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Mosquito bites: Why they itch — and how to get rid of them

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Don’t let mosquitoes squash your warm-weather fun. Here’s how to keep the buggers at bay.
Written by Jessica Migala
Updated on April 8, 2022

Mosquito season is ramping up. And you know what that means: itch season, too. All the pesky bloodsuckers might look the same to you. But throughout the U.S., there are more than 200 types of mosquitoes. About a dozen of them can spread illnesses such as West Nile, Zika and chikungunya, according to the U.S. Centers for Disease Control and Prevention.

So doing what you can to avoid their bites doesn’t just keep you from an annoying itch. It’s also an important step in staying healthy as the weather warms.

Here, we walk you through why mosquito bites itch, expert treatment tips and ways to avoid these run-ins.

(Before you get the skinny on skeeters, download our mobile app. It’s free — and could save you up to 80% on your prescription medication.)

How mosquitoes bite (and why they itch so darn much)

Are you a mosquito magnet? It might not be for the reasons you think. Mosquitoes detect and are attracted to you by the carbon dioxide (CO2) you emit, says Jonathan Larson, PhD. He’s an assistant professor in the department of entomology at the University of Kentucky in Lexington.

Once they’re on to you, they locate your skin by your body odor. And then they bite.

“Mosquitoes have a piercing-sucking mouthpart. It’s a needle with teeth at the tip,” explains Larson. As they jab into your skin, they introduce their saliva to your system.

Often, you’re totally unaware that any of this is happening. While that mouthpart sounds terrifying, it’s tiny. And they’ve got these tiny feet with a light touch. Plus, their saliva contains chemicals that numb the area so that you don’t feel much, if anything, Larson says.

Meanwhile, other chemicals in the saliva relax blood vessels and make blood flow easier. Once she (yep, only female mosquitos bite) fills up with blood, she’ll detach and be on her merry way.

Now here’s where the “Ugh, I was just bit” part comes in. The saliva starts an immune response. Your body releases the allergy chemical histamine. This heads to the bite to widen blood vessels so that immune cells can flood the area. In the process, histamine also causes inflammation and itching.

“Some people have a stronger reaction to a mosquito bite than others,” says Larson. Your friend may just get a tiny bump, while you get a very large, swollen area. If you get away with just a little redness, consider yourself lucky.

How to treat a mosquito bite

Reducing the itch is a goal. But you’ll also want to take steps to calm inflammation and protect the skin barrier, says Joshua Zeichner, MD. He’s the director of cosmetic and clinical research in the dermatology department at Mount Sinai Hospital in New York City.

Soothe itching by applying an ice pack to the bite. “The ice will constrict blood vessels, reduce inflammation, decrease redness and provide some degree of relief from discomfort,” Dr. Zeichner says. Need more relief? Curb swelling and itching with a 1% hydrocortisone cream. You can apply it to the bite 2 times per day for up to 2 weeks, suggests Dr. Zeichner.

You can also take an over-the-counter (OTC) oral antihistamine. This is according to the American Academy of Dermatology (AAD). Examples include loratadine (Claritin®) and cetirizine. You can find great deals on these and other OTC allergy medications at the Optum Store.

It benefits you to stop the itch, not only because scratching is distracting and annoying, but also because dragging fingernails across your skin damages its barrier. This increases the risk of infection, says Dr. Zeichner. If your skin is open, he recommends using an OTC topical antibiotic ointment such as bacitracin.

If you notice any of these symptoms, see a doctor:

  • Fever
  • Headache
  • Body aches
  • Signs of infection
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How to keep mosquitoes off you — and out of your yard

A ton of products claim to repel mosquitoes. Unfortunately, there’s not much evidence that the hands-off easy stuff, such as clip-on sonic mosquito devices, actually works, says Larson.

A study in the Journal of Insect Science concluded that of 5 wearable devices, only 1 reduced the number of mosquitoes attracted to someone. (It was the OFF!® Clip-On™ Mosquito Repellent made with metofluthrin.) Citronella candles and mosquito repellent bracelets were completely ineffective.

Bottom line: You probably need to wear repellent. According to the CDC, these mosquito repellent ingredients work (and are safe when used as directed, even if you’re pregnant or breastfeeding):

  • DEET
  • Picaridin
  • IR3535
  • Oil of lemon eucalyptus
  • Para-menthane-diol
  • 2-undecanone

Of course, if you’re out during the day, you’ll want to apply sunscreen, too. The AAD recommends against using a combination sunscreen-repellent product, as this may result in overapplying repellent. Smooth on SPF first, let it dry and then add repellent on top, the AAD advises. (Here are our favorite sunscreens.)

It’s easy to feel helpless when it comes to mosquitoes. But in addition to using a repellent, you can follow a few lifestyle habits that help keep them at bay, says Larson:

  • Decrease your alcohol intake outside. Drinking booze prompts you to produce more CO2, which attracts the buggers.
  • Wear lightweight, long-sleeved, light-colored clothing. Mosquitoes can also sense your body heat. Light-colored clothing reflects heat, hiding you from their “sight” a bit better.
  • Remove standing sources of water in your yard. All mosquitoes love still water, according to the CDC. (It’s where some lay their eggs.) If you have a birdbath, but sure to refresh it every 7 days.

And if the mosquitoes get really bad? Maybe it’s just time to head in. Before you go, grab your free prescription discount card. Simply show it to your pharmacist each time you fill a script to make sure you’re getting the best price on your medication.

Additional sources
Facts about mosquitoes and their diseases:
Centers for Disease Control and Prevention
Oral OTC antihistamines for mosquito bite symptoms: American Academy of Dermatology
Study on how well mosquito repellent devices work: Journal of Insect Science (2017). “Efficacy of some wearable devices compared with spray-on insect repellents for the Yellow Fever Mosquito”
Where mosquitoes live: Centers for Disease Control and Prevention