Abscess
An abscess on the forearm. The skin is red, tight and shiny, and the centre is coming to a yellow point.
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Dermapedia / CompareConditions
Abscess vs Cyst
An abscess is an active infection that needs draining. It comes up over a few days, hurts on its own, and keeps growing until the pus is let out.
A cyst is a slow, painless lump that only hurts if it bursts or gets infected. It can sit under the skin for months or years without changing. Speed and pain separate the two more reliably than anything else you can see.
At a glance
| The difference | Abscess | Cyst |
|---|---|---|
| What it is | A pocket of pus. Bacteria get under the skin, most often Staphylococcus aureus . Your immune system walls them off, and the walled-off space fills with pus. It is an active infection. | A pocket of skin material. A sac forms from a hair follicle and slowly fills with keratin, the protein your skin and nails are made of. Nothing is infected. Many people call it a sebaceous cyst. That name is loose: most of these cysts hold keratin, not oil. |
| How it feels | Hot and very tender | Firm and usually painless |
| Do you feel unwell | Sometimes | No |
| Treatment | Drain it. A clinician numbs the skin, opens the pocket and lets the pus out. Relief is usually quick. Draining is the main treatment, and antibiotics do not replace it. Two trials randomly assigned patients to an antibiotic or a placebo after draining, which is the fairest way to compare two treatments. In the first, about 80% of people were cured with trimethoprim-sulfamethoxazole, against about 74% on placebo. In the second, about 83% were cured with clindamycin, 82% with trimethoprim-sulfamethoxazole and 69% on placebo. So an antibiotic adds a real but modest amount on top of draining. | Remove the whole sac. A cyst that does not bother you can be left alone. If you want it gone, the sac needs to come out in one piece, and that is easiest when the area is calm rather than inflamed. Emptying the contents leaves the lining behind, and the lining goes on making keratin. |
Cyst
A cyst on the shoulder. Skin-coloured, dome-shaped, with a tiny dark dot in the centre called a punctum.
Side by side
The differences that matter
What it is
Abscess
A pocket of pus. Bacteria get under the skin, most often Staphylococcus aureus. Your immune system walls them off, and the walled-off space fills with pus. It is an active infection.
Cyst
A pocket of skin material. A sac forms from a hair follicle and slowly fills with keratin, the protein your skin and nails are made of. Nothing is infected. Many people call it a sebaceous cyst. That name is loose: most of these cysts hold keratin, not oil.
How fast it appeared
Abscess
Days
An abscess comes up quickly, often over two to five days, and keeps getting worse.
Cyst
Months to years
A cyst grows slowly. Many people say it has been there for ages and only recently started to bother them.
How it feels
Abscess
Hot and very tender
Warm to the touch and painful even without pressing. As it fills, the centre goes soft and squishy. Doctors call that fluctuance. It feels like a small water balloon under the skin.
Cyst
Firm and usually painless
Firm or rubbery, and it rolls under your finger when you push it. Most cysts do not hurt at all.
The skin over it
Abscess
Red, shiny and tight
The skin is stretched and angry-looking. It may come to a yellow or white point in the middle as it gets ready to drain.
Cyst
Normal, often with a dark dot
Skin colour or slightly yellow. Look closely for a tiny dark opening in the centre, called a punctum. That dot is the old follicle, and it points strongly to a cyst.
Do you feel unwell
Abscess
Sometimes
A larger abscess can bring fever, chills or a run-down feeling. Redness may spread outward into the skin around it.
Cyst
No
A cyst is a local problem. It does not make you feel ill anywhere else.
The at-home or drugstore version
Abscess
A warm compress, and that is all
A warm, damp cloth held on for about 10 minutes a few times a day can ease the pain. It may help a small abscess come to a head and drain by itself. It will not treat one that is large, spreading or making you feel unwell. Drawing salves are not the answer either. Ichthammol has never been tested against abscesses in a proper trial. Black salve, which contains bloodroot or zinc chloride, burns through living skin, and the FDA warns people not to use it.
Cyst
A warm compress does very little
Heat can take the edge off a cyst that has flared. It cannot empty a sac or dissolve keratin, so a quiet cyst is unchanged by anything you can buy.
Treatment
Abscess
Drain it. A clinician numbs the skin, opens the pocket and lets the pus out. Relief is usually quick. Draining is the main treatment, and antibiotics do not replace it. Two trials randomly assigned patients to an antibiotic or a placebo after draining, which is the fairest way to compare two treatments. In the first, about 80% of people were cured with trimethoprim-sulfamethoxazole, against about 74% on placebo. In the second, about 83% were cured with clindamycin, 82% with trimethoprim-sulfamethoxazole and 69% on placebo. So an antibiotic adds a real but modest amount on top of draining.
