Ranging from a simple and common underarm rash from shaving to a more severe fungal rash, underarms are highly-prone to being affected. In this ideal warm and dark environment, when not properly controlled, bacteria often thrives for an unwelcome period of time.

Problems with underarm skin irritation and rashes can vary from mild cases, through extremely cumbersome and all the way to downright scary occurrences. With a wide variety of factors affecting the underarm skin, knowing what you are looking at is the first step to dealing with the underlying problem. Some of causes can include heat, allergens, immune system disorders, various infections and different medications. Many of the instances are closely connected with body sweat and bacteria that forms in its presence. Visit Sweat and Body Odor to learn more about this process.

Paying close attention to your body and taking proper precautions is an important part of getting ahead of underarm irritation and rashes and minimizing their uninvited appearance. 

Contact Dermatitis (appears in three forms)

  1. Allergic Contact Dermatitis
    Allergic reaction to an ingredient that causes an immune system to respond and affect the skin. In this instance, a person may not be able to use a product due to its composition. Allergic contact dermatitis occurs when a certain ingredient in a product comes in contact with skin, triggering an allergic reaction.

    Common culprits may include ingredients in soaps, fragrances and other cosmetic products. If you have an allergy to a specific ingredient, you should avoid products containing it.

  2. Irritant Contact Dermatitis
    Inflammation of the skin that occurs when particular substance directly damages the outer layer of the skin or interrupts skin's pH level.

    One example that we see with natural deodorants is a skin irritation when too much baking soda is used in a product. It occurs when a person’s body pH reacts poorly due to baking soda's alkaline properties. The severity of the reaction depends upon amount of product's baking soda and person’s acid mantle (sweat + sebum) pH level which can be affected by age, gender, or race, as well as medication, diet, and other factors. The acid mantle, usually on a more acidic side, pH of 4 to 5.5, when in contact with an alkaline product, may lead to an underarm irritation. Many people confuse this type of irritation with an allergic reaction (allergic contact dermatitis). We found that some natural deodorants on the market disregard product pH, which for some users prove to be an extreme irritant. For those with impaired skin function that do not tolerate even small amounts of baking soda, it is recommended to avoid this ingredient completely. 

  3. Phototoxic Contact Dermatitis
    Presents itself after a person’s skin is exposed to light; this chemically induced reaction mimics how the body reacts when skin is sunburned.

    Heat Rash

    Otherwise known as Miliaria or prickly heat, heat rash is a skin condition marked by small, itchy red marks occurring in hot and humid conditions. This is a common disorder of the eccrine sweat glands that occurs during times of increased humidity and heat. It can develop when sweat glands get plugged by dead skin or by infection from Staphylococcus epidermidis.

    Intertrigo is an inflammation of the body folds. Because the underarm area has skin folds and generally isn’t exposed, too much sweat can build up, causing an uncomfortable irritation. The skin-to-skin friction that takes place as you move about your day and/or your genetic predisposition can activate bacterial and yeast infections.


    Following proper cleansing, regular exfoliation, control of the odor causing bacteria and finding right products for your skin type can be a first step towards your overall underarm health. 

    These statements are not intended to diagnose, treat, cure or prevent any disease. For any medical concern you should consult with an appropriately-licensed physician or other health care worker. Never disregard professional medical advice or delay in seeking it because of something you have read on this website. Full Medical Disclaimer.