Underarm rashes are typically caused by heat, friction or contact with allergens.

© iStockphoto.com/Robert Byron

Getting rashes under your arms can really be the pits, but while these rashes have a variety of causes, most aren't cause for alarm. An armpit is a dark, moist place that's a perfect breeding ground for bacteria and other microbes. Some of these bacteria produce odor as they grow, which is why many people use deodorant, but sometimes both the microbes and that deodorant can work against you -- the result is a rash.

An underarm rash isn't usually the result of poor hygiene -- in fact, a rash may occur as the result of a product you use to stay clean and odor-free. Perfumes, deodorants and drying soaps can all cause an allergic reaction, and even shaving under your arms can cause a rash [source: Mayo Clinic].

Rashes come in all shapes and sizes -- some appear as raised patches of blotchy dry skin, others as itchy red bumps or pimples. Some rashes hurt, others itch like crazy, and others may cause no pain or itching at all [source: Mayo Clinic]. But given how sensitive your underarm area is, even when a rash is painless, you'll want to get it cleared up as soon as possible.

If you spot a breakout, don't be rash -- step back and use the following information to figure out the cause and treat the problem. But don't hesitate to visit your doctor if the problem persists or if the rash is accompanied by other symptoms.

Keep reading to learn about the causes of underarm rashes.