Acne UK: Types, Causes & Symptoms Explained
Acne explained — what it is, types of spots, causes and triggers. A clinical UK guide to acne vulgaris from Access Doctor.
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Acne UK: Types, Causes & Symptoms Explained
What acne is, the different types of spots, how it is graded, what causes and triggers it, how to tell it from rosacea, and how it is treated in the UK.
Part of our acne health guides. Looking for treatment? See our acne treatments.
Key fact: Acne is very common: about 95% of people aged 11 to 30 are affected to some extent, according to the NHS. It is a condition of the hair follicle and oil gland, not a result of poor hygiene, and it is very treatable. Treating it early is the best way to prevent scarring.
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See acne treatments →What is acne?
Acne (acne vulgaris) is a long-term condition of the pilosebaceous unit: the hair follicle and the oil (sebaceous) gland attached to it. The follicle becomes blocked with oil and dead skin cells, and the skin bacterium Cutibacterium acnes (formerly Propionibacterium acnes) multiplies inside it and triggers inflammation. The result is the range of spots associated with acne: blackheads, whiteheads, red spots, pus-filled spots and, in more severe acne, nodules and cysts.
It most often affects the face, but also the back, chest and shoulders, where there are the most oil glands. Acne on the body behaves differently and is slower to clear, which our guide to back, chest and body acne covers in detail. Acne is most common in the teenage years, but it can start or continue in adulthood, especially in women; see adult and hormonal acne.
How acne forms
Four processes work together to cause acne. Most effective treatments target more than one of them.
| Process | What happens |
|---|---|
| Excess oil | Androgens (hormones present in both sexes) enlarge the oil glands and increase oil production beyond what the pore can clear |
| Blocked pores | Skin cells lining the follicle shed too slowly and stick together, forming a plug |
| Bacteria | C. acnes multiplies in the oil-rich, blocked follicle |
| Inflammation | The immune response to those bacteria causes redness, swelling and pain |
A blocked follicle (a comedone) is the starting point. When the blockage is open to the air, the trapped material darkens, forming a blackhead. When it's closed over by skin, it forms a whitehead. If bacteria multiply and inflammation develops, it becomes a red papule or a pus-filled pustule. Deeper inflammation causes nodules and cysts.
Types of acne spots
| Type | What it looks like | Inflamed? |
|---|---|---|
| Blackheads (open comedones) | Blocked pores open to the surface; dark because the contents oxidise, not because of dirt | No |
| Whiteheads (closed comedones) | Blocked pores closed over by skin; small, skin-coloured bumps | No |
| Papules | Small, red, raised, tender bumps | Yes |
| Pustules | Red spots with a white or yellow head of pus | Yes |
| Nodules | Large, hard, painful lumps deep under the skin | Yes (severe) |
| Cysts | Large, pus-filled lumps deep in the skin; the highest risk of scarring | Yes (severe) |
Most people have a mix. Whether acne is mainly blackheads and whiteheads or mainly inflamed spots affects which treatment suits it best.
Not everything that looks like acne is acne. Itchy bumps that are all the same size, spots clustered around the mouth, or painful lumps in the armpits and groin all point elsewhere; see what else looks like acne.
Grades of acne: mild, moderate and severe
- Mild acne: mostly blackheads and whiteheads, with a few red or pus-filled spots. Usually treated with creams or gels.
- Moderate acne: more widespread red and pus-filled spots, sometimes with a few nodules. Often needs a cream or gel together with an antibiotic tablet.
- Severe acne: widespread inflamed spots, nodules and cysts, often with scarring. Needs prompt treatment, and often a dermatologist.
Doctors sometimes use a scale such as the Leeds grading scale, which grades acne from 0 (no acne) to 4 (severe, widespread nodules and cysts) using photographs as a guide. NICE guidance on acne (NG198) groups it more simply into mild to moderate and moderate to severe, and bases treatment on that.
Why grade matters: severe acne with nodules and cysts carries the highest risk of permanent scarring. It should be treated early rather than waited out. If you have deep, painful lumps or cysts, get them assessed rather than relying on over-the-counter products.
