Pimple in your armpit: causes

Armpit bumps get treated as acne, and that is usually the wrong starting point. Skinli explains why below, and what the right starting point is instead.

The armpit has dense hair, gets shaved regularly, folds against itself and stays warm and damp. Every one of those favours a hair follicle problem rather than a blocked pore. So the useful treatment is often subtraction rather than adding a product.

What it usually is

An infected hair follicle, not acne.

The American Academy of Dermatology describes folliculitis as a common skin infection that develops in the hair follicles. It gives the general rule that folliculitis can appear anywhere on the skin, except for our palms and soles. And it names the cause that matters here: shaving is a common cause of folliculitis.

It also explains the confusion directly. The infected hair follicles can look like another skin condition, such as acne. That resemblance sends people to acne products for a problem those products do not address.

The American Academy of Dermatology adds the other half of why the armpit is prone to it: when your skin is damp and hot, it is easier to damage your hair follicles and get an infection. An armpit is damp and hot by design.

An ingrown hair belongs to the same family. The hair curls back or grows sideways into the skin rather than out through the follicle, leaving a small painful bump that sometimes shows a dark line inside it.

Why shaving the armpit causes trouble

The armpit is one of the harder places on the body to shave cleanly, and the reasons are structural.

The hair grows in several directions at once, so a single stroke cannot follow the grain. The skin is loose and folds, so it moves under the blade. And the shape of the area means people shave by feel rather than by sight.

What helps:

Shave less often and let the skin recover between times. Daily shaving on already irritated skin keeps the cycle running.

Replace the blade before it drags. A blunt blade pulls at hairs rather than cutting them, which is how an ingrown hair starts.

Do not stretch the skin tight for a closer cut. That cuts the hair below the surface and invites it to grow sideways.

Do not go over the same patch repeatedly looking for perfect smoothness.

And do not apply deodorant or antiperspirant immediately onto freshly shaved skin. Give it some hours. A product applied to raw skin stings and irritates, and irritated skin reacts more to everything else.

If you wax rather than shave, the same follicle disturbance applies, and bumps appearing a day or two afterwards fit the same picture.

What not to do

Two things, and people do both.

Do not squeeze it. The American Academy of Dermatology warns that if you push some of the contents inside the pimple deeper into the skin, which often happens, you increase inflammation, and that you risk getting an infection from the bacteria on your hands. The armpit is warm, moist, folded and hard to see properly, which makes it a poor place to break the skin deliberately.

Do not dig out an ingrown hair with tweezers or a needle. That turns a small bump into a small wound in the least hygienic area available, and it can leave a mark where the follicle was.

What actually helps

Stop shaving that armpit until the bump has settled. That is the single most effective thing on this page, and it costs nothing.

Keep the area clean and dry. Wear looser clothing and breathable fabric while it heals, so the skin is not held damp against itself.

For a sore bump, the American Academy of Dermatology advises applying warm compresses to the area, and for a deep painful spot it describes soaking a clean washcloth in hot water and applying the warm, damp washcloth for 10 to 15 minutes, three times daily. Our guide on a warm compress for a pimple covers the method.

If you want to use a product, a benzoyl peroxide wash is better suited to this area than a strong leave-on cream, because the skin is thin and folded and irritates readily. Our guide on acne body wash covers the choices, and benzoyl peroxide for folliculitis is the closest fit for this problem. Two cautions: never apply it to freshly shaved skin, and remember that benzoyl peroxide bleaches clothing.

Most single bumps settle within a week once the cause is removed.

The pattern that needs a name

This is the part of the page worth reading even if your bump cleared yesterday, because people spend years on the wrong treatment for it.

The NHS describes hidradenitis suppurativa as a painful, long-term skin condition that causes skin abscesses and scarring on the skin. It says the lumps develop on the skin in the following areas: around the groin and genitals, in the armpits, on the bottom and around the anus, and below the breasts. It describes a mixture of boil-like lumps, blackheads, cysts, scarring and channels in the skin that leak pus.

The NHS then says the thing that matters most here: hidradenitis suppurativa could be mistaken for acne or ingrown hairs. And it adds that it is important to recognise and diagnose the condition in its early stages to prevent it getting worse.

Those areas are precisely where skin rubs against skin. The pattern to recognise is painful lumps that keep returning to the same places, that leak, that heal into scars, and that no body wash has ever touched.

If that describes your armpits, it is worth asking a doctor about this condition by name rather than trying another product. Our guide on a pimple on your breast covers the same condition where it affects the skin under the breast, and butt acne covers another of the areas the NHS lists.

Should you stop shaving altogether?

This question comes up once people realise shaving is the cause, and the honest answer is that it depends on what you want.

Armpit hair removal is a choice, not hygiene. If you stop, the folliculitis problem largely stops with it, because the follicle is no longer being disturbed every few days. Plenty of people take that route once they connect the two.

If you want to keep removing it, the methods rank in this order. Trimming with clippers leaves the follicle alone entirely and causes the fewest bumps of the three, while leaving short hair behind. Shaving with a sharp blade, less often, with the cautions above, sits in the middle. Waxing and plucking disturb the follicle most, because the hair is pulled out rather than cut.

There is no need to decide permanently today. Stopping for three or four weeks is a clean test on its own: if the bumps disappear during that time and then come back when you start again, you have your answer, and you can decide what to do with it from there.

What does not work is continuing exactly as before while adding a product on top. If the follicle keeps being disturbed every few days, no wash will outrun it.

When an armpit lump is not a spot at all

The armpit contains lymph nodes, which the face does not.

A lump deep under the skin that you can move with your fingers, rather than a bump on the surface, may be a swollen lymph node. Those commonly swell when you have an infection somewhere and settle again afterwards. No skincare affects them.

The NHS advises seeing a GP if you notice a lump in your breast or armpit, so an armpit lump is specifically worth having looked at rather than watched. That is a short appointment.

When to see a doctor

Go sooner rather than later if the swelling is spreading, red and hot, if you have a fever, if the lump is deep, firm or growing, if it has lasted more than a few weeks, or if painful lumps keep returning and leaving scars.

For folliculitis that will not clear, the American Academy of Dermatology says it can be helpful to see a dermatologist to make sure you have folliculitis, and that some people need medication, such as an antibiotic, to clear it. Our guide on body acne or folliculitis covers the distinction in more detail.

For the same condition under the breast, see pimples on your breast, and for shaving bumps on the neck see neck acne. Our hub on acne by face area covers the face, area by area.

For the skin on your face, the photo check counts what it can see and builds a plan from it.