by Dr. Bicheng Wu, Founder of DPhiant
Is all acne the same?
Quick answer: No. Not all acne is the same. Acne falls into two categories.¹ Non-inflammatory acne includes blackheads and whiteheads, which form from clogged pores with little immune involvement. Inflammatory acne includes papules, pustules, nodules, and cysts, which develop once bacteria trigger swelling, redness, and sometimes pain.³ We break down each type individually below.
Figure 1. Types of acne lesions³
Ever bought an acne product because your friend swore it was a ‘miracle,’ only to find it did absolutely nothing for you? Or used a pimple patch that sucked out all the gunk one time, then seemed completely useless the next? Before I got into the beauty industry, I used to think acne was just… acne.
Turns out, not all acne is the same, and what works for your friend’s blackheads might do zero for your papules.
And understanding which type you have? That’s the key to finding what actually works.
The Two Main Categories
Acne lesions fall into two categories: non-inflammatory and inflammatory.¹
Non-inflammatory lesions include blackheads and whiteheads (called comedones). These happen when your pores get clogged, but there’s no significant immune response yet.
Inflammatory lesions include papules, pustules, nodules, and cysts. This is when bacteria grow, and your immune system wants to fight back, causing swelling, redness, and sometimes pain.³
Let’s break down each type.
Non-Inflammatory Acne: Comedones
Blackheads (Open Comedones)
What they are: Blackheads are non-inflammatory acne lesions that appear as dark spots on the skin, usually black or brown.
Trust me! That dark color isn’t dirt!
What’s happening: Blackheads form when excess oil and dead skin cells block hair follicles. The pore is still open, allowing air to enter and resulting in a chemical reaction called oxidation. When the sebum (oil) in the clogged pore is exposed to air, it oxidizes and turns dark.³,⁴
Where they appear: Blackheads typically show up on areas with more oil glands, particularly the face, nose, chin, and forehead.⁴
Whiteheads (Closed Comedones)
What they are: Whiteheads appear as small bumps that are white or flesh-colored. Unlike blackheads, there’s no dark center.
What’s happening: Whiteheads form the same way as blackheads: oil, bacteria, and dead skin cells clog the pore opening. The difference is that the pore remains closed. Since there’s no exposure to air, there’s no oxidation and no dark color. The clog is trapped under a thin layer of skin.³,⁴
Where they appear: Whiteheads can develop anywhere on the body but are most common on the face, particularly the forehead, nose, and chin (the T-zone).⁴
Inflammatory Acne: When Inflammation Gets Involved
There are four types of inflammatory acne. These develop when Cutibacterium acnes bacteria (formerly called Propionibacterium acnes) proliferate in clogged pores, triggering your immune system’s response.³
Papules
What they are: Papules are small pink or red bumps, typically under 5mm in diameter. They’re tender to the touch but don’t have a white or yellow center.
What’s happening: Papules mark an intermediary stage between non-inflammatory and inflammatory lesions. Research shows they form when your immune system detects bacteria in the clogged follicle and responds with inflammation. Blood flow increases to the area, which is what causes the redness, bringing immune cells and proteins in to fight the infection. As a result, the tissue swells.³
Key characteristic: There’s no pus-filled center, the inflammation is happening deeper in the skin tissue.
Author’s note: this is exactly why most hydrocolloid pimple patches won’t do much for a papule. There’s no fluid on the surface for them to draw out.
Pustules
What they are: Pustules are inflammatory lesions that look similar to papules but have a white or yellow center filled with pus. They’re surrounded by red, irritated skin.³
It’s the kind that is SO tempting to pop! But do NOT! (Scar & Pigmentation Alert!!!) We’ll cover the science of why in an upcoming post.
What’s happening: Pustules form when your immune system fights the bacterial infection in the pore. That white or yellow center contains dead white blood cells, bacteria, and tissue debris, essentially your immune system’s cleanup crew at work.
Nodules
What they are: Nodules are large, painful bumps that develop deep under the skin. They are typically 5-10mm in diameter or larger. They’re hard to the touch and can persist for weeks or months.
What’s happening: According to studies, nodules form when the infection and inflammation extend deeper into the skin tissue. The follicular wall ruptures, releasing bacteria, oil, and dead skin cells into the surrounding dermis (the deeper layer of skin). This triggers a significant immune response.³
Scar & Pigmentation Alert! Nodular acne has a high risk of leaving permanent scars. The deeper the inflammation, the more likely it is to cause lasting damage to skin tissue.³
Cysts
What they are: Cysts are large, soft, painful bumps filled with pus. They appear as red or white lesions deep under the skin and are often larger than nodules. Both nodules and cysts are deep, painful lesions. The difference is cysts are typically filled with fluid and softer, while nodules are more solid and harder.
