Boils and Carbuncles: Symptoms, Causes, and Treatment
Updated: 2 days ago
Medically reviewed by Dr. Baraa Alnahhal, MD · Last reviewed: October 2026
Quick Answer
A boil is a single painful, pus-filled bump from an infected hair follicle, while a carbuncle is a cluster of connected boils causing a deeper, more severe infection. Most are caused by Staphylococcus aureus. Small boils usually clear with warm compresses; larger boils and carbuncles may need incision and drainage and antibiotics for severe infections.
What the research says
After a skin abscess is drained, an antibiotic can raise the cure rate. In a randomized trial of outpatients older than 12 with an uncomplicated abscess treated with drainage, clinical cure occurred in 507 of 630 people (80.5%) given trimethoprim-sulfamethoxazole versus 454 of 617 (73.6%) given placebo (difference 6.9 percentage points; 95% CI 2.1 to 11.7; P=0.005); 45.3% of participants had MRSA-positive cultures. In the per-protocol group, the antibiotic also lowered later surgical drainage (3.4% vs 8.6%) and new skin infections at other sites (3.1% vs 10.3%) (Talan et al., N Engl J Med, 2016) [3].
The benefit held in smaller abscesses, with more side effects from one of the drugs. In 786 adults and children with an abscess 5 cm or smaller, drained and then randomized for 10 days, cure rates were 83.1% with clindamycin and 81.7% with trimethoprim-sulfamethoxazole, versus 68.9% with placebo (P<0.001 for both comparisons). Adverse events were more frequent with clindamycin (21.9%) than with trimethoprim-sulfamethoxazole (11.1%) or placebo (12.5%) (Daum et al., N Engl J Med, 2017) [4].
Both trials studied drained skin abscesses, which include many large boils. They do not apply to a small boil being treated at home with warm compresses; antibiotic decisions are for your doctor to make.
What are boils and carbuncles?
A boil is a painful, pus-filled bump that forms under your skin when bacteria infect and inflame one or more of your hair follicles. A carbuncle is a cluster of boils that form a connected area of infection under the skin.
Most boils clear up at home with warm compresses and patience. The single most important rule: never prick or squeeze a boil, because that can spread the infection. Carbuncles, boils on the face, and boils that won't heal are a different story — they need a doctor's care, and sometimes a simple in-office drainage procedure.
A boil — also called a furuncle — usually starts as a reddish or purplish, tender bump. The bump quickly fills with pus, growing larger and more painful until it ruptures and drains.
A carbuncle is a cluster of boils that form a connected area of infection under the skin. Compared with single boils, carbuncles cause a deeper and more severe infection and are more likely to leave a scar. People who have a carbuncle often feel unwell in general and may experience a fever and chills.
What are the symptoms of boils and carbuncles?
Boils can occur anywhere on your skin, but appear mainly on the face, back of the neck, armpits, thighs, and buttocks — hair-bearing areas where you're most likely to sweat or experience friction.
Signs and symptoms of a boil usually include a painful, red bump that starts out small and can enlarge to more than 2 inches (5 centimeters), reddish or purplish swollen skin around the bump, an increase in the size of the bump over a few days as it fills with pus, and the development of a yellow-white tip that eventually ruptures and allows the pus to drain out.
The carbuncle symptoms follow the same path, but run deeper and rougher: a wider connected area of infection, a higher chance of scarring, and a general feeling of being unwell, sometimes with fever and chills.
Symptom clue | What it tells you |
Small tender bump that fills with pus over a few days | Typical boil progression |
Reddish or purplish swelling around the bump | Inflamed skin around the infected follicle |
Yellow-white tip that ruptures and drains | The boil is draining naturally |
Can grow larger than 2 inches (5 cm) | Large boils may need medical drainage |
Cluster of connected bumps, fever, chills | Points to a carbuncle, not a simple boil |
When should you see a doctor for boils and carbuncles?
You usually can care for a single, small boil yourself. But see your doctor if you have more than one boil at a time, or if a boil occurs on your face or affects your vision.
Also seek care if a boil worsens rapidly or is extremely painful, causes a fever, gets bigger despite self-care, hasn't healed in two weeks, or recurs. Any boil accompanied by fever and chills in a wide, connected area of skin points to a carbuncle, which deserves professional treatment.
What causes boils and carbuncles, and who is at risk?
Most boils are caused by Staphylococcus aureus, a type of bacterium commonly found on the skin and inside the nose. A bump forms as pus collects under the skin. Boils sometimes develop at sites where the skin has been broken by a small injury or an insect bite, which gives the bacteria easy entry.
