Acne

Acne (acne vulgaris) is a common, long-term skin condition that develops when hair follicles become clogged with oil and dead skin cells, producing whiteheads, blackheads, pimples, and sometimes deeper nodules — most often on the face, chest, and back. It is not caused by poor hygiene, and for most people it is highly treatable once the right combination of therapies is found.

What is acne?

Acne is a disorder of the *pilosebaceous unit* — the tiny structure made up of a hair follicle and its attached oil (sebaceous) gland. When that unit becomes plugged and inflamed, the visible lesions of acne appear. It is the most common skin condition seen in clinical practice and one of the most prevalent skin diseases worldwide; Global Burden of Disease data consistently rank it among the most common skin disorders, and a systematic review of the epidemiology of acne reported adolescent prevalence estimates spanning a wide range, with most studies clustering around 35% to over 90% depending on age and how acne was defined (NIH/StatPearls; Heng & Chew, Nature *Scientific Reports* systematic review, 2020).

The medical name is acne vulgaris (ICD-10 code L70.0, which itself includes cystic, nodular, and pustular forms), with separate codes for distinct variants such as acne conglobata (L70.1) and infantile acne (L70.4). Acne exists on a spectrum, from a few occasional comedones ("clogged pores") to widespread inflammatory disease that can leave permanent scars.

Acne is most associated with the teenage years, but it is genuinely a condition of all ages. It can begin before puberty (preadolescent acne, sometimes as early as ages 7–12) and frequently persists into — or even first appears during — adulthood, particularly in women (NIH/StatPearls).

What causes acne and who is at risk?

Acne develops through four interacting mechanisms within the pilosebaceous unit (NIH/StatPearls; AAD):

1. Excess sebum (oil) production, driven largely by androgen hormones.
2. Follicular hyperkeratinization — sticky dead skin cells plug the pore, forming a microcomedone, the precursor to all acne lesions.
3. Bacteria — *Cutibacterium acnes* (formerly *Propionibacterium acnes*), a normal skin organism, proliferates in the clogged, oily follicle.
4. Inflammation — the immune system reacts to the trapped material and bacteria, producing redness, swelling, and pus.

Common risk factors and contributors

• Hormones. Androgens (such as testosterone) enlarge sebaceous glands and increase oil output, which is why acne typically begins around puberty. Hormonal fluctuations around menstruation, pregnancy, and conditions like polycystic ovary syndrome (PCOS) can worsen it.
• Family history. Acne has a strong genetic component; having close relatives with acne raises individual risk.
• Medications. Corticosteroids, anabolic steroids, lithium, some anticonvulsants, and certain hormonal agents can trigger or aggravate acne (drug-induced acne).
• Mechanical and occlusive factors. Friction or pressure from helmets, straps, tight clothing, or phones ("acne mechanica"), and pore-clogging (comedogenic) cosmetics or hair products.
• Diet. Evidence is still evolving, but high–glycemic-index diets and, in some studies, skim milk have been associated with acne. Chocolate and greasy food are not established causes (AAD).
• Stress can aggravate existing acne, though it does not directly cause it.

Importantly, acne is not caused by dirty skin, and over-washing or scrubbing can make it worse by irritating the skin barrier.

What are the symptoms of acne?

Acne lesions fall into two broad categories — non-inflammatory and inflammatory — and most people have a mix. Lesions appear where sebaceous glands are densest: the face, forehead, chest, upper back, and shoulders.

Non-inflammatory lesions (comedones)

• Blackheads (open comedones): plugged pores open to the surface; the dark color is oxidized debris, not dirt.
• Whiteheads (closed comedones): plugged pores covered by skin, appearing as small, skin-colored or whitish bumps.

Inflammatory lesions

• Papules: small, red, tender bumps.
• Pustules ("pimples"): papules topped with visible pus.
• Nodules: large, firm, painful lumps deep under the skin.
• Cysts: deep, pus-filled, painful lesions; nodulocystic acne carries the highest risk of scarring.

Acne is graded by severity (NIH/StatPearls):

• Mild: mostly comedones with few inflammatory papules or pustules, no scarring.
• Moderate: more numerous papules and pustules, possibly a few nodules.
• Severe: widespread inflammatory lesions, nodules and cysts, often with scarring.

Beyond the visible lesions, acne can cause post-inflammatory hyperpigmentation (dark marks, especially in skin of color) or post-inflammatory erythema (lingering redness), as well as permanent scarring (ice-pick, boxcar, and rolling scars). Acne also has a well-documented impact on mental health, including anxiety, depression, and reduced self-esteem (NIH/StatPearls; AAD).