What’s happening: Cystic acne is the most severe form of inflammatory acne. Like nodules, the infection has gone deep, but cysts are filled with fluid and softer. It can be extremely painful.³
Scar & Pigmentation Alert! This type of acne can cause significant scarring.
It’s painful for us to read posts from people who are suffering this and expressing the impact on their mental health. If you are one of them, stay strong, acne warriors!
Most People Have Multiple Types
Most people with acne don’t have just one type. You might have blackheads on your nose, a few papules on your chin, and the occasional pustule on your forehead.
This is why you may want to consider using combination therapy, addressing multiple factors at once, rather than praying your next product or treatment will do the magic, or feel frustrated altogether.⁵
What This Matters to You
Understanding acne classification isn’t just academic, it’s practical. When you know what type of lesions you’re dealing with, you can:
- Find the appropriate care or treatment.
- Recognize when you need professional help versus what you might manage at home.
- Set realistic expectations about treatment timelines and outcomes. What works for blackheads might not touch cystic acne, and vice versa.
- Better communicate with dermatologists and understand why certain treatments are recommended for your specific situation.
- Stop blaming yourself. Research makes it clear that acne is a complex skin condition involving oil production, dead skin cell buildup, bacterial colonization, and inflammation.³ It’s not about willpower or hygiene.
When to Seek Professional Help
Here’s when you should consider seeing a dermatologist:
Definitely seek professional care:
- Nodules or cysts (deep, painful lesions)
- Acne that hasn’t responded to over-the-counter treatments after several weeks
- Acne that’s significantly impacting your quality of life
Consider professional consultation:
- Persistent inflammatory lesions (papules and pustules)
- Acne covering large areas of your body
We suggest early, and appropriate treatment can fight acne and prevent scarring.¹,⁵
Your Experience? Leave a comment below
What type of acne do you primarily deal with? Did anything in this research-based breakdown change how you think about your skin? I’d love to hear in the comments below.
FAQ
What’s the difference between a pimple and a papule?
“Pimple” is just the everyday word people use for basically any acne bump. Papule is the specific clinical term for a type of pimple: a small, tender, pink or red bump with no pus-filled center.³
Can you pop a pimple?
Technically, yes. Should you? No. Research on this specifically found that picking at lesions worsens inflammation, and it's likely to interfere with healing and raise the risk of scarring.²
Is cystic acne the same as nodular acne?
Closely related, not identical. Both are deep, painful, inflammatory lesions, but cysts are softer and filled with fluid, while nodules are harder and more solid.³
Do blackheads always turn into pimples?
Not always. Blackheads are non-inflammatory, meaning there's no active immune response yet. Research shows non-inflammatory lesions can progress into inflammatory ones once bacterial activity and inflammation set in, but that's not a given for every blackhead.³
Is acne just a teenage problem?
No. Acne persists into a person’s 20s in around 64% of cases and into their 30s in about 43%.² Adult acne is common, and nothing to feel embarrassed about.
References
- Zaenglein AL, Pathy AL, Schlosser BJ, et al. Guidelines of care for the management of acne vulgaris. J Am Acad Dermatol. 2016;74(5):945–973.
- Bhate K, Williams HC. Epidemiology of acne vulgaris. Br J Dermatol. 2013;168(3):474–485.
- Vasam M, Korutla S, Bohara RA. Acne vulgaris: a review of the pathophysiology, treatment, and recent nanotechnology based advances. Biochemistry and Biophysics Reports. 2023;36:101578.
- Ramli R, et al. Acne analysis, grading and computational assessment methods: an overview. Skin Res Technol. 2012.
- Reynolds RV, et al. Guidelines of care for the management of acne vulgaris. J Am Acad Dermatol. 2024.
Disclaimer: This article is for educational purposes only and is not medical advice. Always consult with a qualified healthcare provider for diagnosis and treatment of acne.
About
I'm a PhD scientist by training. After over a decade working in large global companies across ingredient innovation and consumer product development, I'm breaking down skincare and wellness with information from actual peer-reviewed research papers. No pseudoscience, just evidence-based education. Sign up for our newsletter and follow along on our socials: @iamDPhiant | @who.says.i.cannot
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