If you’ve ever popped a pimple (which we strongly recommend against— here’s why), you probably noticed liquid or other debris escaping from the newly opened pore. This is common with many different types of acne, but have you ever wondered exactly what is in a pimple and how it got there in the first place? And what is that stuff inside them?

If you’re looking to learn how to get rid of pus-filled pimples and why pus in pimples happens, you’ve come to the right place.

What’s inside a pimple?

So what are pimples made of? Before we can break it down, first, it’s important to understand how pimples form. A pimple starts to form when excess oil and dead skin cells clog a pore. An excess of sebum from the pore’s sebaceous gland builds up, combines with dead skin cells, and then clogs the hair follicle. Bacteria that normally live on the skin thrive in the excess sebum leading to inflammation, and voilà: A pimple is born.¹ Add to that the fact that there are several different types of pimples you might experience, which can affect what’s inside.

Non-inflammatory acne

Non-inflammatory acne comes with good news: This type of pimple is usually painless and doesn’t contain pus. The most common categories of non-inflammatory pimples are:

• Whiteheads. This type of acne is known as “closed comedones” because excess oil and dead skin cells are trapped beneath a thin layer of skin.²

• Blackheads. Blackheads are called “open comedones”, and unlike whiteheads, they’re open and exposed to the air.

Inflammatory acne

Inflammatory acne often contains pus, and it also may be painful and more prone to scarring.³ Inflammation can be triggered by several factors, including an overzealous immune reaction to the bacteria contributing to inflammatory acne.⁴

• Papules. Papules are red or pink bumps that don’t contain pus.

• Pustules. Pustules are filled with pus (hence the name). The pimple head may appear white, surrounded by a ring of redness.

• Cysts. Cysts are typically large, painful, filled with pus, and can cause scarring. 

• Nodules. These hard pimples are often called “blind pimples” because of how deep they occur below the skin’s surface. They’re often painful and can leave scars. If you’ve ever experienced a nodule, you probably know: you can’t see their head, but you can surely feel them, hence their nickname.

What is pus?

Pus is basically a mix of all the “ingredients” that clogs your pores: sebum, dead skin cells, white blood cells, bacteria, and other debris.⁵ Pus in pimples develops for a reason. The bacteria that contributes to pus-filled acne is Cutibacterium acnes or “C. acnes” for short. When this bacteria enters and thrives in a blocked follicle, it causes sebum to break down to triglycerides (a type of fat), which can irritate the skin and lead to inflammation.⁶ All of this “gunk” spills out of the pore and your body’s immune system responds by sending white blood cells and other types of immune cells to fight the bacteria.⁷ When all these factors combine, it leads to inflammatory acne lesions, like cysts and pustules, often containing pus.

Tips to help prevent pus-filled pimples

Pimples with pus can be frustrating and tempting to pop, so that’s why preventing them in the first place is always a good idea. Here are a few tips to help keep pus-filled pimples at bay. 

• Turn to benzoyl peroxide or salicylic acid. Pus-filled pimples are a type of inflammatory acne, and studies have shown both benzoyl peroxide and salicylic acid to be effective treatments.⁸ You can find both in many over-the-counter face washes and topical spot treatments.

• Leave it be. We know just as well as anybody how tempting it can be to pop a pimple. Nevertheless, take it from us: Doing so can actually make it worse, especially when it comes to bacteria that could be covering your hands. Popping acne can not only irritate it, but it can also lead you to unintentionally push the pimple’s contents further into the skin, possibly leading to even more inflammation.⁹ Acne can result in permanent scarring, which is why we always recommend resisting the urge to pop that pimple. It’s just not worth it!

• Keep calm and consistent. New acne treatments often take at least several weeks to make a noticeable improvement in your skin. So if those pus-filled pimples keep popping up after you start treatment, don’t worry; stay the course and give it time.¹⁰ If you’re using a topical acne treatment, such as an antibiotic cream or retinoid, make sure to spread the product evenly all over the acne-prone areas on your face, not just on existing blemishes. Doing so can help prevent future breakouts.¹¹

• Ask a professional. If over-the-counter treatments aren’t helping, or a pimple keeps refilling with pus, a medical provider can prescribe other treatment options such as tretinoin, topical clindamycin, isotretinoin, and others that may help clear your breakouts. Some treatments for acne may have side effects, so be sure to speak with your medical provider to know if a treatment is right for you.

Personalized skincare with Curology

We know all this info may sound overwhelming, and the truth is, any type of pimple can be challenging to treat, no matter what’s inside. A pimple on the face—or anywhere for that matter—can be distressing, but remember, acne is very common and affects adults as well as adolescents. The good news is plenty of treatment options are available, so it’s just a matter of finding the one that works best for your unique skin. That’s where Curology comes in!

Get your personalized skincare routine with Curology

Get your personalized skincare routine with Curology

Start your skin quiz

One of the easiest ways to get personalized dermatology-backed skincare is with Curology. Just take a quick skin quiz and snap a few selfies to get paired with a dermatology provider. We’ll take a look at your skin and, if Curology is right for you, send a Custom Formula with a mix of active ingredients chosen for your unique skin directly to your door—for free* (you’ll just cover $4.95 for shipping and handling), and you can try any of our recommended skincare products at no extra cost. As an online skincare platform, we’re all about making medical-grade skincare accessible to everyone, no matter where you call home. 

P.S. We did the research so you don’t have to:

1. Toyoda, M., & Morohashi, M. Pathogenesis of acne. Medical electron microscopy : official journal of the Clinical Electron Microscopy Society of Japan. (2001).

2. American Academy of Dermatology. How to treat different types of acne. (n.d.).

3. American Academy of Dermatology. How to treat different types of acne. Ibid.

4. Oakley A. Inflammatory Lesions in Acne. DermNet NZ. ( February 2014).

5. Britannica Encyclopedia. Pus. (2022 February 16).

6. Ayer, J., & Burrows, N. Acne: more than skin deep. Postgraduate medical journal. (August 2006).

7. Toyoda, M., & Morohashi, M. Pathogenesis of acne. Ibid.

8. Andrea L. Zaenglein, et al. Guidelines of care for the management of acne vulgaris. (2016, February 17).

9. American Academy of Dermatology. Pimple Popping: Why only a dermatologist should do it.( n.d.).

10. American Academy of Dermatology. 10 skin care habits that can worsen acne. Ibid.

11. American Academy of Dermatology. 10 skin care habits that can worsen acne. (n.d.).

We’re here to tell you what we know. That’s why our information is evidence-based and fact-checked by medical experts. Still, everyone’s skin is unique—the best way to get advice is to talk to your healthcare provider.

* Subject to consultation. Subscription is required. Results may vary.

Written by

Curology Team

Medically reviewed by

Donna McIntyre, NP-BC