What’s cellulitis? A dermatologist explains | Health & Fitness

Table of Contents
The reddish pink rash spreads quickly. jlcampbell104/Flickr
Your skin usually deflects any bacteria it encounters, protecting you from all sorts of infections. However, when you get a bug bite or a rash, some of that bacteria can sneak in, potentially causing serious consequences.
For example, you might develop cellulitis – it’s the most common infection that occurs when bacteria breach the skin barrier. An estimated 1 in 503 people, or 0.2%, of the population get this painful red rash each year. It may happen after a bite or cut or if your skin gets so dry that it cracks and bleeds.
People are also reading…
When the infection happens, the area becomes painful, swollen, firm and warm. These symptoms can develop quickly, sometimes in less than 24 hours. It usually affects the feet or legs, but it can affect any part of the body – even your face. You might see red streaks or blisters in the afflicted area, and the skin can become dimply and, above all, very tender.
Most people who get cellulitis are middle-aged or older adults, but kids and younger adults can get it too. Aside from age and bad luck, risk factors include being overweight or having an immune system weakened from diabetes, cancer or HIV/AIDS. Circulation problems, such as long-standing leg swelling, also make people susceptible.
Scanning electron micrograph of Staphylococcus aureus bacteria (gold) outside a white blood cell (blue) BSIP/Universal Images Group via Getty Images
A variety of different bacteria can cause cellulitis. One of the most common culprits is Staphylococcus aureus – often called “staph.” Another common one is the same bacteria that is responsible for strep throat: Group A Streptococcus pyogenes.
Cellulitis is an infection of the deeper layers of the skin, and you can’t catch it from someone else.
If you get it, your physician will prescribe antibiotics and the condition should improve within one or two days. However, the redness may take up to four weeks to fully go away. Do not be alarmed if your skin turns slightly scaly, flaky or wrinkly as the inflammation heals.
Seek emergency care if the affected area doesn’t seem to be clearing up within three days, you run a fever of over 100.4 degrees Fahrenheit, you develop other flu-like symptoms, the redness and pain rapidly worsen or an abscess forms.
To prevent cellulitis, protect your skin by wearing appropriate clothing. You should also wash skin immediately after an injury with soap and water. If you tend to have dry skin, use moisturizers to prevent any cracking.
Why cellulitis matters
Cellulitis can become very serious.
Left untreated, it can spread to your lymph nodes or blood, causing a life-threatening condition called sepsis. Sepsis can affect and even shut down the internal organs, which can be fatal. The bacteria can also spread to the bones or the heart once they enter the blood, with possibly long-term consequences.
Doctors and other medical practitioners can diagnose cellulitis by examining your skin. In some cases, doctors may culture or sample the bacteria from the skin or blood to find the culprit. Occasionally, there can be concern that it will form deeper pockets of infection. In those cases a doctor may order a CT scan or ultrasound test.
Is it cellulitis or something else?
Just as there’s a danger of not catching cellulitis before it causes more serious problems, there is also a risk that other diseases will be mistaken for cellulitis. This confusion is something we frequently see as dermatologists.
Stasis dermatitis, which is caused by swelling of the legs from leaky vein valves, is the most common condition that looks like cellulitis. Fortunately, the two can typically be distinguished, as stasis dermatitis tends to affect both legs. Cellulitis almost always only affects one leg or arm at a time.
A hematoma, a collection of clotted blood under the skin or other areas, can also occasionally mimic cellulitis. So can gout, a form of arthritis. Like cellulitis, it can be red and painful. However, gout most commonly occurs over a joint.
Marjorie Montanez-Wiscovich is affiliated with the University of Florida. She serves as principal investigator in clinical trials with Kiniksa Pharmaceuticals and DermTech.
Arthur Mark Samia does not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.
How to stay cool without air conditioning
Tips for staying safe in the heat this summer
Staying cool without AC

Heat can foster fun summer activities, but the body shouldn’t be too hot for too long, as too much heat can harm your brain and other organs, according to the US National Institutes of Health. Sweating is the body’s natural cooling system, but when that’s not enough, there’s increased risk for developing the heat-related illness hyperthermia — signs of which include heat cramps, heat edema and heat stroke.
Staying cool can be done by using some basic supplies and knowing how to manipulate your home to control its temperatures.
Here are 14 methods for doing so.
Stay hydrated

When you’re hot and flushed, hydrating yourself is the first and foremost step to cooling down, said Wendell Porter, a senior lecturer emeritus in agricultural and biological engineering at the University of Florida.
The temperature of the water doesn’t matter since your body will heat it, he added. If your body is suffering from the heat and needs to cool itself, it can’t do that without enough moisture, since the body cools itself by sweating.
Take a cold shower or bath