How is acne diagnosed?

Acne is a clinical diagnosis — a clinician examines the skin and identifies the characteristic lesions and their distribution. No blood test or imaging is needed in typical cases (NIH/StatPearls).

During evaluation, a clinician will usually:

• Assess lesion types (comedonal vs. inflammatory vs. nodulocystic) and distribution.
• Grade severity (mild/moderate/severe) to guide treatment.
• Look for scarring or pigmentation that may need targeted treatment.
• Review triggers — medications, skincare/cosmetic products, and menstrual or hormonal patterns.

When are tests ordered?

Laboratory testing is reserved for specific situations rather than routine acne. Workup for hyperandrogenism may be considered when a woman has acne accompanied by signs such as irregular periods, excess facial/body hair (hirsutism), or sudden, severe, or treatment-resistant acne — pointing toward PCOS or another endocrine cause. In that setting, clinicians may check hormone levels such as total and free testosterone, DHEA-S, and LH/FSH, often timed to the menstrual cycle (NIH/StatPearls; supported by Endocrine Society guidance on hyperandrogenism). Sudden, explosive acne can rarely signal a more serious variant (acne fulminans) that warrants prompt specialist evaluation.

A few conditions can mimic acne, including rosacea, perioral dermatitis, folliculitis, and keratosis pilaris; the clinical exam usually distinguishes them.

How is acne treated?

Treatment is tailored to severity, lesion type, skin type, and patient preference, and almost always combines mechanisms rather than relying on a single agent. The 2024 American Academy of Dermatology (AAD) guidelines emphasize multimodal therapy — pairing agents with different mechanisms to improve results and limit antibiotic resistance (AAD 2024 guidelines, *JAAD*).

1. Skincare and lifestyle first

• Wash affected areas gently twice daily with a mild cleanser; avoid harsh scrubbing.
• Use non-comedogenic, oil-free moisturizers, sunscreen, and cosmetics.
• Do not pick or squeeze lesions, which increases inflammation and scarring.
• Be patient: most regimens take 6–8 weeks or longer to show meaningful improvement.

2. Over-the-counter (OTC) options

• Benzoyl peroxide — antibacterial and mildly comedolytic; a cornerstone OTC and prescription agent. The AAD makes a strong recommendation for benzoyl peroxide, and it is often paired with antibiotics to reduce bacterial resistance (AAD 2024).
• Salicylic acid — a beta-hydroxy acid that helps unplug pores; useful for comedonal acne.
• Adapalene — a topical retinoid now available OTC, effective for comedonal and mild inflammatory acne.
• Azelaic acid — helps with both lesions and post-inflammatory pigmentation.

3. Prescription topicals

• Topical retinoids (adapalene, tretinoin, tazarotene, trifarotene) — the AAD strongly recommends topical retinoids; they normalize keratinization, clear comedones, and serve as both first-line and maintenance therapy.
• Topical antibiotics (clindamycin, erythromycin) — reduce bacteria and inflammation, but should not be used alone; they are combined with benzoyl peroxide to limit resistance.
• Fixed-dose combinations — the AAD recommends combination products such as a topical retinoid plus antibiotic, or an antibiotic plus benzoyl peroxide.
• Topical clascoterone — a newer topical anti-androgen for inflammatory and comedonal acne in adolescents and adults (AAD 2024).
• Topical dapsone — an anti-inflammatory option, sometimes used in adult women.

4. Oral (systemic) prescription options

• Oral antibiotics — tetracyclines, especially doxycycline and minocycline, are strongly recommended by the AAD for moderate-to-severe inflammatory acne. They are intended for short-term use (generally up to about 3–4 months) alongside topical retinoids and benzoyl peroxide, then tapered to reduce resistance. Sarecycline is a narrower-spectrum tetracycline developed for acne.
• Hormonal therapy (for women):
• Combined oral contraceptives (e.g., ethinyl estradiol with norgestimate, norethindrone, or drospirenone) reduce androgen-driven sebum; several are FDA-approved for acne. Selection should follow standard contraceptive eligibility (ACOG guidance).
• Spironolactone, an anti-androgen, reduces sebum production and is increasingly used for adult women with hormonal-pattern acne (AAD 2024).
• Isotretinoin — a powerful oral retinoid for severe, nodulocystic, or scarring acne, or acne unresponsive to other treatments; it is the only therapy that addresses all four pathogenic factors and can produce long-term remission. Typical dosing is about 0.5–1 mg/kg/day over several months (NIH/StatPearls).
• Isotretinoin is highly teratogenic (causes severe birth defects). In the U.S., all patients must enroll in the FDA-mandated iPLEDGE Risk Evaluation and Mitigation Strategy, which requires pregnancy prevention (two forms of contraception or confirmed abstinence for those who can become pregnant) and regular pregnancy testing.
• Monitoring may include periodic lipid panels and liver enzymes; common side effects include dryness of the skin, lips, and eyes.

