The hard stuff inside a pimple, especially the white or yellowish center, is pus, a mix of dead skin cells, oil (sebum), bacteria (like C. acnes), and white blood cells, which are your body's immune response to infection. For deeper, harder bumps (nodules or cysts), it's a buildup of this inflammatory gunk deep within the skin, while blackheads are oxidized sebum and dead skin forming an open plug.
Known also as cystic acne, hard pimples arise when skin pores become clogged with oil, dead skin cells, and bacteria. This blockage, occurring deep within the hair follicle, leads to infection and inflammation, forming a hard lump beneath the skin's surface.
You may be tempted to pop this unwanted guest, but it's not a good idea. Contrary to what pimple popping videos may show, squeezing your skin to extract the contents of a pimple — a mixture of oil, dead skin and bacteria — can cause scarring and infection.
Pimples refill after popping because you often don't remove all the pus and debris, pushing some deeper, while the inflammation continues, and the pore wall itself can be damaged, allowing oil (sebum) and dead cells to collect again, leading to recurrence in the same spot. Popping also creates an opening for bacteria, causing more inflammation and new pimples nearby.
If you have a hard pimple under your skin that won't go away, the odds are you have a cyst. Like with any blockage, a clogged pore can cause real inflammation, particularly of the hair follicle, making for hard and painful pimples.
Over time, the inflammation subsides, and the pimple either comes to a head and drains on its own or is reabsorbed by the body.
You've probably heard that squeezing or picking at a pimple is not a great idea, and the same goes for sebum plugs. By squeezing, you can push the contents deeper into the skin or break the pimple open, which allows the bacteria inside the pimple to spread and any bacteria on your hands to enter the pore.
Symptoms of keratin plugs include small bumps, usually on the upper arms, butt, thighs or cheeks. You might mistake a keratin plug for acne. But they aren't the same as pimples. They often develop in clusters or groups and feel rough (like sandpaper) when you touch them.
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Various at-home treatments can help to resolve hard pimples, including topical creams with benzoyl peroxide or salicylic acid, warm compresses to encourage the pimple to surface, and ice packs to reduce swelling and pain.
Hard pimples, also known as a nodule or cyst, are the result of dead skin cells or bacteria getting under the skin.
Milia (singular: milium) are small keratin-filled cysts that form just beneath the surface of the skin. Unlike acne or whiteheads, they're not caused by clogged pores or bacteria. Instead, milia develop when dead skin cells become trapped instead of naturally exfoliating—creating hard, pearl-like bumps under the skin.
For example, if when the pore starts to widen, oxygen enters and oxidizes the sebum, it can turn it black and produce a blackhead. Or, Dr. Palep explains that sebum can also combine with dead skin cells to become an attractor for P acnes bacteria that live on the hair follicle.
Milia are small white seed looking bumps. They are different than blind pimples because you can see the hard rice looking “seed” of packed keratin inside them. This is because they are closer to the skin's surface than an inflammatory acne papule is.
Sebaceous hyperplasia appears as small, shiny, spongy bumps on the surface of the skin. Usually they appear on the face, but they could develop anywhere on the body. The bumps may be a similar color to the surrounding skin, or slightly pink or yellow. They may also have a small indentation in the middle.
Squeezing also can lead to scabs and might leave you with permanent pits or scars. Because popping isn't the way to go, patience is the key. Your pimple will disappear on its own, and by leaving it alone you're less likely to be left with any reminders that it was there.
The body's immune system responds by sending white blood cells to the affected area, resulting in redness, swelling, and the formation of pus. Over time, the pimple may either burst, allowing the pus to drain out, or it may resolve on its own as the inflammatory response subsides.
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On the other hand, bumps caused by STDs, like herpes sores or genital warts, are often accompanied by pain, itching, or changes in appearance, and they tend to appear near the vulva, vagina, and anus.
The other half of the pus gets sucked inside since you're putting pressure when you release. It just stays there. You can't get it out anymore because it's inflamed and irritated. That's why pimples come back on the same spot, sometimes bigger than the one before it.”
Foods that cause your blood sugar to rise quickly, such as white bread and fries, may worsen acne.