Understanding a Mosquito Allergy: Symptoms, Diagnosis, and Treatments

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Mosquito bites are annoying, but is it possible to have a mosquito allergy? To understand how you might be exposed to an allergen that triggers a reaction, let's look at what happens when you get bit.

Mosquitoes are flying, biting insects that are closely related to flies and gnats. Only the female mosquito feeds on humans, and she needs a blood meal in order to produce eggs. During a feeding, the female mosquito bites the human skin and injects saliva. The saliva contains various proteins that prevent the blood from clotting, as well as proteins that keep the blood flowing into the mosquito’s mouth.

Reactions to Mosquito Bites

Many of the mosquito saliva proteins can cause immune reactions, including allergic reactions. Typically, however, most people have a variety of reactions to mosquito bites, and the symptoms change over time, depending on the number of bites a person receives. These reactions can include both immediate and delayed swelling, and itch around the bite area. These reactions tend to decrease in frequency after being bitten by mosquitoes over many years.

Generally, people with the above-described reactions are not diagnosed as being “mosquito allergic." This term is reserved for people with more severe or unusual reactions, such as those described below.

More Severe Reactions to Mosquito Bites: "Skeeter Syndrome"

Reactions more severe than the typical itchy red bump experienced by most people as a result of a mosquito bite occur less commonly. These may result in blistering rashes, bruises, or large areas of swelling at the bite sites. People who experience extremely large areas of swelling after a mosquito bite (such as swelling of most of an arm or leg, for example) have been dubbed as having "Skeeter Syndrome."

In rare situations, some people may experience anaphylaxis (the most serious type of allergic reaction) after being bitten by mosquitoes. Other people may have experienced whole body urticaria and angioedema (hives and swelling) or worsening of asthma symptoms after being bitten. Typically, these symptoms occur within minutes after a mosquito bite, compared to Skeeter Syndrome, which may take hours to days to occur.

Who Is at Risk for Mosquito Allergy?

People who are at higher risk of developing an allergy to mosquito bites include:

  • Those with frequent outdoor exposure, such as outdoor workers or frequent outdoor exercisers
  • Those with low natural immunity to mosquitoes, such as young children and visitors to a new area where they have not been previously exposed to the type of mosquito present
  • Those with certain immunodeficiencies, such as AIDS or certain cancers (such as leukemias and lymphomas)

How Is Mosquito Allergy Diagnosed?

The diagnosis of mosquito allergy is based on a positive skin test or RAST using mosquito whole-body extract. Testing for mosquito allergy should only be performed in people who have a history of reactions more severe than the typical small, red, itchy bumps experienced by most people. That said, commercially available allergy testing is apparently only able to identify 30 to 50 percent of those who have a true mosquito allergy.

How Is Mosquito Allergy Treated?

The treatment of mosquito allergy falls into three different categories: the treatment of local reactions, the treatment of severe reactions (anaphylaxis,) and prevention. Let's look at each of these separately:

Local Reactions: Most localized reactions can be treated with the use of topical corticosteroids, such as hydrocortisone cream, as well as with oral antihistamines. In fact, Zyrtec (cetirizine) has been shown to reduce local reactions to mosquito bites when taken before being bitten. Some have suggested that those with mosquito allergy use Zyrtec on a daily basis during the summertime when mosquito bites are most likely to occur. Make sure to talk to your doctor before you make a regular practice of this, as any medication may have side effects.

Anaphylaxis: The treatment of anaphylaxis, which only rarely occurs as a result of a mosquito bite, should be treated in much the same way as anaphylaxis to insect stings. with severe reactions such as this, your pediatrician may recommend carrying an EpiPen as well as other measures to decrease the likelihood of a reaction. Allergy shots, using mosquito whole-body extract, have been shown to reduce severe reactions in people with a true allergy to mosquitoes.


The prevention of mosquito bites is the main goal for those with mosquito allergy. These measures include:

  • Avoiding areas infested by mosquitoes (such as swamps and tall grassy areas.)
  • Removing or treating areas of standing water (empty out or treat swimming pools with chlorine.)
  • Wearing long-sleeved shirts and pants if exposure to areas containing mosquitoes is planned.
  • Avoid cologne and scented lotions when going out-of-doors.
  • Applying a commercially-available mosquito-repellant on exposed skin, such as those containing DEET (N, N-dimethyl-3-methyl-benzamide). DEET in concentrations of 10 to 30 percent can safely be used on the skin of children older than 2 months of age. Learn more about the best insect and mosquito repellents for kids (and adults.)
  • Treating clothing, camping tents and other fabric with permethrin (an insecticide), but do not apply directly to the skin.
  • Also, since mosquitoes are attracted to body odor, skin temperature, and carbon dioxide production, the limitation of strenuous exercise and sweating when in areas infested by mosquitoes may reduce the number of bites.

Bottom Line on Mosquito Allergy

Thankfully, annoying and itchy reactions to a mosquito bite are much more common than a true mosquito allergy. Those who have a true allergy should see an allergist and talk about the best treatments for their particular symptoms. In particular, anyone who has a severe allergic reaction should be prepared to recognize anaphylaxis and consider allergy shots.

What we did not bring up here is a reason to protect yourself against mosquito bites whether or not you have an allergy. While malaria, yellow fever, and other illnesses are uncommon in most developed countries, diseases such as West Nile virus (and its variants) may occur anywhere. Check out these tips on how to avoid mosquito bites no matter where you live.

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