It’s that time of year when a lot of us are spending more time outside, and we find ourselves a lot more exposed to pesky, itchy mosquito bites. For most of us — if we can resist the urge to claw at the bites — the dots fade, the itching goes away on its own, and the bites are little more than an annoyance. But some people get more severe allergic reactions that can be far more miserable and linger for days; these allergic reactions are sometimes referred to as “skeeter syndrome.”
Skeeter syndrome is a relatively rare inflammatory reaction to mosquito bites, according to the American Academy of Allergy, Asthma, and Immunology. Symptoms may develop hours after a mosquito bite and can include a large area of swelling, heat, redness, itching, and pain that mimics what would happen with an infection.
Here’s how to tell if skeeter syndrome is happening to you, and what to do about it:
Normal Mosquito Bites These can trigger immediate swelling and redness that peaks after about 20 minutes, followed by small itchy bumps that are usually less than 2 centimeters (about ¾ inch) in diameter, says Catherine Newman, MD, a dermatologist at the Mayo Clinic in Rochester, Minnesota.
Skeeter Syndrome The mark is bigger and longer lasting. Welts can swell from 2 to 10 centimeters in diameter (up to about 4 inches) within an hour of the bite and progress over the next several days, Dr. Newman says. Bumps can be itchy, red, painful, and warm to the touch.
“Skeeter syndrome is the result of an allergic reaction to proteins in mosquito saliva,” Newman says. “There is no simple blood test to detect mosquito antibodies in blood, so mosquito allergy is diagnosed by determining whether the large red areas or swelling and itching occur after you’re bitten by mosquitoes.”
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Who Gets Skeeter Syndrome?
People who are particularly prone to skeeter syndrome include infants and young children who have been bitten and sensitized to mosquito saliva but haven’t yet developed natural immunity, as well as people who are newcomers to a region where there are mosquitoes they haven’t previously encountered.
For kids in particular, natural immunity can take years to develop because it depends on how often they’re exposed to mosquitoes, according to a case study of toddlers and preschoolers with skeeter syndrome published in The Journal of Allergy and Clinical Immunology. Parents often try to keep kids with severe reactions away from mosquitoes, which stretches out the time it takes for children to build immunity.
People with immunodeficiency disorders are also at a higher risk, Newman says.
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How Do I Know if It’s Skeeter Syndrome vs. an Infection?
Skeeter syndrome, or an allergic reaction to a mosquito bite, is characterized by large red welts. With or without skeeter syndrome, scratching a mosquito bite until it bleeds can lead to bacterial infections.
Skeeter syndrome is commonly mistaken for a type of skin infection known as cellulitis, says Kara Wada, MD, an allergist and immunologist at the Ohio State University Wexner Medical Center in Columbus.
Cellulitis can develop when bacteria on your body gets through the punctured skin where the bite has been scratched raw, according to the Cleveland Clinic. Warning signs of cellulitis include redness spreading around the bite, pus or drainage from the wound, skin that feels warm to the touch, and chills or fever. Testing blood and skin samples can help confirm a cellulitis infection and pin down the type of bacteria present.
While antibiotics can be used to treat cellulitis, they won’t help skeeter syndrome, Dr. Wada says.
“Skeeter syndrome is typically diagnosed through taking a careful history and physical examination,” Wada adds. “In reported cases, patients typically were diagnosed after severe episodes.”
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So What Can I Do About Skeeter Syndrome? How Is It Treated?
Long-acting oral antihistamines like Zyrtec (cetirizine), Xyzal (levocetirizine), or Allegra (fexofenadine) can help ease severe allergic reactions to mosquito bites, says Purvi Parikh, MD, a specialist in infectious disease, allergy, and immunology at NYU Langone Health in New York City.
Putting ice and topical steroids on the affected area can also help, Dr. Parikh says. Sometimes symptoms are so severe that patients need a prescription for prednisone or other oral steroids.
“You should see your doctor if you’re not improving with over-the-counter treatments or you’re getting worse,” Parikh advises.
How Can I Protect Myself From Mosquito Bites to Prevent Skeeter Syndrome?
Mosquito repellent and clothing that covers exposed skin are the best prevention when it comes to skeeter syndrome (and any mosquito bites in the first place), Parikh says. Staying indoors when mosquitoes are most active and keeping windows closed can also help avoid bites. Mosquitoes tend to come out in droves at dawn, at dusk, and around wetlands.
This advice for avoiding mosquito bites is the same for people who are more prone to skeeter syndrome — they just need to be hypervigilant about these precautions.
“Individuals who are allergic who already suffer from eczema, asthma, or allergies are at higher risk,” Parikh says. “They do not necessarily need a more potent repellent, but it’s important to remember to use it and reapply frequently.”
When mosquito exposure is unavoidable, some people prone to skeeter syndrome may want to take an antihistamine prior to going outside, Newman says.
Which Insect Repellants Protect Against Mosquito Bites and Skeeter Syndrome
The Centers for Disease Control and Prevention (CDC) recommends looking for repellants with the following ingredients to help reduce mosquito bites:
- DEET Chemical name: N,N-diethyl-m-toluamide or N,N-diethyl-3-methyl-benzamide; it is found in products including Off, Cutter, Sawyer, and Ultrathon.
- Picaridin Chemical name: 2-(2-hydroxyethyl)-1-piperidinecarboxylic acid 1-methylpropyl ester; it is found in products including Cutter Advanced, Skin So Soft Bug Guard Plus, and Autan.
- Oil of Lemon Eucalyptus (OLE or PMD) Chemical name: para-menthane-3,8-diol; the synthesized version of OLE is found in products including Repel and Off Botanicals. Note that the CDC recommends looking for OLE as an ingredient in a repellant; oil of lemon eucalyptus essential oil by itself is not recommended as an insect repellant.
- IR3535 Chemical name: 3-[N-butyl-N-acetyl]-aminopropionic acid, ethyl ester; it is found in products including Skin So Soft Bug Guard Plus Expedition and SkinSmart.
- 2-Undecanone Chemical name: methyl nonyl ketone); it is found in BioUD.
“DEET remains the gold standard by which all other repellents are judged,” says Joseph Conlon, a technical adviser at the American Mosquito Control Association in Sacramento, California. “Over 25 years of empirical testing of more than 20,000 other compounds has not resulted in another marketed chemical product with the duration of protection and broad-spectrum effectiveness of DEET.”
Some studies over the years have linked DEET to some rare but serious side effects, including adverse neurological effects such as seizures, uncoordinated movements, agitation, aggressive behavior, low blood pressure, and skin irritation, according to the CDC.
“Picaridin and oil of lemon eucalyptus are remarkably close in effectiveness to DEET, without many of DEET’s putative undesirable characteristics,” Conlon says.
Whatever repellent you choose, the trick to outwitting mosquitoes is to apply — and reapply — as directed.
“Most apparent repellency failures with DEET are due to misapplications, so care should be taken to apply it thoroughly, though avoiding the eyes and mucous membranes of the nose, and to reapply when necessary,” Conlon says. Reapplying is crucial to maintain the DEET vapor barrier above the skin that keeps mosquitoes from biting.