Last Updated on April 17, 2026 by Giorgia Guazzarotti
If you’ve ever extracted a blackhead and immediately thought “Wait, what’s this strong cheese smell? Why do blackheads smell like cheese?,” first of all, welcome to the club, we have snacks. Seriously though, I got completely obsessed with this question a while back and went down a proper rabbit hole – peer-reviewed studies, microbiology papers, a really long Wikipedia page about a specific bacterium that I will absolutely be telling you about – and what I found was honestly so much more interesting than I expected. So that’s what this article is. Not a “here are five tips to unclog your pores” listicle. A real, actual explanation of what is happening inside your skin when you extract a blackhead, why it smells the way it does, and what the cheese comparison is doing there, because it is not a coincidence. It is embarrassingly literal.
What Is A Blackhead?
A blackhead is a mild type of acne that looks like a dark, small, non-inflamed bump on the skin’s surface. The dark bit at the top? Not dirt. The dark colour comes from oxidation – the same process that turns a cut apple brown when you leave it sitting on the counter. Here’s what’s actually going on. Your sebaceous glands produces sebum, this waxy, slightly fatty oily substance that keeps your skin moisturised and acts as a kind of protective barrier. Your skin needs it. It’s not bad.
But sometimes – especially if you have oily skin, or you’re going through a hormonal phase (puberty, pregnancy, various points in the menstrual cycle, basically any time your body decides to be dramatic), your skin produces too much oil. And when there’s too much of it, the excess oil starts mixing with dead skin cells inside the follicle and forms a little plug. That plug is a blackhead. Technically called an open comedo, which sounds vaguely like a bad improv group. The pore stays open at the top, which means the surface of the plug gets exposed to oxygen, and that’s when the oxidation happens and it turns dark. So it’s sebum, dead skin cells, and a chemical reaction with air. No dirt involved.
Related: What’s The Difference Between A Blackhead, A Whitehead, And A Pimple?
Why Do Blackheads Have A Cheesy, Unpleasant Smell?
Here’s where it gets genuinely wild and I need you to stick with me because this involves cheese manufacturers and I am not being metaphorical. The cheesy smell comes from two separate things happening at the same time inside the blocked follicle. Both of them are producing volatile compounds (i.e. compounds that evaporate easily and float directly into your face when you break the surface) and together they create that warm, sour, rancid, vaguely parmesan-like smell that you are now going to be thinking about every time you eat cheese. I’m sorry in advance.
1. Your Pore Has Bacteria In It That Literally Make Cheese
Your skin has bacteria living on it. That’s completely normal. It’s called the skin microbiome and it does good things for you. Well, most of the bacteria in the microbiome do good things for you. Some of them can cause issues. One of them, Cutibacterium acnes (used to be called Propionibacterium acnes before scientists renamed it, which feels like a very anticlimactic rebrand), is the main bacteria behind acne. It loves oxygen-free environments, which makes a clogged, sebum-filled pore its ideal home. Once it’s in there, it starts breaking down the fatty acids in your sebum to feed itself. That breakdown process is what triggers your immune system, causes inflammation, and turns a simple blocked pore into a red, angry spot.
But here’s the thing – and this is where the cheese smell comes in. As it breaks down that sebum, it produces propionic acid as a byproduct. Propionic acid is one of the primary compounds responsible for the smell of Swiss cheese. The same bacterial genus – and I really cannot stress this enough – is used in the commercial production of Emmental and Gruyère. Your pores are, in a very real and very specific sense, running a small artisanal cheese operation.
While it’s at it, the same bacteria also produces isovaleric acid, which is the specific compound behind the smell of parmesan AND sweaty feet, which tells you a lot about why those two things smell weirdly similar. These are volatile organic compounds, they evaporate the moment you break the surface, and they hit your nose all at once. The anaerobic environment makes it worse, too – anaerobic bacterial metabolism produces notably more pungent compounds than what happens in oxygen-rich environments, so the sealed-off conditions of the follicle are actively intensifying the smell.
2. The Fat In Your Pores Is Going Rancid
At the same time as the bacterial fermentation is happening, the lipids (the fats) in the sebum are also oxidising. Sebum contains unsaturated fatty acids and a compound called squalene, and when these react with oxygen at the surface of the open pore, they break down in a process called lipid peroxidation. This produces a compound called trans-2-nonenal. Which is also, delightfully, the compound responsible for what researchers politely call “aged person body odor:” it increases in the skin of older adults as antioxidant defences weaken and skin lipids oxidise more readily. Trans-2-nonenal smells greasy and rancid, a bit like rancid butter, with a grassy edge to it.
