study assessing the effect of chocolate consumption in subjects with a history of acne vulgaris. J Clin Aesthet Dermatol. 2014;7(5):19–23. PubMed 24847404
- Vongraviopap S, Asawanonda P. Dark chocolate exacerbates acne. Int J Dermatol. 2016;55(5):587–591. PubMed 26711092
- Smith RN, Mann NJ, Braue A, Mäkeläinen H, Varigos GA. A low-glycemic-load diet improves symptoms in acne vulgaris patients: a randomized controlled trial. Am J Clin Nutr. 2007;86(1):107–115. PubMed 17616769
- Aghasi M, Golzarand M, Shab-Bidar S, et al. Dairy intake and acne development: a meta-analysis of observational studies. Clin Nutr. 2019;38(3):1067–1075. PubMed 29778512
- NHS. Acne. nhs.uk/conditions/acne. Page last reviewed 22 September 2026; accessed 5 October 2026. Read it
