Hair typically grows straight up and out from the skin. Occasionally, though, a strand of hair curves and grows back into the hair follicle rather than breaking through the skin. This creates an ingrown hair.

Ingrown hairs tend to develop after shaving or tweezing. That means areas like the armpits are more susceptible to these uncomfortable bumps.

While ingrown hairs are a common cause of an armpit lump, they’re not the only possible explanation. Here’s what to know about a lump in your armpit.

What Causes Bumps in the Armpit?

Ingrown hairs can show up anywhere on the body, but they’re more likely to happen in places where you remove hair. Shaving, waxing, and tweezing remove hair strands but leave the hair follicle in place. As hair regrows, it may turn inward and not grow out of the skin.

This process can lead to an inflamed bump that’s raised, discolored, and irritated. People with coarse, thick, or curly hair may be more prone to ingrown hairs.

The underarm area can also develop bumps for reasons unrelated to ingrown hairs. Some other possible causes include:

Clogged Pores vs. Ingrown Hair in the Armpit

Clogged armpit pores and ingrown hairs can look similar, but they don’t always have the same cause. An ingrown hair happens when a hair grows back into the skin rather than out of it.

A clogged or inflamed follicle can also occur with folliculitis. Folliculitis is inflammation in hair follicles, which is often caused by infection. It can also happen after follicle damage from shaving or rubbing the area, wearing tight clothing, or soaking in hot tubs.

A single small bump after shaving may be an ingrown hair. A deeper lump, a lump that drains pus, several recurring lumps, or a lump that scars may point to something else. In those cases, the cause may be a cyst, abscess, folliculitis, or HS.

Is It an Ingrown Hair or Something Else?

If ingrown hairs keep coming back, are very painful, or drain pus, you may want to ask your doctor about HS. The condition can look like pimples, acne cysts, boils, or sores, and it’s easy to mistake for ingrown hairs or acne.

Without treatment, HS can lead to abscesses, scarring, and tunnels under the skin. Unfortunately, many people with HS are misdiagnosed with another skin condition, including ingrown hairs.

One myHSteam member shared: “I battled with HS for several years before realizing what it was. I just thought I was getting a lot of ingrown hairs. I even resorted to laser hair removal. But when the bumps kept coming back, I saw my doctor, who referred me to a dermatologist, where I was ultimately diagnosed.”

“I battled with HS for several years before realizing what it was. I just thought I was getting a lot of ingrown hairs.”

— A myHSteam member

If you think you’ve been misdiagnosed, ask for a second opinion or make an appointment with a dermatologist.