Cellulitis and skin abscesses are both due to bacterial infections. They may develop separately or together, and they need different treatments.

Your skin is home to about 1,000 different species of bacteria. These are usually harmless, and many are even beneficial for your skin. But sometimes, harmful bacteria can enter the deeper layers of your skin and cause an infection.

Cellulitis is one such skin infection. It causes heat, tenderness, and swelling, but it doesn’t cause pus.

A skin abscess (cutaneous abscess) is also an infection of the deeper layers of skin, but it creates a pocket of pus.

Keep reading to learn more about how these conditions are related, how they differ, and how doctors treat them.

Although they are distinct conditions, cellulitis and skin abscesses do share some symptoms, including:

Cellulitis can affect any part of your body, but it most often affects the legs. It usually starts as a small patch but can spread to cover large areas. With cellulitis, you may also have a fever, chills, and fatigue.

In contrast, a skin abscess looks like a raised, painful lump. It’s typically 1–3 centimeters across, though it can get much larger. It also has a pocket, or collection, of pus under the skin. It may or may not drain or leak on its own. Abscesses can also occur anywhere on your body, but they’re most likely to affect your groin, buttocks, armpits, or limbs.

Skin-to-skin contact with areas of infection, pus, or fluid can spread both conditions.

Who’s at risk of cellulitis or skin abscesses?

Anyone can get a skin infection, but people with the following risk factors are more likely to get one:

  • obesity or overweight
  • diabetes
  • other skin conditions
  • injuries to the skin that bacteria can pass through

You can have cellulitis, an abscess, or both — though one doesn’t necessarily cause the other.

Still, some people with cellulitis may be at higher risk of abscesses or other skin infections. Factors that increase your chances include:

Bacteria cause both conditions. But an abscess usually happens when bacteria get in through a wound or, sometimes, a hair follicle.

Doctors can usually treat one or both of these conditions with you as an outpatient.

You should contact your doctor if you have symptoms of either cellulitis or an abscess. The infection can spread or worsen without treatment.

If you have an infant under 3 months old and you see skin infection symptoms and a fever of over 100.4ºF (38ºC), contact a doctor right away.

Doctors generally treat cellulitis with antibiotics. They usually prescribe antibiotics that you take by mouth (orally), though you may need them into a vein (intravenously) if your infection is severe or won’t go away.

Doctors often treat abscesses by making an incision, or a small cut in your skin, and draining the pus. You may or may not need antibiotics after this procedure.

If you have both cellulitis and an abscess, your doctor may prescribe antibiotics and recommend incision and drainage.

Know your ABCs of skin infections:
Abscess vs. boil vs. carbuncle

Skin abscesses can sometimes look like other raised skin lumps. Here’s a review of some key differences:

  • Abscesses cause painful swelling and inflammation on top of an area filled with pus. On fair skin, they may be red. On dark skin, they can appear darker than the surrounding area.
  • Boils are infections close to the surface of the skin, near the hair follicles. They’re painful and swollen, and they have a thin layer of skin over fluid. They can look red or pink on fair skin, while they may look darker on dark skin.
  • A carbuncle is a cluster of several boils close together. They form a lump containing pus under the skin.

Here are some answers to questions you may have about cellulitis and abscesses.

What comes first, cellulitis or an abscess?

Either condition may show up first. The same or different bacteria can cause them.

Some people with cellulitis, such as those with a weakened immune system, may be more likely to develop an abscess. If cellulitis is due to antibiotic-resistant bacteria, you may also be more likely to develop an abscess.

Also, the pus from an abscess is very contagious. It contains bacteria that can cause cellulitis (or other skin infections) in you or others.

Can you drain an abscess with cellulitis?

Incision and drainage is the primary treatment for an abscess with or without cellulitis. If you have cellulitis without an abscess, a doctor will prescribe antibiotics instead.

Always seek a doctor’s care to diagnose and drain an abscess, as the pus inside contains bacteria that can spread the infection.

Do cellulitis abscesses go away on their own?

Some abscesses may drain on their own. If they are small, they may go away entirely. It’s still important to get help from a doctor to make sure you’re healing and not at risk of a more severe infection or other complications.

How long does it take for a cellulitis abscess to heal?

An abscess can take a couple of weeks to heal after treatment. If you have both cellulitis and an abscess, a doctor will prescribe antibiotics for at least 5 days.

Cellulitis and abscesses are bacterial skin infections that can develop separately or together. While both can cause tender, inflamed, and swollen patches, only an abscess will have a pocket of pus.

Doctors usually treat cellulitis with antibiotics. For an abscess, they’ll typically recommend a small cut (incision) into the skin to drain the pus. You may or may not need antibiotics afterward.

You should contact a doctor if you have symptoms of either condition. They can usually treat one or both with you as an outpatient.