Cyst
Remove the whole sac. A cyst that does not bother you can be left alone. If you want it gone, the sac needs to come out in one piece, and that is easiest when the area is calm rather than inflamed. Emptying the contents leaves the lining behind, and the lining goes on making keratin.
Does it come back
Abscess
Usually not
Once it has been properly drained, an abscess generally settles. Abscesses that keep returning in the armpits, groin or under the breasts may be hidradenitis suppurativa, which is a different condition and needs its own plan.
Cyst
Yes, if any sac is left
Reviews of cyst surgery consistently report less recurrence when the whole wall is taken out than after drainage alone. Reported rates vary a lot by technique, so there is no single number to quote.
Is it a cyst or an abscess?
Abscess
- Timing — Came up over days and is still changing.
- Pain — Hurts on its own, not just when pressed. Hot to the touch.
- Centre — Skin is red and tight, and may be pointing yellow or white.
Cyst
- Timing — Has been there for months or years, growing slowly.
- Pain — Usually painless. Firm, and moves when you push it.
- Centre — Normal-coloured skin, often with a tiny dark dot in the middle.
The one that fools everyone
Cyst
A flared cyst is frequently not infected. The keratin inside leaks into the surrounding tissue and the body attacks it as if it were a splinter. That reaction produces the same redness, swelling and pus-like material as an infection, with no bacteria driving it. Bacteria grown from inflamed cysts are much the same as those found in calm ones.
Two clues point back towards a cyst. There was a lump in that exact spot before it flared, and there is a dark punctum in the centre. Mention either one to whoever sees you, because the sac will still need removing once things settle.
Common questions
Questions Patients Ask
Is it a cyst or an abscess?
Check the speed and the pain. A lump that appeared this week and throbs on its own is more likely an abscess. A lump that has been there for months, feels firm, does not hurt and has a tiny dark dot in the centre is more likely a cyst.
Cyst vs abscess — what is the difference?
A cyst is a sac of skin material that built up slowly and is usually painless. An abscess is a pocket of pus your body walled off around bacteria, and it comes on fast, red and sore. Draining an abscess fixes it. Draining a cyst does not, because the sac stays behind and refills.
Can a cyst turn into an abscess?
A cyst can become infected, yes. More often, a cyst that suddenly turns red and painful has burst under the skin rather than caught an infection. Both look the same from the outside, so they are often treated the same way at first.
Can I pop it myself?
No. Pressing on a closed pocket pushes its contents deeper into tissue instead of out. An unsterile needle can put bacteria into the pocket. With a cyst, the sac wall stays behind anyway, so it refills.
Do drawing salves work?
There is no trial evidence that ichthammol drains an abscess. Black salve is worse than useless: it contains bloodroot or zinc chloride, it burns through living skin, and the FDA warns against it.
Does an abscess need antibiotics?
Draining it is the main treatment. Trials show antibiotics taken after draining add a modest benefit, raising cure rates by roughly 7 to 14 percentage points. Doctors are most likely to add them when redness is spreading, you have a fever, or your immune system is weak.
Will it go away on its own?
A small abscess sometimes drains by itself, and warm compresses can help it along. A cyst will not go away on its own. It may shrink after a flare, but the sac stays.
Why does my cyst keep coming back after being drained?
Draining empties the contents but leaves the lining behind, and the lining goes on making keratin. Taking the whole sac out is what stops it returning.
Does removing a cyst leave a scar?
Yes, any procedure leaves a small scar. Removal is easier and the scar is usually smaller when it is done while the cyst is calm rather than during a painful flare.
When should I get seen urgently?
Go the same day if you have a fever, if the redness is spreading or streaking away from the lump, if it is growing by the hour, if it is on your face near your nose or eyes, or if you have diabetes or a weak immune system.
Safety to keep in mind
- Talan DA, et al. Trimethoprim–sulfamethoxazole versus placebo for uncomplicated skin abscess. N Engl J Med. 2016;374(9):823–832. PMID 26962903.
- Daum RS, et al. A placebo-controlled trial of antibiotics for smaller skin abscesses. N Engl J Med. 2017;376(26):2545–2555. PMID 28657870.
- Moran GJ, et al. Methicillin-resistant S. aureus infections among patients in the emergency department. N Engl J Med. 2006;355(7):666–674. PMID 16914702.
- Talan DA, et al. Comparison of Staphylococcus aureus from skin and soft-tissue infections in US emergency department patients, 2004 and 2008. Clin Infect Dis. 2011;53(2):144–149. PMID 21690621.
- Stevens DL, et al. Practice guidelines for the diagnosis and management of skin and soft tissue infections: 2014 update by the Infectious Diseases Society of America. Clin Infect Dis. 2014;59(2):e10–e52.
- Zuber TJ. Minimal excision technique for epidermoid (sebaceous) cysts. Am Fam Physician. 2002;65(7):1409–1412.
- US Food and Drug Administration. Products claiming to cure cancer are a cruel deception — consumer warning on black salve.