Although anyone — including otherwise healthy people — can develop boils or carbuncles, several factors increase your risk.
Risk factor | How it raises the risk |
Close contact with a person who has a staph infection | Living with someone who has a boil or carbuncle raises your odds |
Diabetes | Makes it harder for your body to fight bacterial skin infections |
Other skin conditions | Acne and eczema damage the skin's protective barrier |
Compromised immunity | A weakened immune system makes boils and carbuncles more likely |
What complications can boils and carbuncles cause if squeezed?
Rarely, bacteria from a boil or carbuncle can enter your bloodstream and travel to other parts of your body. The spreading infection, commonly known as blood poisoning (sepsis), can lead to infections deep within your body, such as your heart (endocarditis) and bone (osteomyelitis).
This is rare, but it's the reason self-surgery with a needle or a squeeze is never worth the risk — pushing the infection deeper is exactly what sends bacteria where they shouldn't go.
How are boils and carbuncles diagnosed?
Your doctor will likely be able to diagnose a boil or carbuncle simply by looking at it. A sample of the pus may be sent to the lab for testing. This may be useful if you have recurring infections or an infection that hasn't responded to standard treatment.
Many varieties of the bacteria that cause boils have become resistant to certain types of antibiotics. So lab testing can help determine what type of antibiotic would work best in your situation.
How are boils and carbuncles treated?
You can generally treat small boils at home by applying warm compresses to relieve pain and promote natural drainage.
For larger boils and carbuncles, treatment may include incision and drainage. Your doctor may drain a large boil or carbuncle by making an incision in it. Deep infections that can't be completely drained may be packed with sterile gauze to help soak up and remove additional pus.
Sometimes your doctor may prescribe antibiotics to help heal severe or recurrent infections.
Treatment | Used for | Key detail |
Warm compresses at home | Small boils | Relieves pain and promotes natural drainage |
Incision and drainage | Large boils and carbuncles | Doctor makes an incision to drain the pus |
Sterile gauze packing | Deep infections that can't fully drain | Soaks up and removes additional pus |
Antibiotics | Severe or recurrent infections | Lab-tested pus helps pick the antibiotic that works |
How can you treat a small boil at home?
For small boils, a few measures can help the infection heal more quickly and prevent it from spreading.
Warm compresses. Apply a warm washcloth or compress to the affected area several times a day, for about 10 minutes each time. This helps the boil rupture and drain more quickly.
Never squeeze or lance a boil yourself. This can spread the infection.
Prevent contamination. Wash your hands thoroughly after treating a boil. Also, launder clothing, towels, or compresses that have touched the infected area, especially if you have recurrent infections.
How can you prevent boils and carbuncles?
Boils and carbuncles cannot always be prevented, especially with a weakened immune system, though simple hygiene habits may help. But the following measures may help you avoid staph infections.
Wash your hands regularly with mild soap, or use an alcohol-based hand rub often. Careful hand-washing is your best defense against germs.
Keep wounds covered. Keep cuts and abrasions clean and covered with sterile, dry bandages until they heal.
Avoid sharing personal items. Don't share towels, sheets, razors, clothing, athletic equipment, and other personal items. Staph infections can spread via objects, as well as from person to person. If you have a cut or sore, wash your towels and linens using detergent and hot water with added bleach, and dry them in a hot dryer.
How do you prepare for your appointment?
You're likely to see your family doctor or primary care provider first, who may then refer you to a specialist in skin diseases (dermatologist) or infectious diseases.
What you can do. List all your signs and symptoms and when they first occurred. Record how long the bumps lasted and if any recurred. Make a list of all medications — including vitamins, herbs, and over-the-counter drugs — that you're taking. Even better, take the original bottles and a list of the doses and directions.
Worthwhile questions to ask include: Are tests needed to confirm the diagnosis? What is the best course of action? Is there a generic alternative to the medicine you're prescribing? Can I wait to see if the condition goes away on its own? What can I do to prevent the infection from spreading? What skin care routine do you recommend while the condition heals?
What to expect from your doctor. Your doctor is likely to ask a number of questions, such as: What did the boil look like when it first started? Are your symptoms painful? Have you had a boil or carbuncle before? Are you having fever or chills? Do you have artificial heart valves, joints, or other implanted devices?
What is the bottom line on boils and carbuncles?
