Why Do Mosquito Bites Itch?

Why Do Mosquito Bites Itch?

Summer is the season of mosquitoes. And mosquito bites are truly the worst—not only are they huge and painful, they itch like nothing else. And once you start scratching, it’s hard to stop. You can blame female mosquitoes for the grief we all face come shorts season.

“It is the female mosquitoes that bite, and there is some saliva that enters the skin while the mosquito is feasting on its blood meal,” says Amy Kassouf, MD, dermatologist at the Cleveland Clinic. “This is the protein that causes the allergic reaction—and itching.”

Basically, our immune systems see the protein as an enemy invader.

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“The proteins in the saliva are foreign and cause an immune system response,” says Dawn Davis, MD, dermatologist at the Mayo Clinic in Rochester, Minnesota. “This causes irritation and the local reaction we see as the bug bite.”

Our bodies are just particularly sensitive to mosquito bites.

Other bugs bite may not have the same impact on your immune system, Dr. Kassouf explains. And, of course, stings bees and wasps are likely to produce more pain than itch.

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Why do mosquito bites itch more when you scratch them?

Scratching a mosquito bite is a double-edged sword—it feels so good, but it also makes the itch way worse.

“When you scratch, you may release more local histamine—the chemical in the skin that causes the swelling and itching—and you may also be spreading the allergen under the skin,” says Dr. Kassouf.

If you tend to scratch until you bleed, you’re putting yourself at risk for skin infections.

“Scratching a bite opens up the skin, making it more painful or itchy and potentially causing bacterial infections (pyoderma or impetigo, even cellulitis!),” says Joaquin C. Brieva, MD, dermatologist at Northwestern Medicine in Chicago.

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Why do mosquito bites itch more at night?

You’re not imagining it—mosquito bites do itch more at night.

“Most people itch more at night because our cortisol levels (our bodies’ own anti-inflammatory hormone) is higher in the morning, and also because we are less distracted as we wind down and try to fall asleep,” says Dr. Kassouf.

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Why are some people more prone to get bit by mosquitoes?

You probably have that friend that gets eaten alive every time they are outside. There are a few reasons for why that may be.

Some people may be more prone to get bug bites based on several factors:

  • your natural scent and components of sweat

  • perfume or other scents

  • the color of your clothing

  • the time of day

  • your location (because you’ll have more exposure in wooded areas and along landscaping)

And their blood type could be to blame. One study found that mosquitoes that were released in a controlled setting landed on people with Type O blood nearly twice as often as those with Type A, and people with Type B blood were landed on somewhere in the middle.

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Why are some people bothered more by mosquito bites than others?

If you’ve ever wondered why do some mosquito bites itch more than others, it totally depends on your body.

“Everyone responds differently to mosquito bites,” says Edidiong Kaminska, MD, dermatologist at Northwestern Medicine in Chicago. While some people may have a minimal reaction, others may experience blisters and extreme swelling. But the most common reaction is simply red, itchy, swollen bumps.

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It just depends on your body’s immune system.

“Reactivity is based on the sensitivity of one’s immune system to the bite,” Dr. Davis explains.

But some people are prone to develop the big whoppers.

“People with so called atopic traits—eczema, asthma, allergic rhinitis—tend to develop more severe local reactions after the mosquito bites,” says Dr. Brieva.

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