Almost everyone has acne at some point, and most people in Singapore have tried three or four things before they see a doctor for it. This page is for the point before treatment: what acne actually is, how to tell which type you have, what drives it in a hot, humid climate, and the signs that mean it is time to stop experimenting. Treatment is deliberately not covered here. What I use for each type, and what it costs, is on the acne treatment page, and every treatment is compared in my complete review of acne treatment in Singapore.
What acne is: four things happening inside one pore
Acne is a disease of the pilosebaceous unit, the oil gland and hair follicle that share a single pore. Four things happen in sequence. The sebaceous gland makes more sebum than the pore can clear, under the influence of androgens, the hormones present in both men and women. The lining of the follicle sheds abnormally and the shed cells mix with the sebum to block the pore. Cutibacterium acnes, a bacterium that lives harmlessly on everyone’s skin, multiplies in the trapped sebum. And the immune system reacts to it, which is the inflammation you see as redness and swelling.
Every acne lesion is one of those four steps made visible. A blocked pore with nothing else is a blackhead or whitehead. Add bacteria and inflammation and it becomes a red bump or a pus-filled spot. Let the inflammation rupture the follicle wall and it becomes a nodule or a cyst. That sequence is why acne is graded by what the lesions are, not by how many there are, and why the treatment for a face full of blackheads is different from the treatment for three nodules.
Types of acne, and how to tell them apart
Blackheads and whiteheads (comedonal acne). Blocked pores without inflammation. A blackhead is an open pore whose plug has darkened on contact with air; it is not dirt. A whitehead is the same plug under a closed pore. Both are flat or barely raised, not red, and not sore. They cluster on the forehead, nose and chin, and they are the acne that scrubs and pore strips make worse.
Papules. Small, firm, pink or red bumps, from pinhead to a few millimetres, without a visible head. They are the first inflammatory stage and they are tender rather than painful.
Pustules. Papules with a white or yellow centre of pus. They are the spots people squeeze, and squeezing pushes the contents deeper and is the commonest avoidable cause of a mark that lasts months.
Nodules. Hard, painful lumps set deep in the skin, larger than a pustule and solid to the touch. A nodule can persist for weeks and does not come to a head. Nodules are the lesion most likely to leave a depressed scar.
Cysts. Soft, fluctuant, painful swellings under the skin, formed when inflammation has ruptured the follicle and spread. Cystic acne is the most severe form and the one that should not be managed with skincare alone.
A useful rule: if you can feel it before you can see it, it is a nodule or a cyst, and it belongs in a clinic.
Mild, moderate and severe: what the grades mean
Mild acne is comedones with a few papules. Moderate acne is papules and pustules across a region, with or without a few nodules. Severe acne is many nodules or any cysts, acne on the trunk as well as the face, or acne that is already scarring. The grade decides how urgent treatment is, because scarring risk rises with each step: comedonal acne almost never scars, nodular and cystic acne scars in a large proportion of cases if left for months.
Where acne appears, and what the site tells you
Forehead, nose and chin acne in a teenager is usually comedonal and driven by sebum. Cheek acne is more often inflammatory. Acne along the jawline and lower face in a woman, especially acne that flares with the cycle or persists past 25, has a hormonal pattern that needs its own assessment, covered on the hormonal acne in women page. Acne on the back, chest and shoulders behaves differently from facial acne and is covered on the back, chest and shoulder acne page.
What causes acne, and what does not
Hormones. Androgens drive sebum. Puberty is the obvious trigger, which is why acne begins in the teens, but adult acne in women is common and is usually hormonal in pattern rather than in blood-test result. Polycystic ovary syndrome is one cause worth excluding; see PCOS and acne.
Genetics. If both parents had acne, the chance of moderate to severe acne is high. The inherited part is how the gland responds to normal hormone levels, not the hormone level itself.
Singapore’s climate. Heat and humidity increase sebum flow and sweat, and both add to pore blockage. This does not cause acne in skin that is not prone to it, but it makes prone skin worse and it makes heavy, occlusive skincare a bad idea; the detail is on the acne and oily skin in humid weather page.
