Why do Mosquito Bites Itch? We Explain Why

It’s incredible how mosquitoes with their tiny size can cause such itchy bites. Why do mosquito bites itch and why they shouldn’t be underestimated.

They’re “blood-thirsty killers.” Mosquitoes kill close to a million people around the world each year, and cause millions to get sick.

So why do mosquitoes attack us? And why do their bites itch so much? Is it okay to itch them? Can you get sick from the bites? And what can you do about it? These five key questions will all be addressed in this blog post, so read further to learn more!

Why do mosquitoes attack humans in the first place?

You may be thinking, “mosquitoes shouldn’t even exist in the first place, all they do is come after my blood.”


One Word Describes Why Mosquitos Attack Us


That’s right, mother nature won’t always respect your boundaries. Mosquitoes need to pass on their genes to their offspring. The only way to do that is for them to feast off of a nutrient-dense blood meal. Mosquitoes will usually go after other animals, but we end up getting caught in the crossfire. Why are we so appetizing to mosquitoes then? A few key points:

Humans exhale a lot of CO2, which mosquitoes can “sniff out” from over a hundred feet away! They’ve got advanced molecular machinery in their antennae that can pick up on the CO2 you breath out. Well, let’s just try and outrun them then.

• Not so fast! If you start sweating and generate heat from any type of exercise, you’re just going to attract more of them. Mosquitoes love human sweat and heat.

• Okay, then maybe a shower could help with that. The bacteria found on your skin can influence mosquito activity, depending on the kinds of bacteria you have. Aim to maintain a healthy, diverse skin microbiome if you want to reduce the chances of getting bit.

• Your genetics and blood type may also play a role, although this is still an active area of research. Don’t blame your poor genetics just yet!

• Finally, mosquitoes are even judging what you’re wearing. Crazy right? Mosquitoes tend to go after people with darker colored clothing versus lighter ones. The reason? Dark clothing retains more heat than lighter clothing, as well as being visually more attractive to mosquitoes. Lighter clothing may be harder for them to see, but won’t prevent them from biting.


All right, don’t start hating on mosquitoes just yet. Thankfully not all of them bite humans, where the vast majority of them are actually pollinators! And it’s only the female mosquitoes that bite in order to get blood for incubating her eggs. The males are all vegetarian, going only after sugar in plant nectar. Mosquitoes themselves are also a major food source for thousands of other animals on earth.  Their place in the food chain is necessary to keep ecosystems in balance.

Of the 3000+ species of mosquitoes, only a small group are the ones that actually attack people to obtain blood.

Why Do Mosquito Bites Itch So Much?




The main reason why mosquito bites itch so much has to due with our immune system response. What exactly happens when a mosquito bites you?

A mosquito’s mouth is a long, sharp tube called a proboscis. This tube is made up of various sharp needles.  The mosquito uses these to pierce your skin, look for a blood vessel to suck out blood, and inject saliva. The saliva acts as an anticoagulant so that blood flow isn’t interrupted and a mosquito’s proboscis doesn’t get stuck. The saliva also functions as an anesthetic so you don’t feel any pain from the bite.

When a mosquito bites it injects its saliva within the dermal layer of your skin. It’s also injecting protein molecules that are considered “foreign” to your immune system. In an effort to protect you, your immune system mounts an attack against these proteins.

Special cells in your body make antibodies that then coordinate with other cells to release histamine. An overabundance of histamine is what leads to inflammation, causing the itching and red bump that you see.

The itching is a sign that your immune system is working. It’s doing it’s best to prevent an infection by healing the injury caused by the mosquito piercing your skin. If a mosquito was infected with a virus or bacteria, it may transfer those microbes into your body.  This is also why your immune system would be kicked into gear.

What Happens if I Itch Too Much?


Even though scratching the area where you got bitten might feel good for a few moments, it’s a really bad idea to scratch your mosquito bites. As you scratch, you actually end up making the itchy sensation even itchier since more histamine and inflammation are produced as a result of you itching the bite.

If you continue to itch with your fingernails and scratch hard enough, you could break the skin surface and end up with a bacterial infection, which must be treated without delay! Signs of a bacterial infection at the bite location would include pain, increased swelling, and more redness. If you’re worried that you may have gotten an infection as a result of scratching your mosquito bite, consult with a physician to get further help. You may need antibiotics  to clear up the infection.

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Solutions to the Itching


It’s clear that itching your mosquito bite is a really bad idea. You don’t want to deal with any infections or more problems, but you still want to get rid of the horrible itching sensation. What are some things you can do to stop the itching and feel better then?

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Before you apply or take anything, make sure you first wash your mosquito bite marks with soap and water to clean the surface of your skin to prevent an infection.

• As mentioned earlier, your itching is mainly due to histamine being released in high amounts. To lessen histamine’s itchy impact, you could take an oral antihistamine like Zyrtec, Claritin, or Allegra. Any of these over-the-counter drugs can help lessen your itching before and after you get bitten.

