What Makes Mosquito Bites Itchy and What to Do About It

Scratching mosquito bites can inflame the skin, and inflammation can make the skin more itchy. Here’s what causes itchy mosquito bites and what to do about it. (Kanachaifoto, Adobe)

Estimated reading time: 5-6 minutes

ATLANTA — If you’ve ever been bitten by a mosquito, you know how frustrating it can be to be bitten by a mosquito. The little red bump swells almost immediately, creating an itching that only seems to get worse once you start scratching. The more you scratch, the more itchy they become—starting a vicious cycle that leaves you irritable, sore, and full of red bumps.

Some seem to be mosquito magnets — insects swarm wherever they are, leaving a bite on any exposed flesh — while others are relatively unscathed and itch-free.

How do mosquitoes choose their prey and how do we repel them? We interviewed some experts for their advice.

Why do mosquito bites itch?

When a mosquito bites you, it uses special mouthparts (proboscis) to pierce the skin to suck blood. When a mosquito feeds on your blood, it injects saliva into your skin, according to the Centers for Disease Control and Prevention.

Mosquito saliva has properties similar to anesthetics, so you won’t feel the bite until the insect flies away, explains Leslie Vosshall, Howard Hughes Medical Institute vice president and chief scientific officer. It also contains anticoagulants so your blood will continue to flow without clotting.

“Mosquito saliva contains a lot of proteins; some are allergens,” Vosshall said, adding, “Our bodies recognize mosquito proteins as foreign, and our immune cells go into action to try to fight it.”


Our body recognizes the mosquito protein as foreign, and our immune cells take action to try and fight it.

—Leslie Vosshall, Howard Hughes Medical Institute


It’s not the bite that’s causing the itching — it’s actually the body’s response to the foreign mosquito protein it’s trying to fight. That’s why some people may have only a mild reaction to the bite, while others are more sensitive to foreign proteins, experience extensive swelling, and be more painful.

And there is no need to be angry with male mosquitoes because only female mosquitoes bite. They bite to eat blood meal because most female mosquitoes cannot lay eggs without blood.

How do mosquitoes choose their prey?

Like most other blood-sucking insects, mosquitoes can smell us from a distance through the carbon dioxide we exhale, and that’s what they are, says Daniel Markowski, technical advisor to the American Mosquito Control Association. The reason for approaching in the first place.

“Once they get really close to the owner, they use all sorts of other cues to eventually hone in,” he said. “These include visual elements such as shape, size, and color. That’s why dark colors are not recommended for major Skeeter habitats, as they stand out more, especially in context and contrast.”

He added that other chemical cues “including breath odors, microbiota byproducts on our skin, or other general human odors such as octenol, ammonia, caproic acid or lactic acid” combine with our carbon dioxide to make us More or less attractive to different mosquito species. .

It’s most likely a combination of a person’s carbon dioxide and other odors that attract mosquitoes, says VosshalI, who recently wrote a paper on “Mosquitoes’ Unbreakable Attraction to Humans.” But the jury is still out on what exactly makes one person more attractive to mosquitoes than another, she said.

“That’s what we’re looking at — the amount and type of body odor a person emits could be the cause,” Vosshall said via email. “There are papers claiming it’s blood type, or the sweetness in blood, or gender (women are said to be more attractive to mosquitoes), but nothing conclusive.”

What resists the urge to scratch?

“Don’t scratch” is the advice given by most experts and health professionals. As difficult and sometimes impractical as it sounds, scratching can inflame the skin, and inflammation can make it even more itchy.

“Scratching can also lead to secondary infection and prolonged stimulation,” warns Markowski, adding that in extreme cases, people can scar themselves.

Instead, there are dozens of creams and sprays for itching relief as well as home remedies and repellents, so choosing the right one for you often comes down to trial and error.

“Overall, all the various anti-itch creams are very similar,” Markowski said. “Generally, I recommend that if you’re highly allergic to mosquitoes, you may need a cream that contains benadrine or a similar antihistamine.”

Vosshall recommends using hot water on the bite as soon as possible.

“Very hot water — heat you can tolerate without burning yourself — short-circuits the itch reflex,” she says.

“If you’re hiking and that’s impractical, topical lidocaine topical anesthetic gel can help prevent itching sensations along with over-the-counter cortisone creams.”

While both experts said many prefer natural remedies or herbal products, they urged caution. There is no scientific evidence that these treatments work, and they may come with their own precautions or side effects.

In fact, the best way to fight itching is to prevent bites in the first place.

“Chemical repellents, including DEET or picaridin, are safe and effective,” Vosshall said. Markowski agreed, describing DEET as the “gold standard,” registered with the Environmental Protection Agency and recognized by the CDC.

However, he acknowledged some concerns about the ingredient’s toxicity, adding: “As with all products, I recommend treating a small area first and making sure you don’t have any allergic reactions. Also, make sure you read the label and follow all directions for use. .”

For comprehensive guidance on insect repellents, the CDC lists options for EPA registration on its website, and the EPA website provides a search tool to help you find the right option.

When to seek medical attention

Some people have severe allergic reactions to mosquitoes, although in practice this is rare, Vosshall said. Seek immediate medical attention if you experience severe symptoms such as hives, difficulty breathing, or an allergic reaction.

You should also see your doctor if you plan to travel to countries where blood-borne pathogens such as Zika and malaria are common. Mosquitoes can transmit some diseases from person to person, but if a vaccine or preventive treatment is available, your doctor will be able to advise you.

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