Bedbug bites, mosquito bites, spider bites and fly bites can break your skin. Bacteria (usually strep or staph) can enter the skin, especially when you scratch an itchy bug bite. The bacteria can cause cellulitis, a skin infection that causes red, swollen skin and fever. Antibiotics can help.
Cellulitis occurs when bacteria enter the skin, causing an infection. The infection may go deep into tissue and cause serious problems. Group A Streptococcus (strep) and Staphylococcus aureus (staph infection) bacteria are the most common causes of cellulitis. These bacteria enter the body through breaks in the skin.
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Yes, you can get cellulitis from a bug bite. If you pick at or scratch an itchy bug bite, you provide an opening for bacteria to enter the skin and tissues. The bacteria may come from underneath your fingernails or another source.
An insect can’t give you cellulitis. There’s nothing in an insect’s saliva or venom that causes cellulitis. The bite can irritate your skin and make it itchy. When you scratch, bacteria can enter.
It’s uncommon for cellulitis to spread from one person to another. You may get the infection if an open wound comes into contact with fluid-filled blisters or pus from a person who has cellulitis. These fluids can contain the bacteria that cause infection.
Bacteria like strep and staph cause cellulitis. Breaks in the skin (from a wound or dry, cracked skin) let bacteria into tissue underneath the skin. The bacteria grow and multiply, causing an infection.
Everyone has some amount of dirt and germs underneath their fingernails — even when fingernails look clean. When you cause an opening in the skin by scratching an itchy insect bite with your fingernails, germs on your skin or under your fingernails can enter.
Children who spend a lot of time outdoors playing may be more prone to getting cellulitis this way. But it can happen to adults, too. Even if you don’t scratch, the tiny opening from the insect bite can let germs in.
Children spend more time outside and tend to get more bug bites than adults. Their fingernails are often dirtier, too. These factors increase a child’s risk for cellulitis.
Other cellulitis risk factors include:
Any type of bug bite can lead to cellulitis. These include:
Cellulitis develops in the area where bacteria enter the skin. It can appear anywhere on the body. In adults, cellulitis often affects a leg or foot. In children, cellulitis more commonly affects the face and neck.
Signs of cellulitis include:
You can use a washable marker to draw a border around the red, swollen bug bite area to track its size. You should contact your healthcare provider immediately if redness, swelling or blisters expand outside this border. Your provider may monitor the bite infection this way to make sure the infection clears up with treatment and doesn’t get worse.
Your healthcare provider can diagnose cellulitis by looking at the skin and assessing symptoms. Blood tests can identify the bacterial cause of the infection, but these tests aren’t usually necessary.
Cellulitis treatments include:
Cellulitis can be dangerous if the infection is severe or spreads. Some people need intravenous (IV) antibiotics in the hospital. You may develop a skin abscess that requires draining.
Rarely, these complications may occur:
You can lower the risk of cellulitis from a bug bite by trimming fingernails and taking these steps:
To lower your family’s risk of insect bites:
Most people feel better after about five days of taking antibiotics. Severe cellulitis may last two weeks or longer. To completely get rid of the infection, it’s important to take all of the antibiotics, even if you start to feel better.
Sometimes, symptoms get worse for a few days after you start treatment. This worsening of symptoms may be the result of bacteria dying off.
Having cellulitis once increases your risk of getting the infection again, usually in the same area. People who have weak immune or lymphatic systems are most at risk for recurrent cellulitis.
You should call your healthcare provider if you experience:
You may want to ask your healthcare provider:
A note from Cleveland Clinic
It’s tempting to seek momentary relief by scratching annoying, itchy bug bites. But you can break open the skin and expose your body to bacteria that cause cellulitis. Children have an especially hard time not scratching insect bites. Contact your healthcare provider if you or a family member show signs of infection like fever and red streaks on the skin. Antibiotics are an effective treatment for cellulitis brought on by insect bites.
Last reviewed by a Cleveland Clinic medical professional on 05/04/2021.
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