Severe acne that hasn't responded to other treatment, or that is scarring, may need isotretinoin. In the UK, isotretinoin can only be prescribed by, or under the supervision of, a consultant dermatologist, so it isn't available online; your GP can refer you.
Acne or rosacea?
Acne and rosacea can look alike, because both cause red bumps and pus-filled spots on the face. They are different conditions with different treatments, and some acne treatments can irritate rosacea-prone skin.
| Acne | Rosacea | |
|---|---|---|
| Blackheads and whiteheads | Yes, usually | No |
| Where | Face, chest, back and shoulders | Central face: cheeks, nose, forehead and chin |
| Flushing and persistent redness | Not typical | Common, with visible small blood vessels |
| Usual age it starts | Teens, but any age | Usually 30 or over |
| Typical triggers | Hormonal changes, some medicines, heavy skincare | Sun, alcohol, heat, spicy food, stress |
For more on rosacea, see our rosacea guide and rosacea treatments.
What causes acne?
Acne is driven mainly by hormones and genes, not by lifestyle alone.
Hormones
Androgens enlarge the oil glands and increase oil production, which is why acne peaks in puberty and can flare around periods.
Genes
Acne runs in families. If both parents had acne, you're more likely to get it, which is a reason to treat it early.
Bacteria
Overgrowth of C. acnes inside blocked follicles turns a blackhead or whitehead into an inflamed spot.
Immune response
How strongly the skin reacts to those bacteria varies from person to person, and largely decides how inflamed acne becomes.
In women, acne often follows the menstrual cycle, and it can be a feature of polycystic ovary syndrome (PCOS), especially with irregular periods and excess hair growth. Acne that starts or continues in adulthood tends to be deeper, lower on the face and cyclical, and is covered in adult and hormonal acne.
Common acne triggers
Triggers don't cause acne on their own, but they can make it worse:
- Hormonal changes: puberty, periods, pregnancy, PCOS, and stopping the combined pill
- Some medicines: steroids, lithium, some anti-epilepsy medicines, and some progestogen-only contraceptives
- Heavy, oily skincare and make-up that block pores
- Friction and pressure: helmet straps, face masks, rucksacks and tight clothing
- Picking and squeezing: makes inflammation worse and greatly increases the risk of scarring
- Diet: the evidence is limited; high-glycaemic diets and, in some studies, skimmed milk may play a small part for some people
On hygiene: acne isn't caused by dirt. Washing more than twice a day, or scrubbing hard, irritates the skin and can make acne worse. A gentle cleanser twice a day is enough.
Acne myths
- Myth: acne is caused by poor hygiene. It's driven by hormones, genes and what happens inside the follicle, not dirt. Over-washing makes it worse.
- Myth: chocolate and greasy food cause acne. The link with diet is weak and inconsistent; no single food causes acne for most people.
- Myth: sunbathing clears acne. Sun may hide redness for a while, but it damages the skin and can make dark marks worse.
- Myth: you should let acne run its course. Untreated inflamed acne can leave permanent scars; early treatment protects the skin.
- Myth: popping spots helps them heal. Squeezing pushes inflammation deeper, slows healing and increases scarring.
- Myth: once it clears, you can stop everything. Acne usually returns if treatment stops completely; see acne maintenance and relapse.
Acne scarring and why early treatment matters
One of the most important reasons to treat acne, rather than wait for it to clear, is to prevent scarring. Inflamed acne, especially nodules and cysts, can damage the deeper layers of skin and leave permanent scars (such as ice-pick or rolling scars) or dark marks that last for months.
Scarring is far easier to prevent than to treat, which is why NICE recommends treating acne promptly and avoiding picking or squeezing. Most of what people call scarring is actually flat pigmentation, which fades on its own; our guide to acne scars and marks explains how to tell the difference.