Taking a cold shower or bath helps cool your body by lowering your core temperature, Porter said.
For an extra cool blast, try peppermint soap. The menthol in peppermint oil activates brain receptors that tell your body something you’re eating or feeling is cold.
Use cold washrags on your neck or wrists

Place a cold washrag or ice bags (packs) on your wrists or drape it around your neck to cool your body. These pulse points are areas where blood vessels are close to the skin, so you’ll cool down more quickly.
Use box fans

Place box fans facing out of the windows of rooms you’re spending time in to blow out hot air and replace it with cold air inside.
If the weather in your area tends to fall between 50 and 70 degrees Fahrenheit in the mornings and evenings, opening the windows on both sides of the house during those times can facilitate a cross-flow ventilation system. If you do this, you can opt to use or not use the fans, but the fans would help cool the house faster, Porter said. The outdoors can pull the hot air from your home, leaving a cooler temperature or bringing in the breeze. Just be sure to close windows as the sun comes out, then open them when the weather is cool again.
You might not typically leave windows open for safety reasons, but if you’re at home more anyway due to the pandemic, this method could be feasible, Porter said.
Just resting near a fan would reduce your body temperature as well.
Photo by Sameerah Munshi on Unsplash
Close your curtains or blinds

If you have windows that face the sun’s direction in the morning through afternoon, close the curtains or blinds over them to “keep the sun from coming directly into the house and heating up (the) inside,” Porter said.
You could also install blackout curtains to insulate the room and reduce temperature increases that would happen during the day.
If you do turn the air conditioning on, don’t set it below 70 degrees Fahrenheit in an effort to cool the house faster, said Samantha Hall, managing director of Spaces Alive, an Australia-based design research company helping to create healthy, sustainable buildings.
“It just runs for longer to reach that temp and will keep going until you start to feel a bit chilly and is then hard to balance,” she added. Instead, keep the unit temperature as high as possible while still comfortable.
Sleep in breathable linens

Cotton is one of the most breathable materials, so cotton sheets or blankets could help keep you cool through the night.
The lower the thread count of the cotton, the more breathable it is, Porter said. That’s because higher thread counts have more weaving per square inch.
Sleep in the basement

If you can’t sleep through the night because you’re too hot, try sleeping somewhere besides your bedroom, if that’s an option. Heat rises, so if you have a lower or basement level in your home, set up a temporary sleeping area there to experience cooler temperatures at night.
Photo by Point3D Commercial Imaging Ltd. on Unsplash
Don’t refrigerate or freeze blankets or clothing

Common advice for staying cool without air conditioning includes refrigerating or freezing wet socks, blankets or clothing then ringing them out to wear while you sleep. But this isn’t a good idea, Porter said.
Because of “the amount of energy they can absorb from your body that night, they will be warm in just a matter of minutes,” he said. “And then you’d have damp stuff that would mold your mattress. So you definitely don’t want to do that.”
Close the doors of unused rooms

If no one’s using a room that doesn’t have vents or registers, close the door to that area to keep the cool air confined to only occupied areas of the house.
Use the exhaust fan in your kitchen and/or bathroom

Flip the switch for the exhaust fan in your kitchen to pull hot air that rises after you cook or in your bathroom to draw out steam after you shower.
Photo by Ralph (Ravi) Kayden on Unsplash
Install energy-efficient light bulbs

Incandescent light bulbs generate a higher temperature than LED light bulbs do. To make the switch, watch for sales on energy-efficient bulbs, then slowly replace the bulbs in your house, Porter said.
Switching light bulbs can save money but won’t reduce a lot of heat in the home, Hall said. However, if you focus on switching the bulbs in areas you’re sitting near, that would make a more noticeable difference, Porter said.
Cook in the morning, with a slow cooker or outside

Oven heat can spread throughout your house. Keep the heat centralized in one area, such as a slow cooker. Or, cook outdoors on a grill to keep the heat outside.
Enjoy frozen treats

Eating an ice pop or ice cream to cool down may help for a moment. But don’t go overboard on the sugar if you’re overheated or at risk of being overheated, Porter said.
“Sugar would run your metabolism up and you’d start feeling internally hot,” he said. “So the cool treat might be good, but the extra sugar might not.”
Research what your state offers

If you’ve tried everything and still can’t beat the heat at home, you could look online for any local programs that are offering ductless air conditioners.
Depending on your state, some cooling centers — air-conditioned public facilities where people might go for relief during extremely hot weather — may be open and taking precautions to ensure they’re as safe as possible. You could start by checking with your local utility offices, as they would know who is offering certain programs, Porter recommended.