Mosquito Bite Symptoms, Causes & Treatment Options
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Mosquito bites are bites from flying insects that feed on blood. They are common during the summer or in warmer climates, at dawn or dusk, and near bodies of water.
What is a mosquito bite?
Mosquito bites are bites from flying insects that feed on the blood of animals, including humans. Mosquito bites are more common during the summer or in warmer climates, at dawn or dusk, and near bodies of water.
In most cases, mosquito bites will cause a local skin reaction that gets better on its own over days or weeks. Less commonly, children may develop recurrent itchy bumps called papular urticaria. In rare cases, some people may develop severe allergic reactions to mosquito bites. In addition, mosquitoes may carry viruses that cause encephalitis, Chikungunya Fever, and Zika virus.
The diagnosis is made by history and exam. Treatment options include washing the bite and using ice or cold packs or topical medications to relieve itching. More severe reactions may require oral allergy medications or epinephrine injection.
You can safely treat this at home. In most cases, an oral antihistamine like Benadryl or anti-itch lotion will provide complete relief.
Mosquito bite symptoms
Symptoms of mosquito bites include local skin reactions, possible recurrent skin bumps, as well as symptoms suggesting a systemic allergic reaction. Sometimes mosquitoes can carry diseases that can be transmitted to the person bitten. These illnesses can cause a variety of symptoms that develop after the bite. Some diseases that can be carried by mosquitoes in the United States include encephalitis, Chikungunya fever, and Zika virus.
Local skin reactions
Symptoms of local skin reactions can be described as:
- A red, painful, itchy bump
- Developing within 20 minutes of the mosquito bite
- Increasing size: The bite may get larger over two to three days and slowly gets better over days or weeks. Some people may get large local reactions that can be 2 to 10 cm in diameter.
- A bump that hardens over time
- Fluid-filled bumps, blisters, or bruises: In rare cases, some people may develop fluid-filled bumps, blisters, or bruising at the site of the bite.
Recurrent skin bumps
Recurrent skin bumps can occur in children in a condition known as papular urticaria. This is caused by the immune system reacting to the bite. It can be described as:
- Itchy, red bumps
- Developing on the arms, legs, scalp, and back
- Long-lasting: These bumps may occur days or weeks after the initial mosquito bite, and can last for months or years and can occur repeatedly.
- Self-resolving: In most cases, these bumps will go away on their own.
Systemic allergic reaction
In rare cases, some people may develop a widespread allergic reaction to mosquito bites throughout their entire body. This can cause deadly symptoms if not treated emergently, including:
- Itchy red bumps all over the body
- Swelling around the face and throat
- Trouble breathing
- Hearing a high-pitched sound during breathing
- Nausea, throwing up, or even passing out
Symptoms of Viral Encephalitis
This is an infection of the brain caused by a virus carried by the mosquito. Specific viruses carried by mosquitoes in the United States include West Nile Virus, St. Louis Encephalitis, and La Crosse Encephalitis. These infections can cause:
- Nausea or throwing up
- Numbness or weakness
Symptoms of Chikungunya Fever
Outbreaks of this virus have occurred in Africa, Asia, Europe, and the Indian and Pacific Oceans. In 2013, it was reported in the islands of the Caribbean. It is important to be mindful of exposure to this virus if you travel to any of these areas, or come in contact with someone who has. Symptoms last for about a week, and include:
- High fever
- Joint pains: Usually multiple joints are affected on both sides of the body.
- Muscle aches
- Abdominal pain
Symptoms of Zika Virus
Like Chikungunya fever, Zika is a threat internationally, but not necessarily in the US. However, women who are pregnant and infected with Zika virus can pass the virus to their babies, who can then develop problems after birth. Microcephaly is a main congenital problem in which the head is abnormally small and the brain cannot properly develop. Symptoms of Zika include:
- Low fever
- Joint pains
- Muscle aches
- Eye irritation
- Abdominal pain or diarrhea
Mosquito bite causes
Mosquito bites are caused by flying bugs called mosquitoes that bite humans to feed on their blood. Mosquitoes are found worldwide and are more common in warm and wet environments and during certain times of the day. Risk factors for getting a mosquito bite include:
- Being outside in the summer or in warmer climates
- Being outside at dawn or dusk
- Being near bodies of water: Mosquitoes reproduce near bodies of standing water such as ponds or lakes, so spending a lot of time near areas of water can increase your chances of getting a mosquito bite.