How acne is treated
NICE guidance (NG198) recommends a 12-week course of treatment, then a review. Treatment depends on how severe the acne is:
| Acne | First treatment (NICE) | Examples |
|---|---|---|
| Mild to moderate | A gel that combines two treatments, used for 12 weeks | Epiduo (adapalene with benzoyl peroxide), Treclin (tretinoin with clindamycin), Duac (benzoyl peroxide with clindamycin) |
| Moderate to severe | Epiduo or Treclin for 12 weeks, or an antibiotic tablet with a gel that doesn't contain an antibiotic (Epiduo, or azelaic acid) for up to 6 months | Lymecycline or doxycycline with Epiduo |
| Women with acne | A combined contraceptive pill can be added to a cream or gel. Co-cyprindiol is only used for moderate to severe acne that hasn't improved with other treatments | Dianette (co-cyprindiol) |
| Severe, scarring, or not improving | Referral to a dermatologist | Isotretinoin (specialist only) |
| Once clear | Keep using a cream or gel without an antibiotic to stop it coming back | Differin (adapalene), Acnecide (benzoyl peroxide) |
Antibiotics, whether tablets or creams, are never used on their own, because acne bacteria can become resistant to them. Most treatments take several weeks to work, and skin may get a little worse or drier first. Many acne treatments, including retinoids and tetracycline antibiotics, can't be used in pregnancy. For the full range we supply to adults, see our acne treatments.
When to seek medical help
Most acne can be treated effectively. Get advice if:
- over-the-counter products haven't helped after 2 to 3 months
- you have moderate to severe acne with many red spots, nodules or cysts
- your acne is leaving scars or long-lasting dark marks
- acne is affecting your confidence, mood or everyday life
- you have acne with irregular periods or excess hair growth (possible PCOS)
- your spots itch, are all the same size, or got worse on antibiotics, which suggests it may not be acne
Get urgent same-day medical help if you suddenly develop severe, painful acne with a high temperature, joint pain or feeling generally unwell. This can be a rare, serious form of acne (acne fulminans) that needs urgent specialist treatment. If acne is making you feel very low or hopeless, speak to your GP, call NHS 111, or contact Samaritans on 116 123.
For children and teenagers, the case for treating early is the same; our guide to acne in teenagers is written for parents. We supply acne treatment online to adults aged 18 and over; under-18s should see their GP or a pharmacist.
All acne guides
Our acne guides go into more depth on each topic.
Acne creams and gels compared
Epiduo, Treclin, Duac, Differin, Acnecide and azelaic acid side by side.
Acne antibiotics compared
Lymecycline, doxycycline, oxytetracycline and minocycline.
Dianette (co-cyprindiol) for acne
Who it's for, safety and how long it takes.
Tretinoin for acne in the UK
Licensed options and tretinoin vs adapalene.
Acne skincare routine
Morning and night, with your treatment.
Acne treatment side effects
What's normal, and when to stop.
Adult and hormonal acne
The jawline pattern, period flares, PCOS and the pill.
Acne scars and marks
What fades on its own, and what doesn't.
Back, chest and body acne
Why it's slower to clear, and what it's confused with.
What else looks like acne
Fungal acne, perioral dermatitis and other lookalikes.
Acne maintenance and relapse
Why acne comes back when you stop treatment.
Acne in teenagers
For parents: what helps and what doesn't.
Isotretinoin (Roaccutane) explained
Who it's for, and how UK referral works.
Skinoren for acne: week by week
The purging phase and a realistic timeline.
Skinoren UK: the complete guide
How to use it, dosing and results.
Azelaic acid (Skinoren) guide
How it works and who it suits.
Frequently asked questions
Is acne caused by poor hygiene?
No. Acne is caused by excess oil production driven by hormones, blocked follicles, bacterial overgrowth, and inflammation, not by dirt. Washing too often or scrubbing can irritate the skin and make acne worse. A gentle cleanser twice a day is sufficient.
What causes acne?
Acne is caused by four processes working together: excess oil production, blocked pores from dead skin cells, overgrowth of the skin bacterium Cutibacterium acnes, and inflammation. Hormones and genes are the main drivers, and some medicines, heavy skincare and picking can make it worse.
What is acne vulgaris?
Acne vulgaris is the medical name for common acne: a long-term condition of the hair follicles and oil glands. It causes blackheads and whiteheads, red and pus-filled spots and, in severe acne, nodules and cysts. The NHS says about 95% of people aged 11 to 30 are affected to some extent.
