Causes Of An Itchy Underarm Rash

An itchy underarm rash is a common problem with a variety of potential causes. If severe, it can be socially embarrassing especially when the urge to itch strikes in a public place. What causes this unfortunate problem and what can be done about it?

Possible Causes Of An Itchy Underarm Rash

Antiperspirant And Deodorant

An itchy underarm rash is commonly a reaction to a product that’s applied to the underarms – usually antiperspirants.

Antiperspirants contain a variety of chemicals that can cause an allergic reaction in some people; and the underarm area is particularly vulnerable to allergic outbreaks since the skin is thinner in this region.

Sometimes fragrances found in antiperspirants and deodorants can be the trigger that brings on the redness and itching.

When choosing an antiperspirant or deodorant, look for one that has no fragrance, is hypoallergenic, and has as few ingredients as possible. If an itchy underarm rash develops from one product, try switching to another brand and see if the problem resolves.

In the meantime, apply a hydrocortisone cream from the drugstore to the irritated areas. Avoid using hydrocortisone cream for more than five days. If the symptoms haven’t improved in a week, it may not be an allergic reaction.

When treating an itchy underarm rash, stay away from soaps and skin creams that have fragrance or other harsh chemicals. Look for products that have natural ingredients such as essential oils.

Some possible causes of an itchy underarm rash

Fungal Infection

Another cause of an itchy underarm rash is a fungal infection. Fungi grow and thrive in the moist, dark environment of the underarms.

A fungal infection can cause redness, itching, and flaking similar to an allergic reaction and the two conditions can be hard to distinguish. A fungal infection is more likely to occur during the warm summer months and after a person has been on antibiotics.

Treating the area with Selsun Blue shampoo can often wipe out the fungus and clear up the rash. If this doesn’t work, see your doctor for an antifungal medication.


Red, itchy underarm rashes can also be caused by inflammation in the hair follicles, a condition known as folliculitis. Close inspection of the underarm area may reveal small bumps that are itchy or slightly painful to the touch.

Folliculitis can result from shaving the underarms without adequate lubrication or shaving with a dull razor. This causes the skin to become irritated and more susceptible to bacteria growth.

Sometimes the rash will resolve on its own when the irritation stops, but unresponsive cases can be treated with an over-the-counter antibiotic cream. In more severe cases, an oral antibiotic may be needed.

Keep in mind that follicultis is more common in people who have diabetes or an immune problem. If it’s a recurrent problem, see your doctor to rule out an underlying medical problem.

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