Stinky underarms aren’t unusual, but when one man’s stubbornly smelly armpits lasted for four years, doctors knew something was, uh, fishy.

According to a report appearing in a recent issue of The New England Journal of Medicine, the 40-year-old’s underarm hairs were infected with bacteria known as Corynebacterium tenuis. The hair shafts were covered with—beware: what follows is pretty gross!—a creamy, yellow substance that emitted an irrepressible odor.

This man’s case is a stark reminder that our skin is crawling, usually unbeknownst to us, with hundreds of types of bacteria. And some of these stealthy germs can lead to serious illnesses such as sepsis (a potentially deadly inflammatory response throughout the body) and pneumonia.


The good news is, most skin bacteria, which outnumber our body’s own cells, are harmless and even protect skin cells from more dangerous microorganisms.

For example, harmless Staphylococcus epidermidis takes up space on our skin that the insidious Staphylococcus aureus—usually called “staph”—would otherwise colonize. Scientific research is increasingly indicating that the vast majority of skin bacteria inhibit disease-causing agents or even “educate” the immune system to help us fend off illness.

Harmful bacteria, however, tend to congregate at certain skin sites that are either moist or oily. Here are four of the most common “hot spots” for harmful bacteria—and the red flags that mean you should get to a doctor…

HOT SPOT #1: Tip of the nose. The anterior nares (the ends of the nostrils) are the most common site for colonized methicillin-resistant Staphylococcus aureus, or MRSA. Some forms of this highly dangerous bacteria can cause sepsis and even death. MRSA also can colonize in areas inside the nose.

About 2% of people carry MRSA (often harmlessly) on their skin—it also can congregate in adults in the armpits and groin area.

What to look for: Constant irritation at the tip of the nose, which may include tiny skin cracks called fissures, can clue you in to MRSA’s presence. Another tip-off is the development of numerous or recurrent boils anywhere on the body. If you develop one of these signs, see a doctor.

HOT SPOT #2: Between the toes. The webby region between the toes and the cuticle areas on toes and fingers can harbor Pseudomonas aeruginosa bacteria, which can cause an infection of the toes and feet, especially in people who sweat a lot or are active and wear closed-toe shoes. The infection may cause pain and difficulty walking and can result in cellulitis (an infection just below the skin surface) or sepsis in people with weak immunity.

What to look for: A discharge that may stain socks a green color and a sweet, grapelike odor.

HOT SPOT #3: Armpits. The Corynebacteria causing the 40-year-old man’s long-term odor have a fondness for armpits and the groin area, coating the hair shafts with a “cheesy” yellow paste. The infection, called trichomycosis axillaris, is most common in tropical or other warm climates. Similar bacteria can cause infections of the feet.

What to look for: A noticeable smell, and if the feet are infected, small, “punched out” pitting of the soles.

HOT SPOT #4: Scalp/hairy areas. While the scalp is the most reliably hair-covered spot on our bodies (or so we hope), hair follicles cover almost our entire bodies. In men, of course, the hair tends to be more visibly abundant—for example, on the chest, back and face.

Densely packed areas of hair follicles can be the target of Propionibacterium acnes, which plays a role in the development of inflammatory acne that’s typically far worse than a blackhead or two.

What to look for: Pustules and/or large, painful bumps grouped on the face, chest or back.


And what about the man with the smelly armpit infection? After the hair was shaved, he received an antibiotic for the infection and topical aluminum chloride to curb his armpit sweating, which had created the ideal home for the bacteria.

Remember: Most bacteria are ben-eficial. Still, it’s wise to inspect your skin regularly for the red flags of infection described in this article. Avoid antibacterial soaps unless directed by your doctor. These soaps disrupt the normal skin barriers that protect us from invading bacteria and other pathogens. Plain soap and water are usually the best way to wash.


A nasty collection of pus under the skin, known as a boil, is an infection typically resulting from Staphylococcus aureus, more commonly referred to as “staph.”

Recurrent boils, however, can signal infection with MRSA, a drug-resistant form of staph that can cause pneumonia or severe infections of the blood, bones, heart valves or lungs. Boils can occur anywhere on the body but are more common in the armpits, groin and the area between the genitals and anus.

Important: Seek medical attention for boils larger than one-half inch in diameter, which should be professionally drained. The same goes for boils with red streaks around them, which can be a sign of dangerous blood vessel involvement…boils that continue to enlarge…if a fever develops or lymph nodes enlarge…or if the boil is near the anus.

Also, see a doctor about any boil on the spine or face. Boils on the spine can lead to a spinal cord infection, and those in the triangular area between the eyes, cheeks and lip can trigger a dangerous brain infection.

Most other boils are small and can be treated at home.

What to do…

  • Apply a compress soaked in warm salt water three times per day for 20 minutes. Use a fresh washcloth each time.

What not to do…

  • Never squeeze or pop a boil, which can spread the infection.
  • Do not stick a needle or other object into a boil—this can cause dangerous bleeding or spread the infection.