Published 31 October 2026 · Reviewed by Dr Sin Yong
Acne on the face is graded by the type of spot that dominates and how much skin it covers. Mild acne is mostly blackheads and whiteheads with a few small red spots; moderate acne has many inflamed papules and pustules; severe acne has deep nodules or cysts, or is scarring. The grade, not a product label, decides the treatment.
Short answerDoctors classify acne by lesion type (comedonal, inflammatory or nodulocystic), by extent and by whether it is scarring. Mild acne usually starts with topical treatment, moderate acne often adds a time-limited oral course, and severe or scarring acne is treated early with prescription medicine, because grade predicts scarring risk more than any other feature.
A pimple is a single spot; acne is the condition that keeps producing them. Almost everyone has an occasional pimple, often around a period, after a stressful week or under a mask or helmet strap, and it settles on its own within days. Acne is diagnosed when spots keep recurring over weeks and months, usually in a pattern across the face, chest or back, with comedones, the blackheads and whiteheads, sitting alongside inflamed spots.
The distinction matters because the two are handled differently. A pimple needs little more than being left alone, a gentle routine and perhaps an over-the-counter benzoyl peroxide or salicylic acid product. Acne involves the four drivers in the follicle at once, and treating it means acting on more than the spot in front of you. Some spots are neither: uniform, itchy bumps on the chest and back suggest fungal folliculitis, and small papules clustered around the mouth or nose may be perioral dermatitis or a Demodex-related problem, none of which respond to acne treatment. Squeezing a pimple pushes inflammation deeper and raises the risk of a dark mark or scar, which in Fitzpatrick III to V skin can outlast the spot by months.
Acne face types: comedonal, inflammatory and nodulocystic
Acne on the face is described by its lesions: comedones, which are blocked follicles without inflammation; papules and pustules, which are inflamed; and nodules and cysts, which are deep. A 2021 review of acne management in JAMA classified acne by patient age, lesion type, distribution across face and trunk, and severity, including whether scarring is present, and estimated that acne affects about 85% of people aged 12 to 24.
Illustrative image — not a patient.
Lesion
What it is
What it looks like
Scarring risk
Whitehead (closed comedone)
Follicle plugged beneath a closed surface
Small skin-coloured bump
Low unless it inflames
Blackhead (open comedone)
Plugged follicle with an open, dilated pore
Dark dot in a pore
Low
Papule
Inflamed follicle
Small red, tender bump with no head
Moderate; marks are common
Pustule
Inflamed follicle with pus at the surface
Red spot with a yellow-white head
Moderate, higher if squeezed
Nodule
Deep inflammation in the dermis
Firm, painful lump lasting weeks
High
Cyst
Deep, soft, fluid-filled inflamed lesion
Tender swelling that may drain
High
Most faces show a mix. The grade reflects what dominates and how much of the face is involved. The comedone types are compared on whiteheads vs blackheads.
Mild acne, moderate acne and severe acne compared
Mild, moderate and severe acne differ in how many spots there are, how deep they go and whether they are leaving scars. There is no single universal scale; doctors use several, but all of them separate these three broad groups, and each group has a different starting point.
Grade
Typical picture
Usual first step
Page
Mild acne
Mostly blackheads and whiteheads, a few small red spots
Topical retinoid, benzoyl peroxide or both; gentle skincare
Mild acne is comedone-led. It responds to a topical retinoid, which stops new plugs forming, often with benzoyl peroxide for the few red spots. It does not need antibiotics, and scrubbing or drying it out makes it worse. Many teenagers stay at this grade; see teen acne treatment.
Moderate acne
Moderate acne is inflammation-led: red papules and pustules across the cheeks, forehead, chin or jaw, often leaving dark marks in Asian skin. Over-the-counter products are usually not enough. A topical combination plus a time-limited oral antibiotic course is common, and in adult women a hormonal option may replace the antibiotic.
Severe acne
Severe acne includes nodules and cysts, acne that is scarring, or acne that has not responded to earlier steps. Waiting for it to settle is the decision most likely to leave scars, so treatment starts early; see isotretinoin for acne.
“The name on a cleanser does not grade your acne. What sits in the skin, and how deep it goes, decides the plan.”
Dr Sin YongOn grading acne
Grading Decides the Approach
Acne is classified by what predominates. The grade is not a severity score for its own sake — it tells you which of the four factors is driving the presentation, and therefore what the plan has to address.
Acne grading
Grade
What it describes
Comedonal
Open and closed comedones — blackheads and whiteheads — without significant inflammation. The problem here is follicular obstruction rather than inflammatory activity.
