Cysts form when skin cells that normally shed from the surface instead move deeper into the skin, creating a small pocket that fills with a thick, protein-rich substance called keratin. This is the most common reason people develop one or more cysts on their body. The good news: most skin cysts are harmless, slow-growing, and noncancerous. Understanding what triggers them can help you figure out whether yours need attention.
How Cysts Actually Form
Your skin constantly sheds its outermost cells. Sometimes those cells migrate inward rather than flaking off. When that happens, they form a tiny sac beneath the skin’s surface. That sac becomes a cyst wall, and the trapped cells begin secreting keratin, the same protein that makes up your hair and outer skin layer. The keratin accumulates into a thick, white, toothpaste-like substance that fills the cyst from the inside.
This process can be set in motion by something as minor as a small skin injury, an irritated hair follicle, or chronic friction from clothing. Surgical scars and piercings can also push epidermal cells into deeper layers of skin, seeding a cyst that may not become noticeable for months or years.
The Most Common Types
Not all cysts are the same, even though they can look similar from the outside. The two most frequent types are epidermoid cysts and pilar cysts. Both appear as smooth, round lumps just under the skin, both grow slowly, and both contain that characteristic cheesy keratin material. The difference is where they show up and what their walls are made of.
Epidermoid cysts are lined with cells identical to your skin’s outer layer. They most commonly appear on the face, neck, chest, upper back, and sometimes the groin area. They tend to develop in adults in their 20s to 40s.
Pilar cysts are lined with cells resembling hair root tissue, and they show up almost exclusively on the scalp. They’re more common in women and typically appear in middle age. If you’ve noticed a firm bump on your scalp that catches on your comb, this is likely what you’re dealing with.
Why Some People Get More Than Others
Several factors determine whether you’re prone to developing cysts, and many of them overlap.
Hormones and Oil Production
Testosterone and other androgens directly increase sebum production in the oil glands at the base of hair follicles. When your body produces excess sebum, it can mix with dead skin cells and block follicle openings. This is the same basic process behind acne, but when the blockage goes deep enough and a closed sac forms around it, the result is a cyst rather than a pimple. Hormonal shifts during puberty, menstrual cycles, and perimenopause can all ramp up this process.
Skin Injuries and Friction
Any trauma that pushes surface skin cells below the epidermis can start a cyst. This includes cuts, scrapes, acne that was picked or squeezed, and even repeated friction from tight clothing, bra straps, or backpack straps. If you’re noticing cysts in areas where fabric presses against your skin, friction is a likely contributor.
Genetics
Some people are simply wired to develop cysts more readily. A condition called steatocystoma multiplex, caused by mutations in the KRT17 gene, leads to dozens or even hundreds of small cysts across the torso, neck, upper arms, and upper legs. These typically first appear during adolescence and are filled with oily sebum rather than keratin. The condition is inherited in an autosomal dominant pattern, meaning only one parent needs to carry the gene for you to develop it. If multiple family members have dealt with recurring cysts, genetics may be playing a role even without a formal diagnosis.
Cyst vs. Lipoma vs. Abscess
Finding a lump under your skin naturally raises concern. Here’s how to tell what you’re likely dealing with:
- Cysts feel firm, sit just under the skin, and sometimes have a visible central pore or “punctum.” They may be slightly tender but are often painless unless inflamed. If squeezed (which you shouldn’t do), they can release a thick, foul-smelling discharge.
- Lipomas feel soft and doughy, move easily when you press on them, and are almost always painless. They’re made of fat cells, not keratin. Most stay under 5 centimeters (about 2 inches) in diameter.
- Abscesses are infections. They’re red, warm, painful, and grow quickly over days rather than weeks or months. They often cause fever or general malaise.
If your lump is soft and painless, it’s more likely a lipoma. If it’s firm but slow-growing, a cyst is the most probable explanation. Rapid growth, heat, and spreading redness point toward infection.
When a Cyst Becomes a Problem
Most cysts sit quietly under the skin for years without causing trouble. They become concerning when they show signs of infection: increasing pain, redness, swelling, warmth, or discharge. A cyst that ruptures beneath the skin can trigger a strong inflammatory reaction even without bacteria being involved, causing sudden swelling and tenderness.
According to Cleveland Clinic guidelines, a cyst warrants medical evaluation if it grows rapidly, exceeds 5 centimeters in diameter (roughly the size of a golf ball), or shows signs of infection. Any lump that changes noticeably over a short period deserves a professional look.
What You Can Do at Home
You cannot make a cyst disappear on your own, and squeezing or popping it will almost certainly make things worse. Squeezing pushes the contents deeper into surrounding tissue, invites infection, and increases the chance the cyst will come back larger.
If a cyst becomes inflamed or uncomfortable, apply a warm, wet washcloth for 20 to 30 minutes, three to four times a day. Use water no hotter than a comfortable bath. This can help draw the contents closer to the surface and reduce pain. It won’t eliminate the cyst permanently because the sac lining remains intact, but it often helps manage flare-ups.
Reducing Your Risk of New Cysts
Since cysts start with trapped skin cells and clogged follicles, keeping your skin clear of buildup is the most practical preventive step. Gentle exfoliation with a washcloth, sponge, or soft brush helps remove dead cells before they can migrate inward. Chemical exfoliants containing salicylic acid can also keep pores clear, though you should introduce them gradually if your skin is sensitive.
Moisturize regularly with a noncomedogenic product, one specifically formulated not to clog pores. Dry skin is more prone to keratin buildup, so this matters especially in winter, in air-conditioned environments, or if you shower in very hot water. Switching to lukewarm showers alone can make a difference. Avoid tight, restrictive clothing in areas where cysts have appeared before, since repeated friction irritates follicles and promotes blockages.
If your cysts seem to track with hormonal cycles, that pattern is worth mentioning to a doctor. Hormonal management can sometimes reduce the frequency of new cysts in people whose breakouts are clearly tied to androgen fluctuations.
How Cysts Are Removed
If a cyst bothers you cosmetically, keeps getting inflamed, or sits in a spot where it’s constantly irritated, a doctor can remove it. The standard approach is a minor in-office procedure under local anesthesia. The key is removing the entire cyst wall. If even a small fragment of the lining stays behind, the cyst will typically refill and return. This is why home drainage or having someone “pop” it for you doesn’t work as a permanent solution.
For inflamed or infected cysts, your doctor may first treat the inflammation before attempting removal, since operating on an actively inflamed cyst makes it harder to extract the wall cleanly. Recovery from removal is straightforward for most people, involving a small wound that heals over one to two weeks with basic wound care.