Cosmetics and hair products. Occlusive foundations, oils and pomades block pores directly, mostly along the hairline and jaw.
Friction and pressure. Masks, helmet straps, phones held against the cheek and habitual touching produce acne in the contact area.
Diet. The evidence supports two associations, high-glycaemic-load diets and, less consistently, skimmed milk. It does not support chocolate, oily food or any single food as a cause. The diet and acne page sets out the studies.
Stress and sleep. Both worsen existing acne through hormonal pathways; neither starts it.
What does not cause acne. Dirt, poor hygiene, and not washing enough. Over-washing and scrubbing make acne worse by irritating the follicle. Acne is not contagious.
Acne marks and acne scars: what is left behind
When a lesion heals it can leave a flat red mark, a flat brown mark, or a change in the skin’s surface. The red and brown marks fade, slowly, and are not scars. A pit, a rolling depression or a raised lump is a scar and does not fade on its own. The difference matters because the treatments are entirely separate: marks are treated with lasers that target colour, scars with treatments that rebuild the skin. Which one you have is sorted out on the acne marks vs acne scars page, and the scar types are described on the types of acne scars page.
When acne needs a doctor
Skincare and over-the-counter products are a reasonable first step for comedonal acne and a few papules, given twelve weeks of consistent use. See a doctor sooner if any of the following applies: you can feel nodules or cysts; acne is leaving marks or pits; it is on the back or chest as well as the face; it has not improved after twelve weeks of a proper routine; it flares with your cycle or sits along the jaw; or it is affecting how you feel about going out. Each of those is a reason acne will not resolve with skincare alone, and each has a specific treatment on the acne treatment page.
Common questions about acne
Is acne caused by dirty skin?
No. Acne starts inside the pore with sebum and shed cells; dirt on the surface is not the cause, and washing more than twice a day makes acne worse by irritating the follicle.
Does acne go away on its own?
Teenage acne often settles in the early twenties as sebum production falls. Adult acne, particularly hormonal acne in women, tends to persist and recur until the driver is treated. Nodular and cystic acne should not be left to run its course because of scarring.
What is the difference between a pimple and acne?
A pimple is one lesion. Acne is the condition that produces them. Treating pimples one at a time, with spot creams or by squeezing, does nothing about the process that made them.
Why do I still have acne in my thirties?
Adult acne is common, more so in women, and is usually hormonal in pattern: jawline and lower face, flaring with the cycle. It responds to treatment aimed at the driver rather than to stronger skincare.
Can acne be cured?
Acne can be controlled, and in most people it can be controlled well enough that it stops being part of daily life. Whether it comes back depends on the treatment chosen and on the maintenance plan, which is the subject of the review of acne treatment in Singapore.
Book a consultation with Dr Gerard Ee at The Clifford Clinic
Dr Gerard Ee consults and performs acne treatment at The Clifford Clinic, 50 Raffles Place, Singapore. Consultations are by appointment. Message the clinic on WhatsApp, or call 6532 2048.
Selected References
Published studies cited on this page
- Moradi Tuchayi S, Makrantonaki E, Ganceviciene R, Dessinioti C, Feldman SR, Zouboulis CC. Acne vulgaris. Nat Rev Dis Primers. 2015;1:15029. doi:10.1038/nrdp.2015.29
- Zouboulis CC, Coenye T, He L, et al. Sebaceous gland biology and acne. Exp Dermatol. 2020. doi:10.1111/exd.14172
- Reynolds RV, Yeung H, Cheng CE, et al. Guidelines of care for the management of acne vulgaris. J Am Acad Dermatol. 2024;90(5):1006.e1–1006.e30. doi:10.1016/j.jaad.2023.12.017
- Eichenfield DZ, Sprague J, Eichenfield LF. Management of acne vulgaris: a review. JAMA. 2021;326(20):2055–2067.
- Elhassan YS, Idkowiak J, Smith K, et al. Approach to the patient with hyperandrogenism. Clin Endocrinol (Oxf). 2025. doi:10.1111/cen.15265
This page is written by Dr Gerard Ee from his own clinical practice and the published studies cited above. It is general information and not a substitute for a consultation.