Can acne be prevented or managed long-term?

Acne cannot always be prevented — especially when hormones and genetics are the main drivers — but flares can be reduced and outcomes improved with consistent care:

• Stick to a maintenance routine. Because acne is chronic, ongoing topical retinoid therapy (often with benzoyl peroxide) is the standard way to keep skin clear after initial control, rather than stopping treatment once lesions resolve (AAD 2024).
• Avoid known triggers — comedogenic products, heavy occlusive sunscreens, and unnecessary friction.
• Don't over-treat. Excessive washing, scrubbing, or layering of multiple harsh actives can damage the skin barrier and worsen acne.
• Treat early and treat inflammation promptly to lower the risk of permanent scarring and dark marks.
• Manage underlying conditions such as PCOS where present.
• Be consistent and patient — results build over weeks to months, and stopping too soon is a common reason for relapse.

For established scarring, dermatologic procedures — chemical peels, laser and energy-based devices, microneedling, subcision, and fillers — can improve appearance after active acne is controlled.

When should you see a doctor?

Consider seeing a primary care clinician or dermatologist if:

• OTC treatments haven't helped after 2–3 months of consistent use.
• Acne is moderate to severe, widespread, or involves the chest and back.
• You develop nodules or cysts (deep, painful lumps), which carry a high scarring risk.
• Acne is scarring or leaving persistent dark marks.
• Acne is causing significant emotional distress, anxiety, or low mood.

Seek prompt medical attention for these red flags:

• Sudden, severe, explosive acne with painful nodules, fever, joint pain, or general illness — possible acne fulminans, a rare but serious variant.
• Acne accompanied by signs of hormonal imbalance in women — irregular periods, rapid hair growth or hair loss, or a deepening voice — which may indicate PCOS or another endocrine disorder warranting evaluation.
• Any concern about mood or thoughts of self-harm, which should be raised with a clinician immediately.

What is the outlook (prognosis) for acne?

The outlook for acne is generally very good. The large majority of cases respond well to treatment, and most people see substantial improvement with an appropriate, consistent regimen. Acne commonly improves on its own by the third decade of life as hormones stabilize, though it can persist or recur, particularly in women (NIH/StatPearls).

The main concerns are not danger to physical health but permanent scarring — which affects a meaningful minority and is more likely with severe, inflammatory, or untreated disease — and the psychological burden. Both are strong reasons to treat acne early and adequately rather than waiting for it to "grow out." With modern therapy, including isotretinoin for severe cases, even long-standing, treatment-resistant acne can often be brought into lasting remission.

Frequently asked questions

Does diet cause acne? Diet is not a primary cause, but the evidence increasingly links high–glycemic-index diets (and, in some studies, skim milk) with acne flares in some people. Chocolate and greasy foods have not been proven to cause acne. Dietary changes may help certain individuals but are not a substitute for proven treatments (AAD).

Is it safe to pop pimples? No. Squeezing or picking pushes inflammation deeper, increases the risk of scarring and dark marks, and can spread bacteria. Spot treatments and proper therapy are far safer than manual extraction at home.

How long does acne treatment take to work? Most topical and oral regimens require 6–8 weeks to show clear improvement, and full benefit can take several months. Stopping too early is a leading cause of relapse — and because acne is chronic, ongoing maintenance treatment is usually needed even after the skin clears.

Can adults get acne even if they never had it as teenagers? Yes. Acne can appear for the first time in adulthood (adult-onset acne), and it is more common in women. It is often linked to hormones and may respond well to hormonal therapies such as combined oral contraceptives or spironolactone (NIH/StatPearls).

Why does acne leave dark spots, and do they go away? After inflammation, the skin can produce extra pigment, causing post-inflammatory hyperpigmentation — especially in darker skin tones. These marks usually fade over months and can be improved with sun protection, topical retinoids, azelaic acid, and other treatments, though they take time and differ from true scars, which are textural and may need procedures.

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*This page is for general education and is not a substitute for professional medical advice. Always consult a qualified clinician for diagnosis and treatment decisions tailored to your situation.*