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• You can also try a topical antihistamine cream like Benadryl (Diphenhydramin), or hydrocortisone, a steroidal cream that’s different from an antihistamine but also works to reduce the inflammation, swelling, and itching of your mosquito bite.

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• Calamine lotion (Caladryl) and regular toothpaste are other options that can temporarily lessen your itching.

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Why Do Mosquito Bites Itch? Natural Alternatives

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• Applying essential oils like tea tree, lavender, or chamomile directly onto the bite marks. They can serve as natural antihistamines, reducing the itching by calming inflammation.

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• Aloe Vera gel could also help sooth your itching, since it’s a well known anti-inflammatory and can help fight against infections too.

• If you’re okay with being a little sticky, try applying a dash of raw honey or Manuka to the itchy area. Honey acts as a natural antibiotic and can also reduce the inflammation of your mosquito bite, which can lessen the itchy sensation. Even if the honey doesn’t end up reducing your itching, it’s still useful in preventing bacterial infections.

• Even something as simple as applying a cold compress or icepack onto the itchy area could provide you with some relief, since the cold will reduce inflammation and control the swelling. However, don’t leave the ice too long since that can damage your skin.

With itchy mosquito bites, it’s only a matter of time before the itching goes away on its own. You’ll typically have to wait a few days to a week for the itching and swelling to completely disappear.

Do All Mosquitoes That Bite Carry Diseases?

Thankfully no (we’d all be dead by now if that were the case)! There are some mosquitoes that bite us which do carry deadly diseases however.

Even though a mosquito bite can be itchy, it’s not the bite itself that kills you, but rather the deadly microbes they can carry which would cause serious harm if a mosquito bites and transmits the microbe to you.

The mosquitoes that transmit diseases (in the form of viruses, bacteria, or protists) come from three groups, which I call “the deadly three”:

Anopheles, responsible for spreading malaria.

Culex, which transmits West Nile virus (The most common mosquito infection in the U.S), St. Louis encephalitis, Western equine encephalitis (WEE), and several others.

Aedes, where two species in this genus, A. albopictus and A. aegypti, are mainly responsible for transmitting viruses which lead to illnesses like Zika, dengue, yellow fever, chikungunya, and Eastern Equine Encephalitis (EEE).

If you live in the U.S, you’d mainly have to worry about Culex and Aedes mosquitoes, since malaria spread by Anopheles was wiped out from the U.S several decades ago. People who are sick with malaria in the U.S usually bring it back from countries where malaria is prevalent (in tropical areas).

And thankfully, most mosquito-borne diseases aren’t contagious, meaning that if one person is sick, you usually can’t get sick directly from that person. You would only get sick in cases where a mosquito is previously infected with the pathogen and they bite you.

How to Prevent Mosquito Bites and Possible Infection

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With a few key precautions, you can make sure that you’ll have a good time outside while avoiding getting bit, and possible illnesses associated with mosquito bites.

If you’re engaging in any outdoor activities near your house, the top three ways for lowering the chance of getting bitten are:

• Removing any source of standing water. That’s the critical piece in lowering the mosquito population near your home, since mosquitoes complete their life cycle (from egg to adult) wherever there is an area of stagnant water. This means you need to empty any open buckets, containers, or pools periodically (especially after a rainfall) to prevent mosquitoes from breeding.

• Make sure you have window and door screens put in place to prevent mosquitoes from entering your house.

• Consider planting some natural mosquito-repelling plants like lavender, citronella grass, and rosemary in your back or front yard.

And if you’re going for a walk or hike in an area with a lot of vegetation and standing water (think swamp, pond, or lake), then follow these tips:

Why Do Mosquito Bites Itch? Follow These Tips


• Be careful especially around dawn and dusk when mosquitoes are most active. In those times, wear long-sleeved clothing that covers your arms and legs, since mosquitoes usually can’t bite through clothing unless it’s very thin.

• Most websites will recommend using DEET sprays since it’s one of the most effective mosquito repellents. Unfortunately DEET can be quite toxic to humans over the short and long term. If you have to use DEET, then try to stick with 30% or less.

• There are non-DEET organic repellent alternatives. These involve essential oils like citronella and lemongrass, although they usually aren’t as effective as DEET.

As someone who’s a mosquito magnet, I’ve tried many natural mosquito repellents over the years. With a lot of frustration, I haven’t had much success with natural products lasting for enough time. If you’re okay with reapplying frequently, it’s a decent alternative to using DEET.

And as an entomologist, it’s one of my life goals to come up with a truly effective mosquito repellent solution. There are many products out there on the market today. But, almost all of them are short-term fixes to a problem that requires a more sophisticated approach.

For 2021 and beyond, stay tuned for future product updates from Trappify. Hopefully your mosquito problems will soon come to an end!

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