An armpit rash can be an annoying and uncomfortable problem. The armpit area is prone to friction, sweating, and irritation which can all contribute to rashes developing. While rashes under the arm are rarely a serious health concern, they can still cause redness, itching, pain, and embarrassment. Understanding the various causes of armpit rashes and how to properly treat them is important for finding relief.
Understanding Armpit Rash
An armpit rash refers to any inflammatory skin condition that affects one or both armpits. The rash can appear as a general red, bumpy area or may present with more specific symptoms like small blisters, pimples, or scaly flaky skin. An armpit rash is usually differentiated based on its specific characteristics and possible causes.

The rash may be localized to just the underarm area or in some cases may spread to the upper arm, chest, back, or other nearby areas of the body. Some common types of armpit rashes include heat rash, folliculitis, eczema, and fungal infections.
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What Are The Causes Of Armpit Rash?
There are a number of possible causes and contributing factors when it comes to developing an armpit rash. Here are 6 of the most common:
🔶 Heat Rash
Also known as prickly heat, heat rash is one of the most prevalent causes of an armpit rash during hot, humid weather. It develops when the sweat ducts become blocked and swell up, forming an itchy red rash. Heat rash typically appears as scattered small red bumps or welts on the skin that cause a prickling or stinging sensation. The armpits are prime real estate for heat rash since the area is prone to sweating and friction from arm movement.
🔶 Contact Dermatitis
Contact dermatitis is a rash caused by the skin coming into contact with an irritant or allergen. The armpit area frequently comes into contact with deodorants, fragrances, soaps, laundry detergents, and fabrics that can cause irritation and contact dermatitis. The rash appears as reddish, scaly, itchy patches under one or both arms. It may also ooze or weep clear fluid. Contact dermatitis often resolves once the offending irritant is removed.
🔶 Shaving Irritation
For those who regularly shave or wax their armpits, razor burn is a common culprit of armpit rashes. Shaving can create micro-abrasions, nicks, and irritation under the arms. This can lead to painful red bumps, ingrown hairs, and pimples around hair follicles. Avoiding close shaves and being gentle is key to preventing underarm shaving rashes.
🔶 Yeast Infection
Candida yeast naturally lives on the skin but when it overgrows, it can cause skin infections. The dark, moist environment under the arms provides the ideal breeding ground for yeast overgrowth. A yeast infection rash in the armpit appears as a red, itchy rash with small pustules and white-headed pimples. Yeast thrives on high carbohydrate diets, humidity, poor hygiene, and impaired immune systems.
🔶 Bacterial Folliculitis
Bacterial folliculitis is an infection of the hair follicles caused by bacteria like Staphylococcus. It presents as small red bumps or pus-filled pimples surrounding hair follicles. The underarms are prone to this because of friction, sweat, and shaving irritations that can allow bacteria to enter follicles. Folliculitis is most common in individuals with compromised immune function. Good hygiene and not shaving while infected can help clear it up.
🔶 Eczema
Eczema is an inflammatory skin condition that can arise along with allergies and asthma. The armpits are one of the typical hot spots for eczema to flare up as a very itchy, scaly, dry rash. Eczema worsens when the skin barrier is compromised so armpits are often impacted by shaving, sweating, and deodorants. Managing triggers and using gentle cleansers and moisturizers helps control eczema outbreaks.
How To Treat Armpit Rash?
Depending on the cause of the armpit rash, there are a variety of effective treatment options available. Some general tips include:
- Avoid shaving and waxing the underarms when a rash is present. This can exacerbate irritation.
- Use a gentle, fragrance-free cleanser on the underarms. Avoid harsh soaps.
- Apply a cold compress on the rash to help soothe itching and inflammation.
- Use an over-the-counter hydrocortisone cream to reduce redness and swelling.
- For infectious causes, use an antibacterial or antifungal ointment.
- Keep the underarms clean and dry to avoid worsening the rash.
- Wear loose, breathable fabrics such as cotton to allow airflow to the skin.
- Oral antihistamines like Benadryl can help resolve rashes due to allergies or contact irritants.
For chronic, recurring, or more severe rashes, see a dermatologist who can properly diagnose and prescribe stronger topical or oral medications. They may also recommend patch testing to identify possible allergies triggering rashes. Most armpit rashes can be effectively treated at home with conservative care and avoidance of irritants. See a doctor if the rash persists, causes intense itching, or shows signs of infection like oozing pus, spreading redness, or fever.
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Conclusion
Armpit rashes are a nuisance but a very common affliction. The repeated friction and moisture under the arms create the perfect environment for many types of rashes to emerge. Heat rash, yeast infections, eczema, and contact dermatitis represent some of the most prevalent culprits. While usually not a major health issue, armpit rashes cause discomfort and irritation.
Identifying triggers and using mild cleansers, topical creams, and avoiding shaving is key to treating most armpit rashes. With proper care, the rash should resolve within one to two weeks. However, see a doctor for any severe, worsening, or recurrent rashes. Paying attention to underarm skin health helps prevent and catch armpit rashes in their early stages.
FAQ
A: Most armpit rashes like heat rash, folliculitis, and eczema are not contagious. However, some fungal or bacterial infections under the arms could potentially spread through skin-to-skin contact or sharing of personal items. Practicing good hygiene helps prevent transmission.
A: The duration of armpit rashes varies depending on the cause. Mild irritant rashes may clear within a few days while fungal infections can persist for several weeks. Most resolve within 1-2 weeks with proper care and treatment. Seek medical advice if rashes last longer.
A: See a doctor if the rash is very painful, does not improve with over-the-counter treatment, or shows signs of infection like oozing pus, spreading redness/swelling, lymph node swelling, or fever. Also, seek medical care if rashes are chronic or frequently recurring.
A: Avoiding irritation and maintaining good hygiene are key to preventing armpit rashes. Use gentle cleansers, don’t shave over rashes, wear breathable fabrics, minimize deodorants and fragrances, and keep the area clean and dry. Promptly treating any rashes also helps prevent worsening.
A: Yes, deodorants and antiperspirants, especially those with heavy fragrances, can irritate sensitive underarm skin and cause allergic rashes or contact dermatitis for some people. Switching to a gentler, fragrance-free formula often resolves these rashes.