Understanding Mosquito Bite Allergy

Is It Skeeter Syndrome?

A red bump that is itchy for several days before disappearing is the typical calling card of a mosquito bite. But for people with a mosquito bite allergy, symptoms are more severe and can include rash, large areas of excessive swelling, and even bruising.

Also known as "skeeter syndrome," this inflammatory reaction is pretty rare. For those who are allergic to mosquitoes, however, it can have a big impact on their ability to enjoy the outdoors. Intense itching can even end up causing a skin infection.

An illustration with information about symptoms of a mosquito bite allergy

Illustration by Jessica Olah

This article will help you learn to tell the difference between a normal mosquito bite and skeeter syndrome. It will also explain how skeeter syndrome is diagnosed and treated.

Normal Mosquito Bite vs. Skeeter Syndrome

A normal reaction to a mosquito bite looks different from skeeter syndrome. Skeeter syndrome produces much more severe symptoms.

Normal Mosquito Bite

Most people have a variety of responses to mosquito bites. The symptoms may even change over time. For example, they may happen less often if you are bitten many times over many years.

These reactions can include:

  • Immediate or delayed swelling
  • Itch around the bite area
  • Bleeding or oozing if scratched

If you have these reactions, you probably don't have a mosquito bite allergy. The term allergy is reserved for people with more severe or unusual responses.

Skeeter Syndrome

An allergic reaction to a mosquito bite looks like:

  • Large areas of swelling at the bite site
  • Blistering rashes
  • Bruises
  • Welts
  • Low-grade fever
  • Swollen lymph nodes

These reactions tend to occur in the first few hours after the bite.

Some people have vast areas of swelling after a mosquito bite. For example, the swelling might include most of an arm or leg.

Mosquito bites can also become infected, typically because of scratching to ease discomfort. Signs of infection include redness and warmth at the bite site. If you have any of these symptoms, see a healthcare provider.

Skeeter syndrome itself isn't life-threatening and does not cause long-term problems, but a skin infection should be dealt with promptly.

Anaphylaxis, the most severe type of allergic reaction, is a very rare reaction to a mosquito bite. It requires immediate medical attention. Symptoms of anaphylaxis may include trouble breathing, swelling of the tongue, lips or throat, hives, and feeling faint.

These severe mosquito bite allergy symptoms typically occur within minutes after a mosquito bite, but they can take hours to appear.

Who Is at Risk for Skeeter Syndrome?

You're obviously more at risk for a bite if you're in an environment that is conducive to mosquito breeding. This happens once temperatures are regularly above 50 and ideally 70 degrees. The warmer and wetter the area, the more active the mosquitoes.

Those who may be at higher risk for an allergic reaction to a mosquito bite include:

  • People who work outside or frequently exercise outdoors
  • Young children
  • People not previously exposed to the local mosquito type
  • People who are immunocompromised, such as those with HIV or cancer

When the mosquito feeds, it pierces your skin and injects saliva. If you have skeeter syndrome, your body incorrectly views proteins in that saliva as harmful and the immune system responds in kind, resulting in an allergic reaction.

Mosquitos Attraction

Only the female mosquito feeds on humans for a blood meal to produce eggs. They can detect the carbon dioxide in the air that humans exhale. They are also attracted to the odors in human sweat. This is what helps them find people to bite.

Diagnosing Mosquito Bite Allergy

If you have had a severe reaction to a mosquito bite it is important to see an allergist, a doctor who specializes in allergic conditions like this.

Diagnosing a mosquito bite allergy is based on a positive skin test, or radioallergosorbent test (RAST). This test purposefully exposes you to an extract made from the bodies of mosquitoes to see if you have a reaction.

Testing is only considered necessary for people who have a history of severe reactions. People who get the typical small, red, itchy bumps after being bitten by a mosquito do not need a test.

Unfortunately, mosquito bite allergy testing can only identify 30% to 50% of true mosquito bite allergies.

If you are diagnosed with a mosquito bite allergy, your allergist can develop a treatment plan and/or prescribe medication that can protect you in the event of an anaphylactic reaction.

How is Skeeter Syndrome Treated?

Treatment for an allergic reaction to a mosquito bite is focused on treating the bothersome symptoms of local reactions and, if applicable, working to mitigate the potential for and extent of severe reactions.

