Last updated on April 17, 2026 by Giorgia Guazzarotti
If you’ve ever popped a blackhead and immediately wondered, “Wait, what’s that strong cheesy smell? Why do blackheads smell like cheese?”, first of all, welcome to the club, we have snacks. However, seriously, I became completely obsessed with this question a while back and went down a proper rabbit hole – peer-reviewed studies, microbiology papers, a very long Wikipedia page about a specific bacterium that I will definitely tell you about – and what I found was honestly a lot more interesting than I expected. So this is what this article is about. This is not a “five tips to unclog your pores” list. A real, real explanation of what’s happening inside your skin when you pop a blackhead, why it smells the way it does, and what the cheese comparison is doing in there, because it’s no coincidence. It’s embarrassingly literal.
What is a blackhead?
Blackheads are a mild type of acne that appear as dark, small, non-inflamed bumps on the surface of the skin. Bit dark at the top? Not dirt. The dark color comes from oxidation – the same process that turns cut apples brown when left out on the counter. What’s really going on here. Your sebaceous glands produce sebum, a waxy, slightly fatty oily substance that keeps your skin moisturized and acts as a type of protective barrier. Your skin needs it. it’s not bad.
But sometimes — especially if you have oily skin, or you’re going through hormonal phases (puberty, pregnancy, various points of the menstrual cycle, basically any time your body decides to be dramatic), your skin produces too much oil. And when its quantity becomes too much, the excess oil starts mixing with the dead skin cells inside the follicle and forms a small plug. That plug is a blackhead. Technically it’s called Open Comedo, which sounds vaguely like a bad improv group. The pore is open at the top, meaning the surface of the plug is exposed to oxygen, and that’s when oxidation occurs and it turns black. So it’s a chemical reaction with sebum, dead skin cells and air. No mess involved.
Connected: What is the difference between blackhead, whitehead and pimple?
Why do blackheads have a cheesy, unpleasant smell?
This is where it gets really wild and I need you to stick with me because there are cheese makers involved and I’m not being metaphorical. The cheesy smell comes from two different things happening at the same time inside the blocked follicle. Both of these are producing volatile compounds (i.e. compounds that easily evaporate and float straight to your face when you break the surface) and together they produce that warm, sour, stale, vaguely Parmesan-like smell that you’ll now think of every time you eat cheese. I’m sorry already.
1. There are bacteria in your pores that literally make cottage cheese
Bacteria live on your skin. This is absolutely 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 problems. One of them, Cutibacterium acnes (it was called Propionibacterium acnes before scientists renamed it, which feels like a very anticlimactic rebrand), is the main bacteria behind acne. It prefers oxygen-free environments, making clogged, sebum-filled pores its ideal home. Once it gets there, it starts breaking down the fatty acids in your sebum for nourishment. That breakdown process triggers your immune system, causes inflammation, and turns a simple blocked pore into a red, angry spot.
But the thing is – and that’s where the cheese smell comes from. As it breaks down that sebum, it produces propionic acid as a byproduct. Propionic acid is one of the primary compounds responsible for the odor of Swiss cheese. The same bacterial genus – and I really cannot emphasize this enough – is used in the commercial production of Emmental and Gruyère. Your holes are, in a very real and very specific sense, running a small artisan cheese operation.
While that happens, 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 strangely similar. These are volatile organic compounds that evaporate as soon as you break the surface, and they hit your nose all at once. The anaerobic environment makes it even worse – anaerobic bacterial metabolism produces notably more pungent compounds than oxygenated environments, so the sealed conditions of the well are actively intensifying the odor.
2. The fat in your pores is getting worse
At the same time that bacterial fermentation is taking place, the lipids (fats) in the sebum are also being oxidized. Sebum contains unsaturated fatty acids and a compound called squalene, and when these react with oxygen on the surface of the open pore, they break down in a process called lipid peroxidation. This produces a compound called trans-2-nonenal. Which, happily, is the compound responsible for what researchers politely call “older person body odor”: It increases in the skin of older adults as antioxidant defenses weaken and skin lipids become more easily oxidized. Trans-2-nonenal smells sticky and rancid, somewhat like rancid butter, with a grassy edge.
