Pimple vs Boil: How to Tell the Difference and What to Do
A pimple starts inside a clogged oil pore, usually stays small, and settles in three to seven days. A boil is a bacterial infection of a hair follicle, usually from staph, that grows larger, becomes very painful and fills with pus over several days. Boils are more common on the thighs, buttocks, armpits and neck, and a large or recurring one needs a doctor.
A red, sore bump appears overnight and the first question is always the same: is this just a pimple, or something worse? Pimples and boils can look alike in the first day or two, but they have different causes, behave differently, and need different care. Squeezing a boil, in particular, can spread the infection. This guide explains how to tell a pimple from a boil, how each one develops, what you can safely do at home, and the signs that mean it is time to see a doctor.
Getting pimples again and again on the face?
Our Acne Relief Serum pairs 2% salicylic acid, which clears the oil plug inside the pore, with 5% niacinamide, which helps calm redness and fade the marks pimples leave behind.
Explore the Acne Relief Serum βWhat is the difference between a pimple and a boil?
The core difference is where each one starts. A pimple begins when sebum and dead skin cells block a pore, and acne bacteria that normally live on the skin multiply inside the trapped oil. The body's response creates redness, swelling and sometimes a small white head of pus. A boil, also called a furuncle, is an infection of the hair follicle and the tissue around it, most often caused by Staphylococcus aureus. That infection forms a pocket of pus deeper in the skin, which is why a boil grows larger and hurts more than a typical pimple.
A cluster of connected boils is called a carbuncle. It is deeper, often comes with fever, and always needs medical care.
How can you tell a pimple from a boil?
| Feature | Pimple | Boil |
|---|---|---|
| Cause | Clogged oil pore, acne bacteria | Bacterial infection of a hair follicle, usually staph |
| Size | Usually under 5 mm | Starts pea-sized, can grow to 2 cm or more |
| Pain | Tender when touched | Throbbing, painful even without touching |
| How it develops | Peaks in 1 to 3 days, then settles | Grows for several days, softens, forms a yellow-white centre |
| Common locations | Face, chest, upper back | Thighs, buttocks, armpits, groin, neck, face |
| Skin around it | Small rim of redness | Wide area of red, warm, swollen skin |
| How long it lasts | 3 to 7 days | 1 to 3 weeks |
| Other symptoms | None | Sometimes fever, tiredness, swollen glands |
In short: a pimple stays small and local, while a boil grows, deepens, throbs and spreads redness around itself. If a bump keeps getting bigger after three days, treat it as a possible boil.
Is it a boil or a cystic pimple?
Cystic acne is the trickiest look-alike. A cystic pimple is a deep, painful lump that forms when a blocked pore ruptures under the skin, and it can be as sore as a boil. The differences are that cystic acne usually appears on the jaw, chin and cheeks, often comes in groups or repeats in the same zones, is driven by oil and hormones, and rarely comes to a soft yellow head that drains on its own. A boil tends to be a single lump that softens and points to a head within a week. Our guide to cystic acne explains how to manage deep breakouts, and the guide to blind pimples covers smaller under-the-skin bumps.
What causes boils?
Boils develop when staph bacteria, which many people carry harmlessly on their skin or in their nose, get into a hair follicle through a small break in the skin. Common triggers include:
- Friction and sweat from tight clothing, especially on the thighs and buttocks in hot, humid weather
- Shaving, waxing or plucking that leaves tiny nicks in the follicle
- Ingrown hairs
- Diabetes or other conditions that weaken immunity
- Close contact with someone who has a staph skin infection, or shared towels and razors
- Poor nutrition or anaemia, which can make recurrent boils more likely
Folliculitis, a milder infection that shows up as many small pus bumps around hair follicles, can turn into boils if it goes deeper. If you have small bumps on the buttocks, see our guide to folliculitis on the buttocks.
How do you treat a pimple at home?
Most pimples settle on their own in under a week, and gentle care helps them heal without leaving marks:
- Do not squeeze. Squeezing pushes debris deeper and raises the risk of a dark mark or scar. Read what happens when you pop a pimple.
- Use salicylic acid. A 2% salicylic acid serum or face wash loosens the plug inside the pore and helps prevent the next one.
- Cover a surfaced head. A hydrocolloid pimple patch protects a pimple with a visible white head and stops picking.
- Keep moisturising and use sunscreen. This helps the skin heal and stops the leftover red or brown mark from darkening.
How should you care for a boil?
A small boil often drains and heals on its own within one to three weeks. You can support that safely:
- Apply warm compresses. Hold a clean, warm, damp cloth on the boil for 10 to 15 minutes, three or four times a day. Heat increases blood flow and helps the pus come to a head.
- Never squeeze, prick or cut it. Doing so can push the infection deeper or into the bloodstream, especially on the face.
- Keep it clean and covered. Once it drains, wash gently with soap and water and cover with a sterile dressing.
- Wash your hands and do not share towels. Staph spreads by contact.
- Do not put acne products on it. Salicylic acid serums and pimple patches are made for pimples, not infected boils.
When should you see a doctor?
See a doctor promptly if any of these apply:
- The boil is on your face, especially near the nose or eyes
- It is larger than about 2 cm, extremely painful, or has not drained within a week of warm compresses
- You have fever, chills, or red streaks spreading from the lump
- Several boils appear together, or boils keep coming back
- You have diabetes, a weakened immune system, or are pregnant
A doctor may drain the boil safely under sterile conditions and may prescribe antibiotics. Recurrent boils sometimes need tests for diabetes or a staph carrier state.
How do you prevent pimples and boils?
Prevention overlaps for both. Wear breathable cotton in hot weather and change out of sweaty clothes quickly. Shave in the direction of hair growth with a clean razor. Keep your own towel. For pimples specifically, a daily salicylic acid cleanser and leave-on serum keeps pores from clogging, and niacinamide helps balance oil. If acne keeps returning in the same areas, our guide on how long a pimple lasts explains what is normal and when to escalate.
Frequently asked questions
Can a pimple turn into a boil?
Occasionally. If a pimple is squeezed or picked and staph bacteria get into the broken skin, the infection can go deeper and behave like a boil. Leaving pimples alone lowers that risk.
Should I pop a boil?
No. Squeezing or pricking a boil can spread the infection to nearby skin or deeper tissue. Use warm compresses to help it drain naturally, and see a doctor if it is large, on the face or not improving.
How long does a boil take to heal?
Most small boils come to a head and drain within one to two weeks, then heal over a few more days. Larger boils may need medical drainage.
Are boils contagious?
The staph bacteria in a boil can spread to other people or other parts of your body through touch, towels or razors. Keep it covered and wash your hands after touching it.
Why do I keep getting boils on my thighs?
Friction, sweat and tight clothing on the inner thighs create ideal conditions for follicle infection. Recurrent boils can also signal diabetes or a staph carrier state, so see a doctor if they keep returning.
Products in this guide