Most boils are a temporary nuisance: a painful bump that fills with pus, develops a yellow-white tip, and drains on its own with the help of warm compresses and a little patience. Carbuncles — the connected clusters — and boils that show up on the face, bring a fever, or refuse to heal in two weeks are the exceptions, and those belong in a doctor's office.
The rule that protects you from the rare but serious complications is simple: don't squeeze and don't lance. The infection spreads under the skin when you force it, and that's how bacteria find their way into places they shouldn't be.
If boils keep coming back, a pus sample sent to the lab can identify exactly which antibiotic will work — an increasingly important step, since many of the bacteria behind boils have become resistant to standard treatments. And everyday habits like hand-washing, covering cuts, and not sharing towels or razors go a long way toward making sure the next boil never starts.
Next steps: See a doctor if a boil is on your face, causes a fever, worsens rapidly, grows despite self-care, hasn't healed in two weeks, or recurs.
FAQ
What's the difference between a boil and a carbuncle?
A boil is a single painful, pus-filled bump caused by an infected hair follicle. A carbuncle is a cluster of boils that form a connected area of infection under the skin, causing a deeper and more severe infection that is more likely to leave a scar and more likely to cause fever and chills.
Should I pop or squeeze a boil?
No. Popping or squeezing a boil can spread the infection into the surrounding skin and deeper tissue. The safe route is a warm compress — about 10 minutes, several times a day — which helps the boil rupture and drain on its own.
When should a boil be seen by a doctor?
See a doctor if you have more than one boil at a time, if a boil is on your face or affects your vision, if it worsens rapidly or is extremely painful, if it causes a fever, if it gets bigger despite self-care, if it hasn't healed in two weeks, or if boils keep coming back.
How are large boils and carbuncles treated?
A doctor can drain a large boil or carbuncle through a small incision. Deep infections that can't be completely drained may be packed with sterile gauze to soak up and remove additional pus, and antibiotics may be prescribed for severe or recurrent infections.
Can boils come back, and how do I prevent them?
Anyone, including healthy people, can develop boils, and people with diabetes, damaged skin from conditions like acne or eczema, or weakened immunity are at higher risk. Prevention focuses on hand-washing, keeping cuts covered with sterile bandages, not sharing towels, sheets, razors, or athletic equipment, and washing linens in hot water with bleach if you have a sore.
Disclaimer: This article is for general informational purposes only and does not constitute medical advice. Always consult a qualified health care provider for individual questions.
How long does it take for a boil to go away?
Many small boils drain and start healing on their own with warm compresses. See a doctor if a boil has not healed in two weeks or keeps getting bigger.
Are boils contagious?
The staph germs that cause boils can spread through skin contact and shared items like towels and razors. Wash your hands, keep the area covered and do not share personal items.
Should I cover a boil with a bandage?
Yes. Once a boil drains, cover it with a clean, dry bandage and change it often. This helps keep the germs from spreading.
Are boils a sign of diabetes?
Diabetes makes skin infections like boils more likely. If you get boils often, ask your provider whether you should be checked for diabetes or other immune problems.
What is the difference between a boil and a cyst?
A boil is an infected hair follicle that fills with pus and is usually red and painful. A cyst is a closed sac under the skin that is often painless unless it becomes infected.
Related Reading
Staph Infections: Symptoms, Causes, Treatment, and Prevention — Complete Guide explains the staph germs behind most boils and how to prevent spread.
What Is an MRSA Infection? A Plain-Language Guide to This Tough Staph Germ explains antibiotic-resistant staph and how it is treated.
Cellulitis: Symptoms, Causes, Diagnosis and Treatment — What You Need to Know covers a spreading skin infection that needs prompt antibiotics.
Hidradenitis Suppurativa: Symptoms, Causes, and Treatment Options explains a long-term condition that causes repeated boil-like lumps.
References
Mayo Clinic Staff. Boils and carbuncles - Symptoms and causes. Mayo Clinic. September 18, 2021. https://www.mayoclinic.org/diseases-conditions/boils-and-carbuncles/symptoms-causes/syc-20353770
Mayo Clinic Staff. Boils and carbuncles - Diagnosis & treatment. Mayo Clinic. September 18, 2021. https://www.mayoclinic.org/diseases-conditions/boils-and-carbuncles/diagnosis-treatment/drc-20353776
Talan DA, et al. Trimethoprim-Sulfamethoxazole versus Placebo for Uncomplicated Skin Abscess. N Engl J Med. 2016;374(9):823-32. PMID 26962903. https://doi.org/10.1056/NEJMoa1507476
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. https://doi.org/10.1056/NEJMoa1607033
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