Acne basics: how it forms, common myths and when to seek help

Acne is so common that it is easy to dismiss, and so visible that it rarely feels minor to the person who has it. People often wonder whether they caused it by what they eat or by not washing enough, and whether it is worth seeing a doctor. This page explains how acne forms, who gets it, what major sources say about popular myths, the categories of treatment that clinicians describe, and the situations in which named bodies suggest professional advice. It is general education, not a diagnosis.

How acne forms

The process starts in the hair follicle, the tiny canal in the skin from which a hair grows. According to the National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS), sebum (the skin's natural oil) and dead skin cells plug the follicle. Bacteria that normally live on the skin then grow in the plugged follicle and cause inflammation. When the follicle wall breaks down, its contents spill into nearby skin and form pimples or other lesions.

The NHS describes the resulting spots in plain terms: whiteheads, blackheads, papules (raised red or pink bumps), pustules (bumps filled with pus), and nodules or cysts, which are larger, sometimes painful lumps under the skin. Acne usually affects the face, chest and back, and ranges from a few mild spots to deep, painful lumps. Hormone changes, including those at puberty, during periods, menopause and pregnancy, can contribute, as can conditions such as polycystic ovary syndrome (PCOS), certain medicines and greasy skin or hair products, according to the NHS.

Who gets acne

NIAMS calls acne a common skin condition and says it is most common in teenagers and young adults, more often in males during the teenage years and in women in adulthood. For most people it clears by their thirties, though some continue to have it in their forties and fifties. Neither NIAMS nor the NHS pages used here give a precise prevalence figure, and numbers quoted elsewhere vary with how acne is defined, so this page leaves them out.

Acne is not limited to teenagers. Adult acne is real, and the NHS notes that it can also affect mental health, causing anxiety, depression and low self-esteem. That impact is a legitimate reason to seek help, whatever the age.

Diet: what sources say

Few acne topics generate as much confident advice as food. The American Academy of Dermatology is careful. It says that foods that cause blood sugar to rise quickly, such as white bread and fries, may worsen acne, but that the evidence is limited and more research is needed to know for sure. It also cites small studies suggesting that a low-glycemic diet, which cuts back on fast-spiking carbohydrates, may reduce the amount of acne.

On dairy, the Academy says some studies link cow's milk to acne but that why it may increase or worsen acne is still a bit of a mystery. It adds that no studies have found that products made from milk, such as yogurt or cheese, lead to more breakouts. NIAMS puts it briefly: some studies show that eating certain foods may make acne worse, and researchers are still studying the role of diet.

The fair summary is that diet may matter for some people, that the evidence is still developing, and that no sweeping rule is supported. Cutting out whole food groups on the strength of an online claim is something to discuss with a doctor first, especially for growing teenagers.

Washing and skin care: what sources say

A common belief is that acne comes from dirty skin and that more scrubbing helps. The sources point the other way on scrubbing. NIAMS lists scrubbing the skin too hard, and squeezing or picking at blemishes, among the things that may worsen acne. The NHS advises washing twice a day with a gentle cleanser, avoiding scrubbing, which can irritate the skin, removing make-up daily and not picking or squeezing spots.

NIAMS offers similar washing tips: a mild cleanser in the morning and evening and after heavy exercise, avoiding strong soaps, astringents and rough scrub pads, rinsing with lukewarm water, and shampooing regularly if the hair is oily. Acne begins inside the follicle, so washing alone is not described as a cure.

Treatment categories

Clinicians group acne treatments by how they act. The American Academy of Dermatology describes three broad groups, and NIAMS lists much the same ones. This is a description of the field, not guidance on what any person should use.

• Topical medicines applied to the skin, such as retinoids (vitamin A derivatives), benzoyl peroxide, topical antibiotics, salicylic acid and azelaic acid.
• Medicines that work throughout the body, which the Academy lists as oral antibiotics, combined birth control pills, spironolactone (for women) and isotretinoin for severe nodular acne.
• In-office procedures, including corticosteroid injections into large painful breakouts, chemical peels, laser or light therapy and acne extraction by a trained doctor.

Each category comes with its own cautions. The Academy notes, for example, that people who smoke, have heart disease or are pregnant or planning pregnancy should tell their dermatologist before starting a birth control pill. NIAMS notes that benzoyl peroxide is available over the counter.

Scarring and discolouration

This is the part many people underestimate. The American Academy of Dermatology names preventing acne scars as one of the three goals of treatment, and says nodular acne, the most severe type, can leave scars. The NHS notes that acne can leave scars including shallow holes in the skin, and that picking or squeezing spots increases the risk.

NIAMS adds that people of colour may develop skin discolouration after acne heals, and that sunscreen helps treat and prevent dark spots. For scars that are already present, NIAMS lists procedures such as laser or light therapy, chemical peels, scar fillers, tiny-needle treatments, corticosteroid injections and surgery, usually considered when severe acne or scarring does not respond to medication. Which of these suits a person depends on the type of scar, which is something a specialist judges in person.

When acne is a reason to see a clinician

The NHS suggests seeking advice if self-treatment is not working, if spots are numerous, deep, painful or scarring, if there are signs of skin infection, or if acne affects your mental health. NIAMS likewise says to see a doctor to discuss medication side effects, when acne causes embarrassment or anxiety, and when severe acne or scarring does not respond to topical or oral medicines. It adds that dermatologists or primary care providers can diagnose and treat acne.

The American Academy of Dermatology points to another reason: other conditions can look like acne, including hidradenitis suppurativa, perioral dermatitis and folliculitis. Telling them apart is part of how dermatologists diagnose skin conditions. If an appointment is planned, preparing for a dermatology visit covers what to bring. Scars and marks left behind are discussed from a different angle in wound and scar care alongside physical therapy.

NIAMS describes the assessment itself as fairly simple: a provider asks about family history, menstrual cycles (for girls and women), symptoms and how long acne has been present, and any current or recent medications, examines the skin, and may order lab work to check for other conditions.

Honest limits

Acne is well studied, yet several questions remain open. How much diet matters, and which foods, is still being researched. Responses to treatment differ between people and often take time. Public bodies in different countries phrase their advice differently and vary in which medicines are available over the counter, so what is typical in one place may not apply in another.

This page has not been medically reviewed and cannot assess your skin. Individual care varies, and your own doctor or specialist has the final word.

The short version

Acne starts when oil and dead skin plug hair follicles and bacteria-driven inflammation follows. Diet may play a role for some people, but evidence is still limited, and gentle washing is favoured over hard scrubbing. Treatments fall into topical, whole-body and procedure-based groups, and because acne can scar and affect wellbeing, persistent or severe cases are a good reason to see a clinician.