What Is It?
Boils are painful, pus-filled lumps that form under the skin when bacteria infect and inflame a hair follicle. They are also called furuncles.
A boil is a type of skin abscess that usually starts around a hair follicle. It often appears as a red, swollen, tender lump that may grow larger before softening or draining.
Most small boils are not dangerous, but they can be uncomfortable and may spread if squeezed, picked, or not kept clean. A group of connected boils is called a carbuncle, which is usually more serious and needs medical assessment.
Boils often develop over a few days. They may start as a tender red or darker lump, then become larger, warmer, softer, and filled with pus. They often appear on areas with hair, friction, or sweating, such as the neck, armpits, thighs, buttocks, groin, or face.
Boils are usually considered when there is a painful lump centred around a hair-bearing area, especially if it becomes swollen, warm, or pus-filled. Other conditions can look similar, including acne cysts, infected insect bites, folliculitis, infected cysts, hidradenitis suppurativa, cellulitis, or other skin infections.
Why Boils Are So Common
Boils are common because bacteria can live harmlessly on the skin or inside the nose, but may cause infection if they enter a hair follicle through tiny cuts, friction, scratching, shaving, or irritated skin.
People often search for boils because the lump can be painful, swollen, and worrying. It may be difficult to tell whether it is a pimple, insect bite, cyst, boil, or deeper skin infection.
What Causes It?
Boils are usually caused by bacteria, commonly Staphylococcus aureus, entering a hair follicle and causing a deeper infection. The body responds with inflammation and pus formation.
Common Causes and Risk Factors
Skin friction or irritation
Tight clothing, sweating, shaving, or repeated rubbing can irritate hair follicles and increase the chance of boils.
Small cuts or scratched skin
Bacteria may enter through minor breaks in the skin, including scratches, insect bites, or eczema-damaged skin.
Poor drainage or blocked follicles
Blocked or inflamed hair follicles can become infected and develop into deeper, painful lumps.
Close contact or shared items
Boils may spread through skin contact or shared towels, razors, clothing, or gym equipment if hygiene is poor.
Health and immunity factors
Diabetes, weakened immunity, obesity, recurrent skin infections, or long-term skin conditions can increase the risk of boils or complications.
In some cases, recurrent boils may involve resistant bacteria, which needs medical assessment.
Boils are different from simple pimples. Pimples are usually smaller and more superficial, while boils are deeper, more painful, and often form a larger pus-filled lump.
What Should You Do?
If a boil is small and mild, first avoid squeezing, picking, or piercing it. This can push infection deeper, spread bacteria, and increase scarring.
Boils on the face, especially around the nose or upper lip, should be assessed because infections in this area can occasionally be more serious.
What to Observe First
Pay attention to:
- How long the lump has been present
- Whether it is growing, softening, or becoming more painful
- Whether there is pus, spreading redness, warmth, or swelling
- Whether there is fever or feeling unwell
- Whether there are multiple boils or recurring boils
- Whether the boil is on the face, spine, groin, or near sensitive areas
- Whether diabetes, weakened immunity, or long-term illness may be relevant
How to Tell If It Is Mild, Moderate, or Severe
Mild boils may be small, localised, and tender without fever, spreading redness, or severe pain.
Moderate boils may become larger, more painful, pus-filled, or interfere with sitting, walking, work, school, or sleep.
Severe or complicated boils include multiple boils, a carbuncle, spreading redness, fever, severe pain, boils on the face or spine, or boils in people with diabetes or weakened immunity.
How Is It Usually Managed?
Boils are usually managed by keeping the area clean, avoiding squeezing, reducing spread, and monitoring for worsening infection. A warm compress may help comfort and natural drainage, but it should be clean, gentle, and not too hot.
Avoid heat if redness is spreading quickly, pain is severe, or the person has fever. Avoid sharing towels, razors, or clothing while the boil is draining.
A pharmacist can help assess whether the lump sounds like a simple boil or whether medical review is safer. Pharmacist advice is useful if the boil is small but uncomfortable, recurring, or difficult to distinguish from an insect bite, cyst, folliculitis, or cellulitis.
Ask a Pharmacist If Unsure
Ask a pharmacist if the boil is small, mild, and you are unsure what it is.
Seek medical advice earlier for children under 12 years old, adults aged 65 years and above, pregnant women, people with diabetes, weakened immunity, recurrent boils, or boils on the face, spine, groin, or near the genitals.
When to See a Doctor
See a doctor if a boil is linked with:
- Fever or feeling unwell
- Severe or worsening pain
- Spreading redness, warmth, or swelling
- Red streaks from the area
- A boil on the face, spine, groin, or near the genitals
- A group of boils or carbuncle
- Recurrent boils
- A boil that does not improve after 1 to 2 weeks
- Diabetes, weakened immunity, or long-term illness
- Symptoms in a child under 12 years old
Quick Summary
- Boils are painful, pus-filled lumps caused by infection of a hair follicle.
- A boil is a type of skin abscess and is also called a furuncle.
- They often develop over a few days and may grow before draining.
- Do not squeeze, pick, or pierce a boil.
- Seek medical advice for fever, spreading redness, severe pain, recurrent boils, carbuncles, face-area boils, or high-risk people.
FAQ
What is a boil?
A boil is a painful, pus-filled lump under the skin caused by bacterial infection of a hair follicle.
Is a boil the same as a skin abscess?
A boil is a type of skin abscess that usually starts around a hair follicle. Other abscesses may form in different ways or deeper tissues.
Are boils serious?
Small boils are often not serious, but boils can become more concerning if they are large, painful, spreading, recurrent, or linked with fever or high-risk health conditions.
Are boils contagious?
Boils can spread bacteria through skin contact, pus, or shared items such as towels and razors. Keeping the area clean and covered helps reduce spread.
How long does a boil last?
A boil often develops over a few days. If it does not improve after 1 to 2 weeks, or keeps returning, it should be assessed.
Why do boils keep coming back?
Recurrent boils may be linked to skin bacteria carriage, friction, diabetes, eczema, weakened immunity, shared items, or close-contact spread. Medical assessment may be needed.
Should I squeeze a boil?
No. Squeezing or piercing a boil can spread infection, worsen inflammation, and increase the risk of scarring.
When should I see a doctor for a boil?
See a doctor if there is fever, severe pain, spreading redness, red streaks, recurrent boils, a carbuncle, a boil on the face or spine, diabetes, weakened immunity, or symptoms in a child under 12 years old.