- Being outside without protective clothing or bug spray
Treatment options and prevention for mosquito bite
Mosquito bites will usually get larger over two to three days and then slowly get better on their own in a few days or weeks. Some reactions to the mosquito bite, such as "papular urticaria," can last for months or years. However, if you develop lots of itchy bumps or have trouble breathing, you need to see a physician right away. You should also seek medical attention if you are severely ill and believe you have contracted a mosquito-borne illness. Treatments can also include at-home remedies for less severe cases.
At-home remedies to soothe less severe bites and reactions include:
- Washing with soap and water: This can help remove irritating substances from the bite and prevent infections.
- Ice or cold pack: Placing ice or a cold pack on the bite can reduce swelling and make it less uncomfortable.
- Topical creams, gels, or lotions: Over-the-counter creams, gels, or lotions can help reduce itching and make the bite less uncomfortable. Look for products that contain calamine, pramoxine, or menthol.
- Oral allergy medications: If the area is very itchy or if you have a lot of itchy areas, you can use some over-the-counter allergy medications that contain antihistamines, which help reduce itching. Examples include Claritin, Zyrtec, and Allegra.
- Epinephrine injection: If you develop any trouble breathing after a mosquito bite, you need to use an epinephrine injection ("EpiPen") right away or go to the emergency room. People who have had severe allergic reactions in the past will be given an EpiPen by their physician along with instructions on how to use it.
Prevention is an important part of managing mosquito bites. Effective ways to reduce the risk of getting a mosquito bite include:
- Wearing long-sleeved shirts and pants when going outside: This helps cover up your skin and can reduce the risk of getting a mosquito bite.
- Use insect repellents: Using a natural insect repellent registered with the Environmental Protection Agency can reduce the risk of getting a mosquito bite. Choose an insect repellent that contains DEET, picaridin, IR3535, oil of lemon eucalyptus, para-menthane-diol, or 2-undecanone.
- Use window and door screens: This helps keep mosquitoes out to reduce the risk of getting a mosquito bite. Sleeping under a mosquito bed net can also reduce the risk of getting a bite.
When to seek further consultation for a mosquito bite
If you notice an abnormal reaction to a mosquito bite in either yourself or your child, or become ill, you should seek medical attention.
If you develop any symptoms of an allergic reaction
You should go to the emergency room right away if you experience itchy red bumps all over your body, swelling around the face and throat, trouble breathing, hearing a high-pitched sound during breathing, nausea or throwing up, or passing out. After you are treated, you will need to see an allergy doctor to learn about how to prevent and manage severe allergic reactions in the future.
If bite increases in size and/or pain
You should see your primary care physician if the mosquito bite gets bigger, more painful, or doesn't go away on its own in a few weeks. You should also see your primary care physician if the area of the bite gets red and you get a fever. That's a sign that it could be getting infected, and your physician will be able to prescribe the appropriate treatment.
If you become ill
If you develop any symptoms that suggest you may have gotten a disease carried by the mosquito, such as a fever, headache, nausea, throwing up, joint pains, numbness, or weakness, you should see your primary care physician, who may be able to diagnose any diseases you may have.
Questions your doctor may ask to determine mosquito bite
- Any fever today or during the last week?
- Have you been feeling more tired than usual, lethargic or fatigued despite sleeping a normal amount?
- Are you experiencing a headache?
- Are you feeling less alert than normal?
- Have you received an organ transplantation before?
Self-diagnose with our free Buoy Assistant if you answer yes on any of these questions.
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- Mosquito Bites. MedlinePlus. Medline Plus Link. Published May 16, 2018.
- Prevent Mosquito Bites. Centers for Disease Control and Prevention. CDC Link. Published March 19, 2018.
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- Steen CJ, Carbonaro PA, Schwartz RA. Arthropods in dermatology. J Am Acad Dermatol 2004;50(6):819-42. JAAD Link.
- Castells MC. Insect bites. Feldweg AM and Baron EL, eds. UpToDate. Waltham, MA: UpToDate Inc. UpToDate Link.