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These Are the Signs of a Mosquito Bite Allergy, According to a Doctor

The reaction is bigger than the typical itchy bump.
Mosquito on Hand
A mosquito bite allergy can cause a more severe reaction.Jonathan Austin Daniels / Getty Images

Summer nights can elicit sweet memories of a cool evening breeze or the smoky scent of a campfire. But the hundreds of mosquitoes invading your personal space probably don’t make the cut into treasured memory territory. What’s worse? When you have a bonafide mosquito bite allergy.

Mosquitoes are arguably among the peskiest of insects, with over 3,500 different types existing around the world, according to the Centers for Disease Control and Prevention (CDC). Unfortunately for humans (and many animals), almost all of those species interact with us through one activity: blood feeding.

Female mosquitoes bite humans and animals so that they can produce eggs for reproduction. During the feeding process, the female mosquito uses a mouthpart called the proboscis—which is also used to feed on flowers—to pierce the skin and feed on the blood. As she is feeding, the mosquito injects her saliva back into the skin to keep the blood from clotting.

When the saliva enters our skin during the feeding process, it causes the reaction we commonly associate with mosquito bites. Most reactions start with a small patch of redness or swelling at the site of the bite. Within a matter of minutes, the bite can begin to itch or change colors, becoming darker, harder, or more swollen over the course of the next few days, according to the CDC.

For a small (unlucky) group of people who have a true mosquito bite allergy, these symptoms can be much more severe and take weeks to resolve. Ahead, we’ll explore what you need to know about mosquito bite allergic reactions, including how to limit your exposure to mosquitoes and protect yourself.

What is a mosquito bite allergy, exactly?

“Mosquito bites are caused by an immune response to mosquito saliva,” Kara Wada, MD, a clinical assistant professor in the division of allergy immunology at The Ohio State University Wexner Medical Center and owner of The Crunchy Allergist, tells SELF. Although most people experience a mild immune response, those with a mosquito bite allergy experience a much different reaction.

“Some people will develop more significant reactions called large local reactions, sometimes termed ‘skeeter syndrome,’” says Dr. Wada. She explains that these reactions result from a stronger immune system response than usual, a response that can cause symptoms—like swelling and redness—which last longer than your typical mosquito bite reaction.

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What are the most common mosquito bite allergy symptoms?

A normal mosquito bite can initially appear swollen, hot, and itchy. If you scratch the bite—as most of us can’t resist doing—you might notice that it becomes even more swollen and itchy. Eventually, the bite will turn into a raised, hard bump (or bumps, depending on how many mosquitoes decided to feast) that disappears within the following days or weeks.

A mosquito bite allergy causes a reaction that both looks and feels more severe than your typical mosquito bite reaction. When you’re allergic to a mosquito bite, the reaction tends to develop more quickly. You might also experience:

  • Hives or a large rash that spreads across your body
  • Painful, blistering lesions
  • Low-grade fever
  • Swollen lymph nodes
  • Joint swelling1

While most of these symptoms will subside with at-home treatment, there are some symptoms that shouldn’t be ignored. “Symptoms that would be concerning for a systemic or whole-body allergy include generalized hives or, rarely, anaphylaxis—a group of symptoms that can include difficulty breathing, swelling, hives, and passing out,” explains Dr. Wada. Anaphylaxis is a life-threatening allergic reaction and requires immediate medical attention and the use of an epinephrine auto-injection.

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What causes a mosquito bite allergy?

According to an older study published in the International Archives of Allergy and Immunology, mosquito bites develop as a response to certain components in mosquito saliva. When the saliva enters the bloodstream, the body produces antibodies to the proteins inside that saliva, resulting in an immune reaction.1

Generally, sensitization—or the process by which an allergy develops—to mosquito bites happens over the course of multiple bites. Upon initial exposure to a specific species of mosquito, a person might not notice a reaction at all. But over time, if that person is continuously bitten by the same species, the body can become sensitized, and an allergy can develop.1

Unfortunately, it’s hard to pinpoint exactly why some people develop an allergy to mosquito bites. One 2021 review published in Allergology International suggests that it could be due to differences in susceptibility between people, which can be affected by everything from the species of the mosquito to the number of times someone is bitten, among other factors.2

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What are the risk factors for a mosquito bite allergy?

“Studies have indicated that those that are frequently outdoors, young children, and newcomers or visitors to an area with a different species of mosquito may have more robust local reactions,” shares Dr. Wada.

