Types of Acne: Blackheads to Cysts, and How Severe Yours Is

Acne is not one single thing. Dermatologists sort it two ways: by the type of spot (non-inflamed blackheads and whiteheads, or inflamed papules, pustules, nodules and cysts) and by overall severity (roughly mild, moderate or severe). Knowing which you are dealing with is the quickest way to tell whether drugstore products are a reasonable first step or whether you need a dermatologist sooner rather than later.

How common is acne?

Very. A global review of acne epidemiology estimated that acne affects 9.4% of the world’s population at any one time, making it the eighth most prevalent disease worldwide. In the US, the American Academy of Dermatology (AAD) calls acne the most common skin condition in the country, affecting up to 50 million Americans a year, and notes that roughly 85% of people aged 12 to 24 have at least minor acne.

Teens get most of the attention, but acne is not only a teenage problem. The NIH’s StatPearls review of acne vulgaris puts adolescent prevalence estimates anywhere from 35% to over 90% depending on the study, and notes that acne after adolescence mostly affects women. If that’s you, I’ve gone deeper on the adult pattern in hormonal acne in adults.

What actually causes an acne spot?

Every acne lesion starts in a pilosebaceous unit, the hair follicle plus its oil gland. According to StatPearls, four processes drive acne: extra sebum (oil) production, follicles that shed skin cells abnormally and plug up (hyperkeratinization), overgrowth of the skin bacterium Cutibacterium acnes, and inflammation. Androgen hormones stimulate the oil glands, which is why acne often starts around puberty.

The very first lesion is a microcomedo, a plug too small to see. From there it can become a visible comedo (blackhead or whitehead) or, if inflammation kicks in, an inflamed spot. That progression is the reason most effective treatment plans aim to prevent new plugs rather than just attack the spots you can see.

What are the different types of acne?

Non-inflammatory acne: whiteheads and blackheads

Comedones are clogged pores without much redness. MedlinePlus explains it simply: if the top of the plug is white, it’s a whitehead; if it’s dark, it’s a blackhead. Whiteheads are closed comedones (the pore opening is blocked beneath the skin surface), while blackheads are open. The dark colour is surface pigment (melanin), not dirt, so scrubbing harder won’t wash it away. There’s a full breakdown in blackheads vs whiteheads.

Papules

The AAD describes papules as small, red bumps that feel hard. They happen when the wall of a clogged follicle becomes inflamed, and there’s no visible pus head.

Pustules

Pustules are what most people picture as “pimples”: inflamed bumps with a yellow or white centre filled with fluid. The AAD’s advice is to resist the temptation to pop them, because squeezing can push debris deeper and raise the risk of scarring (more on that in should you pop pimples?).

Nodules and cysts

These are the deep, often painful lumps. The AAD explains that when inflammation goes deep into the skin, an acne nodule or cyst develops, and its patient guide warns that these lesions penetrate deep into the skin and often cause permanent acne scars. The AAD is blunt that you’ll need a dermatologist’s help for this type. StatPearls groups these deepest lesions under “nodulocystic acne.” I’ve covered this in detail in cystic acne.

How is acne severity graded: mild, moderate or severe?

Here’s something that surprised me: there is no single official scale. In its guidance for drug trials, the US Food and Drug Administration states that “there is no single, standardized grading system for severity of acne.” Dermatologists and researchers use several different scales, though the 2024 AAD acne guideline advises clinicians to use some consistent grading approach to guide treatment decisions.

The UK’s NICE guideline gives one of the clearest, count-based definitions (quoted here from NHS Scotland’s acne pathway, which adapts NICE 2021):

• Mild to moderate: any number of comedones, and/or up to 34 inflammatory lesions, and/or up to 2 nodules.
• Moderate to severe: 35 or more inflammatory lesions and/or 3 or more nodules.

StatPearls describes the extremes in plainer terms: mild acne means scattered comedones or small inflamed papules without scarring, while moderate-to-severe acne involves prominent comedones, large inflamed papules and pustules, and nodules with scarring, often across several body areas.

Which treatments work for which type of acne?

The 2024 AAD guideline, based on a systematic review using the GRADE method, makes strong recommendations for benzoyl peroxide, topical retinoids, topical antibiotics and oral doxycycline, and conditional (weaker-evidence or more case-by-case) recommendations for salicylic acid, azelaic acid, topical clascoterone, oral minocycline and sarecycline, combined oral contraceptive pills and spironolactone. Oral isotretinoin is strongly recommended for acne that is severe, scarring, causing psychosocial burden or not responding to standard treatment.

Matched to lesion type, the AAD’s patient advice goes roughly like this:

• Blackheads and whiteheads: a retinoid plus a benzoyl peroxide wash. Adapalene 0.1% gel became the first retinoid approved over the counter for acne in the US, for ages 12 and up (sold as Differin).
• Papules and pustules: a wash containing benzoyl peroxide or salicylic acid. OTC rules in the US allow benzoyl peroxide at 2.5% to 10% and salicylic acid at 0.5% to 2%.
• Nodules and cysts: a dermatologist. OTC products aren’t enough here.

Whatever you choose, patience matters. The AAD says it takes at least 6 to 8 weeks before you start to see fewer breakouts. If you want a starting framework, see my simple acne routine and how long acne treatments take.

What looks like acne but isn’t?

Several conditions get mistaken for acne, and they often need different treatment. The AAD lists hidradenitis suppurativa and perioral dermatitis as common look-alikes. Another is Malassezia (Pityrosporum) folliculitis, a yeast problem nicknamed “fungal acne.” StatPearls advises clinicians to consider it when “acne” fails to respond to, or even worsens after, antibiotic treatment. If your bumps are itchy, uniform and mostly on your chest, back or hairline, read fungal acne before buying more acne products.

Does the type of acne affect scarring?

Yes. Deeper lesions carry more risk, but mild acne can scar too. In a US study of 1,972 patients across 120 dermatology practices, 43% had acne scarring, and nearly 7 in 10 of those people had only mild-to-moderate acne at the time of the visit. The researchers identified acne severity, relapsing acne, male sex and, importantly, delay before effective treatment as risk factors. Delay is the one you can actually do something about. The AAD adds that acne that goes untreated for a long time and a family history of acne scarring both raise your risk.

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