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Mosquito bites

Medically reviewed by Last updated on Oct 26, 2022.


Mosquito bites are the itchy bumps that form on the skin after mosquitoes feed on your blood. The bumps usually go away without treatment in a few days. Some mosquito bites may get very swollen, sore and inflamed. This type of reaction, sometimes called skeeter syndrome, is most common in children.

Mosquito bites can cause severe illnesses if the insects carry certain viruses or parasites. Infected mosquitoes can spread West Nile virus, Zika virus, and the viruses that cause malaria, yellow fever and some types of brain infection.


Mosquito bites often happen on parts of the body that aren't covered by clothing. Symptoms include:

A severe reaction to mosquito bites can cause:

Children are more likely to have a severe reaction than are adults.

When to see a doctor

Contact your health care provider if the mosquito bites seem to occur with warning signs of a serious condition. These might include a high fever, severe headache, body aches and signs of infection.


Mosquito bites are caused by female mosquitoes feeding on your blood. As a biting mosquito fills itself with blood, it injects saliva into your skin. The saliva triggers an immune system reaction that results in the classic itching and bump.

Mosquitoes are attracted to smells, such as from sweat, floral scents and exhaled carbon dioxide.


Scratching bites can lead to infection.

Mosquitoes can carry the viruses that cause certain diseases, such as West Nile virus and the viruses that cause malaria, yellow fever and dengue fever. The mosquito gets a virus or parasite by biting an infected person or animal. Then when it's biting you, the mosquito can transfer that virus or parasite to you through its saliva. West Nile, dengue fever and some types of encephalitis occur in the United States. Other diseases, such as malaria and yellow fever, are far more common in tropical areas of the world.


Mosquitos bite during both day and night, and they can live indoors. You can take several steps to protect yourself from mosquito bites.

Avoid and exclude mosquitoes

Limit exposure to mosquitoes by:

Use insect repellent

Use insect repellent when mosquitoes are active. The most effective insect repellents in the United States include one of these active ingredients:

These ingredients temporarily repel mosquitoes and ticks. DEET may offer longer lasting protection. Whichever product you choose, read the label before you apply it. If you're using a spray repellent, apply it outdoors and away from food. You may need to reapply it 6 to 8 hours later if you're still in an area where mosquitoes are active.

If you're also using sunscreen, put it on first, about 20 minutes before applying the repellent. Avoid products that have both sunscreen and repellent, because you'll likely need to reapply sunscreen more often than repellent. And it's best to use only as much repellent as you need and to wash your hands after applying it.

Used according to package directions, these products are generally safe for children and adults, with a few exceptions:

Treat clothing and outdoor gear

Permethrin is an insecticide and insect repellent used for added protection. This product is made to use on clothing and outdoor gear, not skin. Check the product label for instructions. Some sporting goods stores sell clothing pretreated with permethrin. Don't wash bed nets or set them in sunlight, as this breaks down permethrin. Clothing sprayed with permethrin can offer protection for two washings and up to two weeks.

Use protective clothing and gear

Weather permitting, wear a hat, long-sleeved shirts and long pants.

Take preventive medicine

Get vaccinations or take preventive medicine that your health care provider has suggested.

Think about whether you tend to have large or severe reactions to mosquito bites — skeeter syndrome. You might want to take a nondrowsy, nonprescription antihistamine when you know you'll be exposed to mosquitoes.

Reduce mosquitoes around your home

Get rid of standing water, which mosquitoes need to breed. Take these steps to keep your house and yard free of mosquito pools:


Your health care provider will likely be able to diagnose mosquito bites simply by looking at them and talking with you about your recent activities.

The inflamed, itchy, painful swelling referred to as skeeter syndrome is sometimes mistaken for a bacterial infection. Skeeter syndrome is the result of an allergic reaction to proteins in mosquito saliva. There's no simple blood test to detect mosquito antibodies in blood. Antibodies are substances the body produces during an allergic reaction.

Mosquito allergy is diagnosed by determining whether the large areas of swelling and itching occurred after mosquito bites.

Lifestyle and home remedies

Most mosquito bites stop itching and heal on their own in a few days. These self-care tips may make you more comfortable.

Preparing for an appointment

You won't need to see your doctor for a mosquito bite unless you develop a fever or other symptoms that sometimes develop after such bites.

Here's some information to help you get ready for your appointment.

What you can do

Before your appointment, make a list of:

If you're having signs and symptoms you think might be related to a mosquito bite, some basic questions to ask your doctor include:

What you can do in the meantime

If itching is a problem, try a nonprescription, nonsedating antihistamine such as cetirizine (Children's Zyrtec Allergy, Zyrtec Allergy, others).

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