Papulopustular
Inflammatory papules and pustules alongside comedones. Inflammation has become the dominant feature, and post-inflammatory pigment change becomes a consideration.
Nodulocystic
Deep, tender nodules and cysts extending into the dermis. This is the presentation most associated with scarring, and the one where early medical management matters most.
Cystic acne treatment is where early intervention matters most, because nodulocystic disease is the grade most strongly associated with lasting scarring. Waiting to see whether it settles is the decision that most often produces scarring that later needs revision.
Is there such a thing as bacterial acne?
Bacterial acne is a popular term rather than a diagnosis: all acne involves skin bacteria, but acne is not a simple infection. Cutibacterium acnes, the bacterium most linked to acne, lives in everyone's follicles. A 2018 review in the Journal of the European Academy of Dermatology and Venereology concluded that people with acne do not carry more C. acnes in their follicles than people without it; instead, a loss of balance between bacterial strains and activation of the skin's innate immune response drive the inflammation.
That explains how acne is treated. Antimicrobials such as benzoyl peroxide reduce bacteria and inflammation, but they work better combined with a retinoid that acts on the blocked follicle. Oral antibiotics are used in time-limited courses and paired with topical treatment to limit resistance.
When it really is an infection
Some conditions that look like acne are infections, or are driven by organisms other than C. acnes:
Fungal acne (Malassezia folliculitis): itchy, uniform bumps caused by a yeast, which antibiotics can worsen; see fungal acne.
Bacterial folliculitis: pustules centred on hairs, often after shaving or in hot tubs.
Gram-negative folliculitis: a flare of pustules around the nose and mouth in someone on long-term antibiotics.
These need a different plan, which is why acne that does not respond as expected is re-examined rather than simply given a stronger antibiotic.
Acne mechanica and maskne: acne from friction
Acne mechanica is acne triggered or worsened by repeated friction, pressure, heat and occlusion on the skin, and maskne is the name given to the form caused by face masks. A 2022 review in the Journal of Clinical Medicine described maskne as a form of mechanical acne caused by continuous fabric contact and friction, with the warmer environment under a mask altering skin bacteria and sebum production.
It appears where something rubs: under helmet chin straps and sports headbands, along bra and backpack straps, under tight synthetic sportswear and on the chin of people who rest it on a hand or phone. In Singapore's heat and humidity, sweat trapped against the skin adds to the effect.
Reduce the friction: looser, breathable fabrics, padding under straps, a clean mask changed once damp.
Shower and change soon after exercise.
Use light, non-comedogenic products under anything that covers the skin.
Treat the acne itself as you would elsewhere; removing friction helps but rarely clears established acne alone.
Does sugar cause acne? What the diet evidence shows
Sugar does not cause acne on its own, but a high glycaemic diet, rich in sugar and refined carbohydrate, is associated with more acne and with worse acne in some people. A 2022 systematic review in JAAD International of 34 studies found that a high glycaemic index and glycaemic load were positively associated with acne and acne severity, supported by randomised trials, while the evidence on dairy was mixed and seemed to depend on sex, ethnicity and dietary habits.
The proposed link runs through insulin and insulin-like growth factor 1, which raise androgen activity and sebum output. The effect in trials is modest, and diet is one factor among several.
Cutting down on sugary drinks, sweets and refined carbohydrate is reasonable and good for health generally.
Crash diets or removing whole food groups are not needed and are not supported by the evidence.
Diet supports treatment; it does not replace it, particularly for moderate or severe acne.
Acne skin care: what helps at every grade
Acne skin needs gentle, consistent care that does not add oil, friction or irritation; skincare supports treatment at every grade but does not replace it from moderate acne upwards.
Cleanse gently twice a day; over-washing and scrubs irritate the follicle.
Moisturise with a light, non-comedogenic product, especially when using a retinoid or benzoyl peroxide.
Do not squeeze; it pushes inflammation deeper and raises the risk of marks and scars.
Be patient with actives: retinoids work gradually and can cause an early flare known as purging.
When to see a doctor
See a doctor when acne is painful, leaving marks or scars, or not improving after a few months of consistent care, or when it starts suddenly in adulthood with irregular periods or excess hair. At the clinic on Orchard Road, Singapore, Dr Sin Yong grades the acne, rules out lookalikes and plans treatment for the grade in front of him; lasers such as R2 Glow are added for inflammation alongside medication, not instead of it. The full treatment ladder is on acne treatment in Singapore.