So what you actually smell when you pop a blackhead is this: bacterial cheese fermentation byproducts layered on top of the smell of fat going rancid. Together. simultaneously. In a small hole. Your nose is picking up on all that and quite appropriately going “what’s that” and the answer is: There’s a little biochemistry laboratory on your face, and it’s working very hard.
When this unpleasant odor is more intense than usual
Sometimes the smell is really intense – like, more than a mild “oh that’s weird” moment, more of a “I need to leave the room” situation. This usually means that something is speeding up the process. More sebum production means more substrate for bacterial fermentation and more fat to oxidize, so if your oil glands are in overdrive (thanks to hormones, genetics, or just the skin you were born with) everything becomes more concentrated and you smell a lot stronger. Young adults suffering from acne vulgaris often notice it more intensely for this reason.
A much more powerful version of this whole condition is an epidermoid cyst (sometimes called a sebaceous cyst, although they are technically different things). These form when the follicle becomes completely blocked and closed, so nothing can escape. Inside one of these, the bacterial fermentation just… goes on. For a long time. Without any outlet. The substance inside actually looks like cheese – it’s yellow, soft, and has a distinctive, extremely pungent odor that’s a notch above regular blackheads. A board-certified dermatologist will tell you not to squeeze these out at home because the entire sac often has to come out through a surgical incision, otherwise they come back. If what you’re dealing with is recurring, darker, or has a significantly heavier odor than a regular blackhead, it’s worth looking into it as the treatment options are quite different.
Severe acne (including acne conglobata, a particularly nasty deep-cystic form) can also produce a noticeably stronger odor as the bacterial infections become more widespread and you start to get sulfur compounds involved, which add their own delightful top notes to the whole experience.
Best treatment for blackheads
- salicylic acid Possibly your best friend especially for blackheads. It’s oil soluble, meaning it can actually go inside the follicle and dissolve the sebum plug rather than just clearing the skin’s surface. This is the only exfoliant that can do this. Glycolic acid and co do nothing for pores or solve bad odor. This is the most effective treatment so far.
- benzoyl peroxide Goes straight after the bacteria – it releases oxygen into the follicle, which is toxic to the anaerobic C. acnes that is running your personal cheese operation. Lower concentrations work just as well as higher concentrations, usually with less irritation, so don’t feel like you need to go nuclear.
- regular cleaning – Gentle cleanser, consistent, not aggressive – reduces the amount of oil and dead skin cells available to cause problems. People fall into the trap of over-washing, which wears down the skin barrier and causes the oil glands to compensate by producing even more sebum. Your skin is already thin.
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 it. As far as home remedies are concerned, don’t worry. You are just damaging your skin.
Best skin care products containing salicylic acid:
- Cons of Drunk Elephant TLC Framboise Glycolic Night Serum: A lightweight serum with glycolic acid and salicylic acid to lighten dark spots and heal pimples. is available cult beauty And spacenk
- Paula’s Choice Skin Perfecting 2% BHA Liquid Exfoliant ($29.00): The gold standard for acne removal, it has a sticky texture that heals and prevents acne. is available Paula’s Choice And selfridges
- Simple Salicylic Acid 2%: The cheapest salicylic acid exfoliant out there. The texture is not very pleasant, but it works. is available beauty bay And cult beauty
bottom line
Your blackheads smell like cheese because your pores contain bacteria from the same family that make Swiss cheese, and those bacteria are fermenting your sebum in an oxygen-free environment, producing exactly the same volatile acids that give old cheese that smell. Apart from this, the fat in your skin is getting oxidized. It’s really one of those facts that once you know it, you can’t unknow it, and I’m sorry for ruining both blackhead extraction and cheese all together for you. You are not dirty. This is not bad hygiene. That smell isn’t your fault. You’re just a hot, sebum-producing human being with a thriving microbial ecosystem on your face, and honestly? It’s kind of amazing.
