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.

What Is a Boil?

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?

What Causes a Pimple?

young woman inspecting her skin in front of the bathroom mirror and looking upset

A pimple is caused by a blocked pore.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. 

Where Do Pimples Develop?

If the big blemish is 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. 

Where Do Boils Develop?

Got a big lump on your groin or thigh? Maybe it's on your breast, armpit, or behind. It's probably a boil.

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.

How Big Are Boils?

Is your blemish larger than a nickel? It's 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.

How Big Are Pimples?

Got a dime-sized breakout or smaller? It's 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.)

How To Treat a Big Pimple

So you've determined it's not a boil, but rather a big zit that's not going away. Left untreated, your pimple should heal within seven to 10 days, but the lump underneath the skin can take longer to go away.

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.

How To Treat a Boil

Boils can often be treated at home with a little TLC. 

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.

A Word from Verywell

Even though they can look remarkably similar, boils and big pimples are completely different skin problems. They're treated differently too, so it's important you know exactly what you're dealing with before starting with home care.

Still not sure exactly what is causing your inflamed whitehead? Give your doctor a call. He will be able to tell you with just a simple exam, and help you treat your skin problem effectively.

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