So what you’re actually smelling when you extract a blackhead is: bacterial cheese fermentation byproducts layered on top of the smell of fat going rancid. Together. Simultaneously. In one tiny pore. Your nose is picking all of that up and quite reasonably going “what IS that” and the answer is: you have a small biochemistry lab living in your face, and it’s been working very hard.
When This Unpleasant Odor Is Stronger Than Usual
Sometimes the smell is genuinely intense – like, more than just a mild “oh that’s odd” moment, more of a “I need to leave the room” situation. That usually means a few things are amplifying the process. More sebum production means more substrate for the bacteria to ferment and more fat to oxidise, so if your oil glands are in overdrive (thanks to hormones, genetics, or just the skin you were born with) everything gets more concentrated and you get a very strong smell. Young adults with acne vulgaris often notice this more intensely for exactly that reason.
The much more potent version of this whole situation is an epidermoid cyst (sometimes called a sebaceous cyst, though they’re technically different things). These form when a follicle gets completely blocked and sealed off, so nothing can escape. The bacterial fermentation inside one of these just… keeps going. For a long time. With no outlet. The material inside genuinely resembles cottage cheese – it’s pale, soft, and has a distinctive, extremely pungent smell that is a whole level above a regular blackhead. A board-certified dermatologist will tell you not to squeeze these at home because the entire sac needs to come out, often through surgical excision, otherwise they just come back. If what you’re dealing with is recurring, deep, or significantly smellier than a regular blackhead, it’s worth getting that looked at because the treatment options are quite different.
Severe acne (including acne conglobata, a particularly nasty deep-cystic form) can also produce a notably strong odor because the bacterial infections are more extensive and you start getting sulfur compounds involved, which add their own delightful top notes to the whole experience.
Best Treatment For Blackheads
- Salicylic acid is probably your best friend for blackheads specifically. It’s oil-soluble, meaning it can actually get inside the follicle and dissolve the sebum plug rather than just cleaning the surface of the skin. This is the only exfoliant who can do that. Glycolic acid and co just don’t do anything for pores or address the bad smell. This is by far the most effective treatment.
- Benzoyl peroxide goes after the bacteria directly – it releases oxygen into the follicle, which is toxic to the anaerobic C. acnes that’s running your personal cheese operation. Lower concentrations work just as well as higher ones, usually with less irritation, so don’t feel like you need to go nuclear.
- Regular cleansing – gentle cleanser, consistent, not aggressive – reduces the amount of oil and dead skin cells available to cause problems. The trap people fall into is over-washing, which strips the skin barrier and causes the oil glands to compensate by producing even more sebum. Your skin is petty like that.
In case you’re wondering, other acne treatments like tea tree oil, oral antibiotics, and retinoids generally reduce acne, but they don’t get inside the pores, so they wouldn’t be the most appropriate treatment for this. As for home remedies, don’t bother. You’re just hurting your skin.
Best skin care products with salicylic acid:
- Drunk Elephant T.L.C. Framboois Glycolic Night Serum: A lightweight serum with Glycolic Acid and Salicylic Acid to lighten dark spots and heal pimples. Available at Cult Beauty and SpaceNK
- Paula’s Choice Skin Perfecting 2% BHA Liquid Exfoliant ($29.00): The gold standard for acne exfoliation, it has a tacky texture that heals and prevents pimples. Available at Paula’s Choice and Selfridges
- The Ordinary Salicylic Acid 2%: The cheaper Salicylic Acid exfoliant out there. The texture isn’t too pleasant, but it does the job. Available at Beauty Bay and Cult Beauty
The Bottom Line
Your blackheads smell like cheese because your pores contain bacteria from the same family that makes Swiss cheese, and those bacteria have been fermenting your sebum in an oxygen-free environment, producing the exact same volatile acids that give aged cheese its smell. Plus your skin fat is oxidising on top of that. It is genuinely one of those facts that once you know it, you cannot unknow it, and I apologise for ruining both blackhead extraction and cheese for you simultaneously. You’re not dirty. It’s not poor hygiene. That foul odor is not your fault. You are just a warm, sebum-producing human being with a thriving microbial ecosystem on your face, and honestly? That’s kind of amazing.