One of the reasons that younger children and visitors may be more likely to experience a severe reaction to mosquito bites is due to their lack of exposure—as it turns out, being bitten more can actually desensitize the body. One 2017 study published in the Asian Pacific Journal of Allergy and Immunology found that younger children were more likely to experience both delayed and immediate mosquito bite reactions, while older children seemed to experience less severe reactivity when bitten.3 “Interestingly those with immune deficiencies may have increased reactions too,” adds Dr. Wada. 

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How do you treat an allergic reaction to mosquito bites?

Unless you’re having a severe allergic reaction to a mosquito bite, most mosquito bite allergy symptoms can be handled at home. “Using over-the-counter, long-acting oral antihistamines like loratadine, cetirizine, or fexofenadine can help decrease itching—as can a topical steroid cream,” says Dr. Wada. Simply applying ice and taking ibuprofen can also help with itching and swelling.

Even if you’re treating your symptoms at home, it can still be helpful to touch base with your doctor on what options might work best for you and your specific symptoms. Though Dr. Wada does recommend avoiding one topical medication—diphenhydramine, a common antihistamine found in Benadryl products—because it may lead to an allergic skin rash if used for a long period of time.

If your symptoms aren’t responding to traditional over-the-counter antihistamines or steroid creams, consider consulting with a specialist who can prescribe a stronger medication. “More often, a prescription-strength cream may be much more effective,” Dr. Wada says. For people with a true systemic allergic reaction to mosquito bites, immunotherapy, or allergy shots, may also be considered. With immunotherapy, the allergen is introduced in small amounts. Over time, the body becomes desensitized to the allergen.

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When is a mosquito bite allergy reaction an emergency?

If you notice any of the symptoms of anaphylaxis, such as wheezing, dizziness, or fainting, after being bitten by a mosquito, it’s important to seek medical attention right away.

Dr. Wada also mentions that there’s another potential mosquito complication that would warrant medical attention. “Scratching mosquito bites can open up the skin to developing a secondary bacterial infection called cellulitis,” she warns. “If this is left untreated it can progress and be dangerous.”

If you’re experiencing any swelling, redness, or pain that continues to worsen within the days after the initial bite or is accompanied by symptoms like a fever or chills, Dr. Wada recommends seeing a medical professional right away.

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How to prevent mosquito bites

“Prevention of bites is the best treatment,” explains Dr. Wada, but of course, that’s not always easy to accomplish. The CDC recommends a few tips to keep in your back pocket:

Create an unwelcome environment for mosquitoes.

You’ll often find mosquitoes in warm, damp places, so one of the best things you can do inside your home is to keep it cool and clean. “Make sure screens on windows and doors are well maintained,” recommends Dr. Wada, as this can help keep mosquitoes from entering your home. And whenever possible, try to keep your home clear of any standing water containers that may attract mosquitoes.

Wear clothing that covers and protects your skin.

By the time you even realize you’re in the presence of a mosquito, there’s a high chance it’s already beelined for your uncovered skin. Even though it can be hard to cover up in the middle of summer, wearing long-sleeve shirts and long pants can help protect your skin from mosquito bites, especially if you’re camping. “You can also find clothing and camping gear that is made with fabric treated with permethrin,” says Dr. Wada, which is a safe and effective EPA-approved insecticide. You can also buy permethrin and treat clothing yourself.

Follow EPA recommendations for mosquito repellants

When it comes to mosquito repellants, EPA-registered products are the safest and most effective options when used properly. While there are plenty of choices among EPA-approved repellents, Dr. Wada mentions that DEET and picaridin are particularly effective. “Citronella and lemon eucalyptus oil may have some effect, but are relatively short-acting, lasting 20 minutes and two hours, respectively,” she says.

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Sources:

  1. American Academy of Allergy, Asthma, and Immunology, Take a Bite Out of Mosquito Stings
  2. International Archives of Allergy and Immunology, Mosquito Allergy: Immune Mechanisms and Recombinant Salivary Allergens
  3. Allergology International, Hypersensitivity to Mosquito Bites: A Versatile Epstein–Barr Virus Disease With Allergy, Inflammation, and Malignancy
  4. Asian Pacific Journal of Allergy and Immunology, Mosquito Allergy in Children: Clinical Features and Limitation of Commercially-Available Diagnostic Tests

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