It also involves establishing a plan to treat life-threatening body-wide reactions, should they occur.

At-Home Treatments for Mosquito Bites

A local reaction is confined to one part of the body. There are many ways to treat localized reactions at home. These include:

  • Topical corticosteroids like hydrocortisone cream
  • Oral antihistamines
  • Applying ice to reduce swelling, redness, and soothe the itch
  • Elevation to reduce swelling
  • Applying cooked oatmeal to reduce itching and swelling
  • Calamine lotion to help soothe the itch

When taken before a bite, Zyrtec (cetirizine) has been shown to reduce local reactions to mosquito bites. Similarly, daily Claritin (loratadine) may help reduce reactions in children.

Taking one of these medications every day during prime mosquito months may help people with skeeter syndrome. However, any medication can have side effects, so be sure to ask your healthcare provider before you decide to try this.

Pregnant people with skeeter syndrome should take care to avoid mosquito bites. This is because not all over-the-counter (OTC) remedies are safe for use during pregnancy. Always discuss your options with your healthcare provider.

Allergy Shots

Severe cases of skeeter syndrome may benefit from immunotherapy, a form of allergy treatment where you receive shots containing small amounts of the allergen.

The goal of this treatment is to help your body get used to the allergen so you'll no longer be sensitive to it. Over time, it can improve your symptoms.

There is some evidence that allergy shots may reduce severe reactions to mosquito bites. However, at this time they are not a widely accepted treatment for any type of mosquito bite allergy. This is mostly because the research is limited and the treatment isn't standardized.

Epinephrine for Anaphylaxis

Your practitioner may recommend carrying an EpiPen, which contains a manmade version of the stress hormone epinephrine.

Healthcare providers often prescribe this injectable medication for people who have a history of severe allergies. When given, epinephrine can stop symptoms of anaphylaxis.

Always call 911 after using an EpiPen. Emergency medical personnel will decide if you need a second dose.

Preventing Mosquito Bites

Preventing mosquito bites is the best strategy for those with mosquito bite allergies.

When you are planning to be outdoors, consider the following measures:

  • Try not to be outside at dusk or dawn, when mosquitoes are most active
  • Avoid swampy and tall grassy areas
  • Remove or treat areas of standing water (e.g., birdbaths)
  • Wear long-sleeved shirts and pants
  • Avoid wearing perfumes and scented lotions
  • Treat clothing, camping tents, and other fabric with the insecticide permethrin (do not apply directly to the skin)
  • Limit strenuous exercise and sweating during peak mosquito times

Insect Repellants to Protect Against Mosquito Bites

Use a mosquito-repellant containing DEET (N, N-dimethyl-3-methyl-benzamide).

DEET can be safely used in concentrations of 10% to 30% on children older than 2 months of age. Note that repellents can cause side effects, including eye irritation, dry skin, rash, and possible allergic reaction. Use the lowest concentration that works for you and reapply as needed.


An allergy to mosquito bites is called "skeeter syndrome." If you have skeeter syndrome, you may experience blistering rashes, bruising, and large areas of swelling. In addition, some people may develop anaphylaxis, the most severe type of allergic reaction.

You can treat mosquito allergies at home with antihistamines and topical creams. People with skeeter syndrome should also avoid mosquito-infested areas, wear long sleeves and repellent, and avoid activities like exercise that may attract mosquitoes.

Frequently Asked Questions

  • What blood type do mosquitoes like?

    Studies have found that mosquitoes prefer to feed on people with type O blood. The reasons for this are unclear. Blood type doesn't seem to affect how many eggs a female can lay.

  • Can mosquitoes bite through clothes?

    Yes. Mosquitoes can bite through thin fabric and skin-tight fabric, including T-shirt fabric, leggings, and sometimes even denim. Loose-knit sweaters also don't offer much protection.

  • What does skeeter syndrome look like?

    People with skeeter syndrome usually have extreme itching and swelling. The swelling may affect an entire limb. There may also be blisters that ooze. Sometimes the person's eyes will swell shut.

12 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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By Daniel More, MD
Daniel More, MD, is a board-certified allergist and clinical immunologist. He is an assistant clinical professor at the University of California, San Francisco School of Medicine and currently practices at Central Coast Allergy and Asthma in Salinas, California.