Why do adults get acne?
Acne often clears by the mid-20s, but it can carry on into adult life or start for the first time, especially in women. Adult acne is often linked to hormonal changes, such as the menstrual cycle, stopping the pill, pregnancy or PCOS, as well as some medicines and genes. It tends to affect the lower face, jawline and neck.
What is the difference between a blackhead and a whitehead?
Both are blocked follicles (comedones). A blackhead is open to the surface, so the trapped material oxidises and darkens: the dark colour is oxidation, not dirt. A whitehead is closed over by skin, appearing as a small skin-coloured bump. Neither is inflamed.
What are the grades of acne on the Leeds scale?
The Leeds grading scale grades acne from 0 (no acne) to 4 (severe, widespread nodules and cysts). In the UK, NICE groups acne more simply as mild to moderate, or moderate to severe, and bases treatment on that. Severe acne with nodules, cysts or scarring usually needs a dermatologist.
What is the difference between acne and rosacea?
Acne causes blackheads and whiteheads as well as red spots, and can affect the face, chest and back. Rosacea doesn't cause blackheads or whiteheads; it causes flushing, persistent redness and visible blood vessels across the central face, often triggered by sun, alcohol, heat or spicy food, and usually starts after 30.
Does diet cause acne?
The evidence linking diet to acne is limited and inconsistent. Some studies suggest high-glycaemic-index diets and in some cases skimmed milk may modestly worsen acne in certain people, but no single food causes acne for most. Hormones and genetics are far more important.
Will acne go away on its own?
Acne often improves with age as hormones settle, and often clears by the mid-20s, but this can take years, and inflamed acne can leave permanent scarring in the meantime. Because scarring is much easier to prevent than treat, it is usually better to treat moderate to severe acne early.
Can squeezing spots make acne worse?
Yes. Squeezing or picking pushes inflammation deeper, delays healing, spreads bacteria, and greatly increases the risk of permanent scarring and dark marks. It is one of the most common avoidable causes of acne scarring.
Is acne linked to PCOS?
It can be. Acne is one feature of polycystic ovary syndrome (PCOS), particularly alongside irregular periods, excess hair growth, and difficulty losing weight. Persistent adult acne in women that does not respond to standard treatment may need assessment for PCOS.
Why does my acne come back whenever I stop treatment?
Because acne treatment controls the process causing acne rather than curing it. The hormonal drivers behind excess oil and blocked follicles don't change because the skin has cleared, so stopping lets the process start again. Skin often stays clear for a few weeks after stopping, which is long enough to think the acne has gone. A lighter, ongoing maintenance treatment is what keeps most people clear.
When should I see a doctor about my acne?
Get advice if over-the-counter products haven't helped after 2 to 3 months, if you have nodules or cysts, if acne is leaving scars or affecting your mood, or if you have irregular periods or excess hair growth too. Get urgent same-day help if you suddenly develop severe, painful acne with a fever or joint pain.
Ready to treat your acne?
Complete a short online consultation about your skin and any treatments you have tried. A GPhC-registered pharmacist prescriber checks your answers and, if treatment is suitable, we dispatch it from our UK pharmacy. For adults 18 and over.
Start Acne Consultation →References
- National Institute for Health and Care Excellence. Acne vulgaris: management (NG198). nice.org.uk/guidance/ng198
- NICE Clinical Knowledge Summaries. Acne vulgaris. cks.nice.org.uk/topics/acne-vulgaris
- NHS. Acne. nhs.uk/conditions/acne
- British Association of Dermatologists. Acne: patient information leaflet. bad.org.uk
- MHRA. Isotretinoin: new safety measures, including prescribing by or under the supervision of a consultant dermatologist (2023). gov.uk/drug-safety-update
- DermNet. Acne. dermnetnz.org/topics/acne
Medical disclaimer: This page is for information only and isn't a substitute for medical advice. Many acne treatments, including retinoids and tetracycline antibiotics, must not be used in pregnancy. Prescription treatments need a clinical consultation before they can be supplied. Always follow your prescriber's advice and the leaflet. In a medical emergency, call 999.
