What's the Difference Between a Pimple and a Boil?

Is That Big Pimple Really a Boil?

That gargantuan whitehead on your skin may not be a monster pimple.  You may have a boil.

Really big pimples and boils can look eerily similar, especially to the untrained eye.  They both appear as swollen, painful lumps with white heads.  And when you squeeze them (not saying you should) a bunch of pus-filled gunk pours out. 

But pimples and boils are different in their causes and their treatment.  Before you can treat them appropriately, you must know what you're dealing with.  Of course, you should always contact your physician if you have any questions.

A boil is caused by an infected hair follicle.

A boil looks like a large pimple.
Image: Science Picture Co / Getty Images

Boils, also called furuncles or abcesses, are infected hair follicles.  Most often it's the bacteria staphylococcus aureus that causes those painful swellings, but other bacteria and fungus can cause boils too.

A boil looks like a pimple on steroids.  It starts out as a firm, red, painful limp under the skin's surface.  Over the course of several days, it grows larger, softens, and develops a white, pus-filled head. 

In the beginning, it can be difficult to distinguish it from a pimple because those can also start out as a firm, red, painful lump.  So, how else can we tell them apart?

A pimple is caused by a blocked pore.

Inflamed pimple
Image: Daniya Meinikova / Getty Images

A pimple is not caused by an infection.  Rather, the pore becomes blocked by a plug of oil and dead skin cells.   

This glut of oil and dead skin cells, along with the acne-causing bacteria propionibacteria acnes, irritate the pore causing redness and inflammation. 

On your face? It's probably a zit.

Zits are common on the face, upper back, shoulder and chest area.  A bump here could definitely be a zit.

Do you have persistent acne?  Severe or cystic acne can cause very large, inflamed, tender blemishes.  These cyst-like blemishes infect deeper structures of the skin than typical pimples.  These zits can look very boil-like.

But even if you don't have regular acne breakouts, sometimes you just get one monster zit.  It usually goes away within a week or so. 

In a weird place? It's probably a boil.

Got a big lump on your groin or thigh?  Maybe it's on your breast, armpit, or behind.  You won't get acne in these places, so if you have a bump there it's highly unlikely it's a zit.  Boils, however, are very common in these areas.

But boils are also common in the face and neck area, just like acne.  So location alone isn't enough to determine if it is a boil or pimple.

Larger than a nickel? Probably a boil.

One of the key signs that you're dealing with boil rather than a monster zit is its size.  Boils may start out small, about the size of a pencil eraser, but can quickly grow to the size of a ping pong ball. 

Actually, boils can get much larger than that, but by that time you've probably realized what you have is not a simple zit.

So, if your pimple is scary huge, it's most likely a boil.

Dime-sized or smaller? Probably a pimple.

OK, some pimples can get really, really big.  But even the most monstrous pimple won't get much larger than a dime.  

For example, most of those "giant pimple-popping" videos on YouTube are not pimples at all, but boils.  (And seriously, anything that big should never be popped by a layperson.  Leave that for the medical professionals.)

Treating a big pimple.

So you've determined it's not a boil, but rather a big zit.  Left untreated, your pimple should heal up within seven to 10 days. 

Ice can help relieve some of the swelling and pain from that big blemish.  You can also dab on some benzoyl peroxide nightly. 

If pimples are a constant problem, though, you'll want to get on a regular acne treatment.

I Have a Big Zit that Won't Go Away!

The Most Effective Acne Treatments

Treating a boil.

Boils can often be treated at home with a little TLC.  Our About.com First Aid Expert has all the info you need to safely treat your boil at home: Boil Treatment.

Some boils will need to be treated by your health care provider, so if you aren't getting results with good home care, your boil is getting worse, or you're generally feeling unwell, give them a call.  Your doctor can lance and drain your boil, and give you medication to help wipe out the infection.

Still not sure exactly what it is?  Give your doctor a call.  He or she will be able to tell you with just a simple exam. 

Skin Boils: Causes, Symptoms and Pictures


Moskowitz, Richard J. "Boils." Medline Plus. National Institutes of Health, 2 Dec. 2014. Web. 20 Oct. 2015.

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