Your next step
1. MessageWhatsApp +65 8023 7170 with what is bothering you. A reply comes from the clinic, not a bot.
2. AssessmentDr Sin Yong examines you himself on Orchard Road, with ultrasound where earlier filler is involved.
3. A plan in writingWhat he would do, what he would not, the fee factors, and the option of no treatment.
Every treatment is performed by Dr Sin Yong personally. Singapore Medical Council registered · invited to share his clinical expertise internationally for CLASSYS, DEKA, Fotona, Hironic and Ilooda.
Bring photos of your acne at its worst and a list of what you have already tried, with how long you used each. How consultations work.
What to do with a single blind pimple is set out separately.
Frequently Asked Questions
It is better not to. Squeezing forces inflammation deeper into the skin, which raises the risk of a dark mark, infection and scarring, particularly with deep or painful spots. A whitehead that has come to the surface will usually drain on its own, and a hydrocolloid patch can protect it from picking. A large, painful lump that never comes to a head is a nodule or cyst, and that is one to have assessed rather than squeezed.
Not reliably. Most inflamed spots take several days to settle as the inflammation resolves. Over-the-counter benzoyl peroxide or a hydrocolloid patch can help a surface spot settle and keep fingers away from it. For a single large, painful cyst before an important event, a doctor may consider a dilute corticosteroid injection into that lesion, which acts on that one spot only and does not treat acne as a condition.
Acne is mild when it is mostly blackheads and whiteheads with a few small red spots, moderate when there are many inflamed red spots or pustules across the face, and severe when there are deep, painful nodules or cysts, or the acne is leaving scars. Any scarring moves acne into a higher grade for treatment, because preventing further scars becomes the priority.
Mild acne often improves over time, particularly in the late teens, but it can persist into adulthood and comedones can become inflamed spots. A topical retinoid and gentle skincare usually control mild acne, and treating it early lowers the chance of dark marks. If mild acne is spreading, inflaming or leaving marks after a few months of consistent care, see a doctor.
Moderate acne is often treated with a time-limited course of an oral antibiotic such as doxycycline, combined with a topical retinoid or benzoyl peroxide to improve the effect and limit resistance. Antibiotics are not used alone or long term. In adult women, a hormonal option may be used instead, and isotretinoin is considered when moderate acne does not respond or is scarring.
Bacterial acne is a popular term for inflamed acne, but acne is not a simple infection: the bacterium involved lives in everyone's skin, and inflammation is driven by imbalance and the immune response. It is treated with benzoyl peroxide, a topical retinoid and, where needed, a short oral antibiotic course. Bumps that do not respond may be fungal or bacterial folliculitis instead.
Acne mechanica looks like ordinary acne, with comedones, red papules and pustules, but it sits exactly where something rubs or presses on the skin, such as under a mask, helmet strap, sports bra, backpack or tight clothing. It often flares with heat and sweat. Reducing the friction helps, and the acne is treated with the same topical options used elsewhere.
Cutting out sugar alone rarely clears acne. Studies link a high glycaemic diet with more acne and worse severity, so reducing sugary drinks and refined carbohydrate may help some people, but the effect is modest. Acne is driven by hormones, follicle blockage, bacteria and inflammation, and moderate or severe acne still needs medical treatment alongside any change in diet.
Maskne is acne caused or worsened by wearing a face mask, a form of acne mechanica from friction, trapped heat and sweat. It still happens to people who wear masks for work, such as healthcare and food-service staff. Changing a damp mask, choosing smooth breathable fabric, avoiding heavy make-up underneath and treating the acne itself all help.
Acne location can hint at triggers but does not map to internal organs. Acne on the chin and jaw in adult women often has a hormonal component; acne at the hairline can relate to hair products; acne under masks or straps suggests friction. Face-mapping charts linking spots to the liver or bowel are not supported by evidence. Grade matters more than location for treatment.
References
Management of Acne Vulgaris: A Review. JAMA 326(20):2055-2067, 2021. source
Cutibacterium acnes (Propionibacterium acnes) and acne vulgaris: a brief look at the latest updates. Journal of the European Academy of Dermatology and Venereology 32 Suppl 2:5-14, 2018. source
Maskne: The Epidemic within the Pandemic: From Diagnosis to Therapy. Journal of Clinical Medicine 11(3), 2022. source
Diet and acne: A systematic review. JAAD International 7:95-112, 2022. source
About this page: written and medically reviewed by Dr Sin Yong, MBBS (NUS), MRCS (Edinburgh) · Last reviewed 31 October 2026 · Illustrative images only, not patients · Editorial policy
