Boils (Furuncles) - Symptoms, Causes & Treatment
By ScanSkinAI Editorial Team✓ Reviewed for medical safetyLast updated June 2026
A painful, pus-filled bump that forms under the skin when bacteria infect and inflame one or more hair follicles. Boils can occur anywhere but are most common on the face, neck, armpits, shoulders, back, and buttocks.
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Quick Answer
A boil, or furuncle, is a painful, pus-filled lump that forms under the skin when bacteria infect a hair follicle. They usually start as a small, red, tender bump that grows larger over a few days as pus collects, eventually coming to a head. Most small boils can be managed at home with warm compresses to encourage natural drainage. However, you should never squeeze or pop a boil, as this can spread the infection deeper. If a boil is large, extremely painful, or located on your face, seek medical attention.
Clinical Context
Boils (furuncles) are deep follicular infections usually caused by Staphylococcus aureus, including MRSA strains. A carbuncle is a cluster of connected boils with multiple drainage points. Boils are common, affecting about 20% of people at some point. Risk factors include nasal S. aureus carriage, diabetes, obesity, and skin-to-skin contact sports. Proper incision and drainage is the primary treatment for fluctuant boils.
Symptoms
- Red, painful bump that starts small
- Bump grows larger over several days
- Pus develops at the top (comes to a head)
- Fever if infection spreads
- Surrounding skin becomes red and swollen
- Tender lymph nodes nearby
Severity & Progression
Causes & Risk Factors
- Staphylococcus aureus bacteria (including MRSA)
- Ingrown hairs
- Splinters or debris in skin
- Damaged hair follicles
- Weakened immune system
Treatment & Management
Small boils may resolve with warm compresses applied 3-4 times daily for 20 minutes, which promotes natural drainage. Boils larger than 2cm or those that don't drain spontaneously need incision and drainage by a healthcare provider. Antibiotics are reserved for cases with surrounding cellulitis, systemic symptoms, immunocompromised patients, or facial boils. Never squeeze or puncture a boil yourself - this can spread infection.
- Warm compresses 3-4 times daily
- Incision and drainage by healthcare provider
- Antibiotics for spreading infection or high-risk cases
- Proper wound care after drainage
- Antiseptic washes (chlorhexidine)
- MRSA decolonization for recurrent cases
Red Flags & Complications
Seek medical attention if you experience any of the following:
- Spread to bloodstream (bacteremia)
- Cellulitis in surrounding tissue
- Abscess formation
- Scarring
- Recurrence in same or other locations
- Rare: endocarditis, osteomyelitis
Self-Care Tips
- Apply warm, moist compresses for 20 minutes, 3-4 times daily
- Keep area clean with antibacterial soap
- Never squeeze or pop a boil
- Cover draining boil with bandage
- Wash hands frequently
- Don't share towels or razors
When to See a Doctor
If boil is on your face (risk of brain infection), lasts more than two weeks, recurs frequently, causes fever, has red streaks extending from it, or is very painful
Frequently Asked Questions
How do I know if this bump is a boil or just a big pimple?
A boil usually begins as a firm, red, and very painful lump under the skin. Over a few days, it grows larger, softer, and more tender. Eventually, a yellowish-white center of pus forms at the top, called a head. Boils are generally larger, deeper, and significantly more painful than standard pimples, and the surrounding skin often becomes red and swollen.
What causes a boil to form?
Boils are primarily caused by Staphylococcus aureus bacteria, which can include MRSA strains. These bacteria typically live harmlessly on the skin or inside the nose but can enter the tissue through tiny cuts, scratches, or damaged hair follicles. People with diabetes, compromised immune systems, or those who frequently experience friction or ingrown hairs from shaving are at a higher risk of developing them.
Can I pop or squeeze a boil to drain the pus?
No, you should never squeeze, poke, or try to cut open a boil yourself. Doing so can push the infection deeper into your skin or cause side effects like the bacteria spreading into your bloodstream. Instead, apply a warm, moist washcloth to the area for twenty minutes, three to four times a day. This helps draw the pus to the surface so the boil can drain naturally.
What will a doctor do to treat a severe boil?
If your boil is large, highly painful, or not draining on its own, a healthcare provider might perform a small procedure called an incision and drainage. They will make a minor cut into the bump to safely clear out the pus. For severe infections, rapid spreading, or if you have a weakened immune system, they may also prescribe oral antibiotics to clear the bacteria.
When should I see a doctor about a boil?
You should seek professional medical care if the boil is located on your face or spine, as these areas have a higher risk of severe complications. Also, see a doctor if the boil does not improve after a few days, comes with a fever, is extremely painful, or if red streaks begin spreading from the bump. Multiple connected boils, known as a carbuncle, also require urgent medical attention.
How can I prevent myself from getting more boils?
Good personal hygiene is the best defense. Wash your hands frequently and clean any cuts or scrapes immediately. Avoid sharing personal items like towels, razors, or clothing that might harbor bacteria. If you shave, use clean blades to prevent ingrown hairs. For people who get boils frequently, a doctor might recommend special antiseptic body washes, like chlorhexidine, to reduce the bacteria living on the skin.
Are boils contagious to other people?
The boil itself is not contagious, but the bacteria causing it can easily spread to others. Staph bacteria can transfer through direct skin-to-skin contact or by sharing contaminated items like towels, bath water, or sports equipment. If you have a draining boil, keep it covered with a clean, dry bandage and wash your hands thoroughly after changing the dressing to protect those around you.
How can ScanSkinAI help if I think I have a boil?
ScanSkinAI can analyze a photo of your skin bump to help you understand if its visual features resemble a typical boil, a pimple, or another type of skin lesion. However, our AI is an educational screening aid, not a diagnostic tool. Since bacterial skin infections can sometimes spread quickly or require professional drainage, you should always consult a healthcare provider for an official diagnosis and treatment.
Related Conditions
Medical References
Information on this page is sourced from and verified against reputable medical resources:
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Medical Disclaimer: This information is for educational purposes only and is not intended as medical advice. The content on this page should not be used to diagnose or treat any health problem. Always consult with a qualified healthcare professional for proper medical evaluation, diagnosis, and treatment of your condition.