Boil vs. Pimple: Signs, Causes, and Treatments for Each

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Boils and pimples can start out looking the same but will start to look and feel differently over time.

A boil, also known as a furuncle, is an infected hair follicle most often caused by a bacteria known as Staphylococcus aureus. Although S. aureus commonly resides on the skin, it can sometimes enter underlying tissues through a break in the skin.

A pimple, caused by acne, develops when a hair follicle is blocked by dead skin cells and a skin oil called sebum. The blockage allows bacteria naturally residing in the follicle to grow, forming a pus-filled pocket known as a pustule. Cutibacterium acnes is the bacteria closely associated with acne.

These characteristics account for differences in the appearance of boils and pimples.

What Does a Boil Look Like?

A boil starts as a painful, firm, red lump under the skin. Over the course of several days, the lump can grow larger, soften, and develop a pus-filled head.

Unlike a pimple, a boil can sometimes grow as large as a golf ball and start to ooze pus and clear fluid. The infection can also spread beyond the follicle to adjacent tissues, occasionally leading to a more serious infection known as cellulitis.

It is also possible to have several boils that gradually converge under the skin to form a larger, pus-filled pocket known as a carbuncle.

What Does a Pimple Look Like?

Because a pimple a limited to the hair follicle, it tends to cause a smaller, pus-filled bump that can be red, warm, swollen, and sometimes painful.

While several pimples may be situated closely together, they don't converge into larger bumps the way that furuncles do.

Cystic acne is a type of acne easily confused with boils because the pimples are generally larger and can ooze pus on their own. Regular pimples won't ooze unless they are intentionally or accidentally "popped."

Most common pimples range from the size of a nail head to the size of a pea. Cystic acne pimples may grow as large as a dime.

Location

Boils are caused by the infiltration of bacteria into hair follicles. Pimples are caused by the blockage of a hair follicle that traps bacteria inside. These characteristics inform where boils and pimples are most likely to be located on the body.

Where Are Boils Likely to Be?

Furuncles tend to develop in high-moisture areas of skin where S. aureus is more likely to proliferate and/or where hairy areas of skin rub together and create friction.

Common sites for boils include:

• Groin
• Thighs
• Breasts
• Armpits

Where Are Pimples Likely to Be?

Pimples tend to develop in areas of skin where sebum-producing glands, called sebaceous glands, are densely situated. The most common include:

• Face
• Back
• Upper chest
  

Treatment

Boils often require aggressive treatment to clear the infection and prevent them from getting worse. Pimples often require prolonged treatment to control the underlying mechanisms that give rise to acne.

How Are Boils Treated?

Boils can often be treated at home over several days. This involves draining the pocket of pus to allow healing. You can do this by covering the boil with a warm, damp cloth several times a day to soften the skin and promote drainage.

You should never lance or "pop" a boil as it can force pus into deeper layers of skin and make the infection worse.

If a boil is large and fails to respond to home treatment, you should see a healthcare provider (such as a dermatologist) who can drain the boil for you. The same is true if you have multiple boils.

A healthcare provider may also opt to prescribe antibiotics if the boil is large, recurrent, or situated in sensitive areas such as in the ears or nostrils.

How Are Pimples Treated?

Pimples can also be treated at home with gentle skin care and over-the-counter (OTC) topical medications like benzoyl peroxide and salicylic acid.

As with boils, you should never "pop" a pimple as doing so can rupture the follicle and force pus into deeper tissues.

Sometimes treatment can go on for months and require ongoing care. If these at-home measures don't help, you may need to see a dermatologist who can prescribe topical or oral drugs along with specialist procedures.

Treatment options include:

• Aldactone (spironolactone)
• Differin gel (adapalene)
• Tazorac cream (tazarotene)
• Retin-A cream (tretinoin)
• Winlevi (clascoterone)
• Birth control pills
• Steroid skin injections
• Oral corticosteroids (steroids)
• Accutane (isotretinoin)
• Laser therapy
• Chemical peels
• Surgical removal of large cysts

A big pimple under the skin may be a type of acne called nodular acne. Nodular acne requires a prescription from a healthcare provider since OTC drugs are usually not strong enough.

Antibiotics may also be prescribed if a secondary infection has occurred or you are at risk of infection due to a severe acne breakout.

When to Contact a Healthcare Provider

Severe furuncles or pimples may not respond to home therapy and require the care of a dermatologist. There are several ways to know when a dermatologist is needed.

Seeking Care for a Boil

You don't usually need to see a healthcare provider for a boil is small. Most will burst and heal on their own.

However, you should seek medical treatment for a boil if:

• It is on your face, nose, or spine.
• It doesn't heal within two weeks.
• It is large and painful.
• You develop a fever, chills, or other signs of a severe infection.
  

Seeking Care for a Pimple

Most people will opt to treat pimples at home and only see a healthcare provider when OTC treatments fail.

As a general rule, it is time to see a dermatologist when:

• Pimple breakouts are severe, recurrent, or persistent.
• You have a pimple on the armpit, groin, or thigh (as it may turn out to be a boil).
• You get pimples before the age of 8 years.
• You started prescription medications within six months and suddenly have an acne breakout.
• You have developed (or are developing) acne scars.
• Pimples are causing you distress.
  

Prevention

You can't always avoid getting a boil or pimples, but there are simple measures you can take to reduce the risk.

Preventing Boils

To reduce the risk of a boil:

• Clean any cuts, wounds, or abrasions (even small ones) as soon as they happen.
• Wash your skin regularly with a mild antibacterial soap.
• Cover any cut or wound with a sterile bandage until it heals.
• Eat a healthy diet and exercise regularly to boost your immune system.
  

Preventing Pimples

To reduce the risk of pimples:

• Gently clean your skin up to twice daily with a non-abrasive cleanser.
• Use skincare products labeled “alcohol-free."
• Shampoo regularly, and keep oily hair off your face.
• Stay out of the sun, and avoid tanning beds.