The skin under the arms is thin and delicate. It contains many sweat glands and hair follicles that can become clogged. As a result, the armpits are prone to pimples, boils, and other skin issues, which can be uncomfortable.

Many everyday factors can cause armpit pimples and bumps, including friction, ingrown hairs, razor burn, and bacterial infections.

Even though red bumps and pimples may all look the same, there are some distinct differences in how a doctor will diagnose and treat them.

Home remedies or medical treatments can often be effective in treating armpit pimples.

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Causes of a pimple in the armpit may include friction, razor burn, and folliculitis.

The underarm area gets exposure to quite a lot of friction as the arms swing back and forth. Whenever skin rubs over skin, it is possible that injury, irritation, and even infection can result.

The skin can also rub against tight clothing, the band on a bra, and the straps of a purse or backpack.

This friction can contribute to inflammation and irritation in the armpits, leading to clogged pores and pimples. People often sweat in the armpits, even after using a deodorant or antiperspirant, and this moisture can worsen the irritation.

Routinely using a razor to remove the hair from under the armpit increases friction and irritation to the delicate skin in this area.

Shaving the skin under the arms can sometimes cause a red, bumpy rash and skin irritation. It can be itchy and uncomfortable but tends to resolve within a few days.

Razor burn is especially likely if a person uses an old or dull razor or does not moisturize the skin. Using an old or dull razor can also introduce bacteria into small breaks in the skin, which can lead to a skin infection, such as folliculitis, or boils, which can resemble pimples.

If a person shaves the hair from their armpits, ingrown hairs may also result.

An ingrown hair is a hair that has grown out of the hair follicle and then coiled or curled around to grow back into the skin again.

In some cases, an ingrown hair curls and turns back into the hair follicle before it even exits the skin.

Ingrown hairs should resolve on their own. It is important to avoid picking at or breaking the skin over an ingrown hair as this can introduce bacteria, which may cause folliculitis.

Folliculitis is an infection of the hair follicle.

Folliculitis looks like a red bump in or near the hair strand, and it can contain pus or blood.

If bacteria are the cause, people may treat folliculitis with antibiotics. An antibacterial soap, such as a benzoyl peroxide wash, can also help kill the bacteria on the skin. However, this can be very irritating to the skin in some individuals.

It is best to speak with a dermatologist before using any over the counter antibiotics since these can sometimes cause an allergic skin reaction called allergic contact dermatitis.

People can prevent reinfection by using a new razor and keeping the armpits clean and free of bacteria. Shaving in the direction of hair growth can help prevent folliculitis.

There are other causes of folliculitis, aside from bacteria, which may require further evaluation by a dermatologist to diagnose.

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A person can talk to a dermatologist to determine what is causing their allergic contact dermatitis.

Allergic contact dermatitis occurs when the skin comes into contact with a substance or ingredient to which the skin is allergic.

In the armpit, this could be a deodorant or antiperspirant, or even a soap or detergent that the person uses to wash their clothing.

Allergic contact dermatitis causes a red, bumpy rash that is very itchy. In the initial stages, fluid filled blisters may appear.

People can work with a dermatologist to determine what is causing the reaction. Avoiding the allergen should clear the rash. Sometimes, patch testing is necessary to confirm the problematic ingredient.

Certain medications can help relieve allergic contact dermatitis. Over the counter antihistamines can help with itching, and topical steroid creams may be enough to soothe a mild reaction.

Boils, or furuncles, are red and painful bumps resulting from a bacterial infection.

Boils are more likely to appear on skin that gets exposure to moisture and friction, such as that in the armpits and groin.

Without treatment, boils can continue to grow larger and more painful. However, over time, they will usually burst open and heal on their own. A person should avoid squeezing and popping a boil as this can worsen the infection.

Applying a moist heat pack a few times a day can help speed the healing process. Once the boil ruptures, a person can apply petroleum jelly and then cover it with sterile gauze until it heals.

If a boil worsens or does not go away on its own within a few weeks, or if the person has a fever or feels unwell, they should see their doctor. In some cases, the doctor will need to make a small incision to help the boil drain and heal.

Areas of the skin that often become moist are at risk of developing a yeast or fungal infection, which an organism called Candida causes.

Yeast infections frequently produce red bumps or pustules, which are pus-filled red blisters.

People can often treat yeast infections with over the counter antifungal creams. A yeast infection can resemble other conditions that need different treatment, so it is best to get a diagnosis from a doctor.

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A doctor may suggest lifestyle changes, such as weight loss and quitting smoking, to help treat hidradenitis suppurativa.

Hidradenitis suppurativa is a skin condition that most commonly involves the armpits and groin but can affect other areas. It starts with the growth of red, pimple-like bumps on the affected skin.

Without treatment, it can worsen as the bumps expand and go deeper into the skin. It can be painful and might even make moving the arm difficult. Over time, the bumps may cause severe scarring that results in sinus tract formation and drainage.

Doctors use various methods to treat hidradenitis suppurativa. These may include:

  • medications, such as antibiotics
  • lifestyle changes, for example, weight loss and quitting smoking
  • surgical resection of the affected areas
  • antibacterial washes, such as chlorhexidine 4% wash and benzoyl peroxide 10% wash

In some cases, these treatments are not successful, and doctors will inject a biologic medication called adalimumab (Humira) instead.

Whichever treatment the doctor or dermatologist recommends, it is important to follow their instructions carefully.

Armpit pimples are a common occurrence. The armpits contain many sweat glands and hair follicles, and they often encounter friction, moisture, and a variety of topical products, all of which can cause pimples or bumps. Shaving the armpits may also cause pimples.

In some cases, it is possible to treat armpit pimples at home. People can see their doctor if they are concerned about what might be causing the pimples or if the pimples are worsening or not resolving.