Overview
Acne is a common skin condition that happens when hair follicles become blocked by oil, dead skin cells, and bacteria. It produces spots ranging from small blackheads and whiteheads to deeper, painful cysts. Acne most often affects the face, chest, and back.
How common is it?
Acne is common in teenagers and young adults, but can also affect older adults. It can range from mild spots to painful nodules and scarring.
Causes and risk factors
The sebaceous glands in skin produce an oily substance called sebum. When glands overproduce sebum and dead skin cells block the follicle opening, bacteria called Cutibacterium acnes multiply and trigger inflammation.
Common risk factors
- Hormonal changes during puberty, pregnancy, or menstrual cycle
- Family history of acne
- Certain medications including steroids and lithium
- High-glycaemic diets (some evidence)
- Stress increasing oil production
- Cosmetic products that block pores
Symptoms
- Blackheads (open clogged pores)
- Whiteheads (closed clogged pores)
- Small red tender bumps (papules)
- Pus-filled spots (pustules)
- Firm painful lumps under the skin (nodules)
- Painful pus-filled cysts
- Skin scarring after severe spots
When to see a doctor
See a doctor if over-the-counter products have not helped after 2 to 3 months, if acne is leaving scars, or if it is seriously affecting your confidence or mental health.
Diagnosis
Doctors diagnose acne by examining the skin. They assess the type and severity of spots to guide treatment. Blood tests are occasionally done if a hormonal cause is suspected in women.
Treatments
Topical retinoids and benzoyl peroxide
Topical treatments such as benzoyl peroxide and retinoids are selected according to acne severity. Retinoids help prevent blocked pores, but must not be used during pregnancy or when planning pregnancy. Ask about suitable alternatives.
Antibiotic tablets or gels
Antibiotics may be used with suitable non-antibiotic topical treatment; they should not be used alone. Treatment is usually reviewed after 12 weeks and antibiotics stopped as soon as appropriate to limit resistance. Oral tetracyclines are not suitable during pregnancy or pregnancy planning.
Isotretinoin (Roaccutane)
Isotretinoin is a specialist treatment for severe acne resistant to adequate standard therapy. Monitoring includes mental health and sexual function, as well as other adverse effects. It must not be used in pregnancy; people who could become pregnant need the required pregnancy-prevention safeguards.
Self-care and lifestyle
- Wash affected areas twice daily with a mild soap-free cleanser, not more
- Avoid squeezing spots, which worsens inflammation and increases scarring risk
- Use oil-free, non-comedogenic moisturisers and sun protection
- Change pillowcases frequently and keep hair off your face
Prevention
Acne cannot always be prevented, but consistent gentle skincare, avoiding pore-blocking products, and managing stress can reduce frequency and severity of breakouts.
Sources for targeted updates
Updated: 24 October 2026. Targeted corrections to frequency, treatment, key facts. This update covers the named sections; a full review of the remaining guide is pending.