Mosquito Bites

Medically Reviewed by Poonam Sachdev on November 02, 2023
10 min read

Mosquitoes are small, flying insects that are common to the U.S. They have a long, needle-like mouth part called a proboscis that breaks skin and sucks blood from people and animals.

Some mosquitoes are considered to be vectors, or insects that spread germs to people and animals that can cause illnesses. A mosquito can become infected with a disease after taking blood from an infected person or animal, and just a few mosquitoes can carry an illness throughout a community.

They live in many places, such as forests, marshes, and tall grass areas, but can live indoors, too. They are attracted to standing water because that’s where they lay their eggs. Young mosquitoes live in water until they become adults.

Adult mosquitoes can live for about 2 to 4 weeks depending on their type and environmental factors, such as temperature and humidity. Most mosquitoes hibernate or die when the temperature drops below 50 degrees.



There are more than 3,700 types of mosquitoes in the world and 200 in the U.S. Of the 200 types, about 12 spread germs that can cause illnesses in people. 

Some mosquitoes are known as nuisance mosquitoes. They can bite but don't spread germs. Most of the mosquito types in the U.S. are nuisance mosquitoes. They are usually more of a problem after heavy rains or natural disasters like floods and hurricanes.

 A mosquito bite is a red, itchy, raised bump you get when a mosquito bites your skin and its saliva gets into your blood. The saliva from a mosquito triggers a mild allergic reaction that causes the area of the bite to become red, itchy, and swollen.

Most people have had mosquito bites at some time in their life. Usually, you swat a mosquito away and cope with the unpleasant but temporary itch. But because you can't tell which mosquitoes can spread germs, it's important to protect yourself from these bites.

Why do mosquitoes bite?

Female mosquitoes bite because they need the protein from blood to produce eggs. Males don't bite. You might be more likely to get mosquito bites depending on warm temperatures, light, body odor, and sweat. 

When a mosquito bites, you might feel a quick sting, or you may not feel it at all at first. 

The main symptom of a mosquito bite is a puffy, red bump that appears a few hours or days after you've been bitten. You might notice the bump becomes hard and itchy after a day or so.

Mosquito bites can look different on different people. If you’ve had multiple bites, you can have many bumps. Bumps could be a different color than your skin or, instead of bumps, you might have small blisters or dark colored spots. 

If you have very big and uncomfortable mosquito bites and home remedies don’t work, call your doctor. Prescription treatments may help relieve the itch and swelling.

Why do mosquito bites itch?

When a mosquito bites you, its saliva goes into your blood and can cause a mild inflammatory reaction. Your immune system releases histamine in response to the bite, and that can cause itching and swelling in the area of the bite.

Skeeter syndrome (mosquito bite allergy)

Most people have a mild reaction to mosquito bites. Severe allergic reactions to mosquito bites, or skeeter syndrome, are rare but can happen. Skeeter syndrome can happen at any age, but it most commonly happens in children because their immune systems are still developing. 

Symptoms of a reaction can include developing large hivesblisters, large areas of swelling, skin warmth, fever, or swollen lymph nodes. Talk to your doctor if you have any of these symptoms. Symptoms often go away in 3-10 days. 

In extremely rare cases, mosquito bites can cause anaphylaxis, which is a medical emergency that can lead to difficulty breathing and a drop in blood pressure. Get help immediately if you have any of these symptoms following a mosquito bite. 

Mosquito bite infection

If you scratch a mosquito bite, it can become infected. One sign that a bite is infected is redness around the bite, especially if you notice the redness spreading. An infected bite might also feel warm to the touch.

The infection, also known as cellulitis, happens when bacteria from your hands get into the area of the mosquito bite. Other signs of an infection include:

  • Swollen lymph nodes
  • Chills or fever above 100 degrees Fahrenheit
  • Pus or leaking fluid
  • Area of the bite is warm to the touch
  • Red streaks outside of the bite

It's important to see your doctor if you have symptoms of an infection. Once cellulitis is confirmed, your doctor will likely prescribe an antibiotic to get rid of the bacteria.


It’s tough advice, but leave the mosquito bite alone. When you scratch, it creates openings in your skin that let bacteria in and cause infection.

If the symptoms from the mosquito bite aren't changing or getting worse, there are a few home remedies you can try to relieve the itch and lower your chances of an infection:

  • Wash the area with soap and water.
  • Apply calamine lotion or anti-itch cream.
  • Put an ice pack on the bite.
  • Take an over-the-counter antihistamine.
  • Raise the area of the bite to reduce and prevent swelling.
  • If a bite causes fever, vomiting, or shortness of breath, call 911 or go to an emergency room immediately.

Many natural and home remedies are commonly recommended as ways to stop the sting and itch of a mosquito bite. To relieve symptoms, you may want to use:

  • Baking soda. Mix a tablespoon of baking soda and a bit of water to make an itch-relieving paste. Gently apply to the bite. Wait 10 minutes, then rinse.
  • Oatmeal. When it comes to oatmeal for mosquito bites, don’t grab what’s in your kitchen. You want to look for colloidal oatmeal creams or bath treatments, available at most stores and pharmacies. Colloidal oatmeal binds to your skin, locking in moisture. It’s used to treat itchy conditions like eczema and psoriasis and could help soothe a bug bite, too.
  • Basil. This fragrant herb pulls double duty when it comes to battling mosquitoes. Plant it and it keeps mosquitos away. Crush it and rub it gently on your skin, and some research suggests it soothes the itch of a mosquito bite.
  • Aloe vera. The gooey, clear gel found inside an aloe vera plant has been used for more than 6,000 years to treat many ailments. It’s proven to be a helpful remedy for burns and itchy skin due to psoriasis.
  • Chamomile. This herb, often found in teas, is used to relieve anxiety and insomnia. Some say applying it to the skin can help soothe skin rashes and irritations, but there’s not enough information to say it works. If you’re allergic to ragweed, you may have a reaction to chamomile, too.
  • Menthol. Menthol products cool the skin, which can temporarily relieve the itch. Rubbing a bit on a mosquito bite might briefly stop the desire to scratch. You’ll find menthol in a variety of drug store liquids, skin creams, and ointments.
  • Honey. Honey contains an enzyme that calms inflammation. Applying a small amount of honey to the bite might relieve some of the itching and swelling.

Most mosquitos are only annoying, but some types can spread certain diseases, including West Nile and Zika. If a mosquito bites an animal or human that has a certain disease, the infected blood goes into the mosquito’s body. The infected mosquito can then spread that disease to the next animal or human it bites through its saliva. If an infected mosquito bites you and you become sick, you have a mosquito-borne disease.

West Nile virus

Most people who get West Nile virus don't have symptoms. About 1 in 5 will have a fever and other flu-like symptoms. Feeling worn out could take months to go away completely. A few people get a more serious infection that causes brain swelling, or meningitis. There's a very small chance you could die.

People in 48 of the 50 U.S. states, Africa, Europe, the Middle East, and West and Central Asia have had West Nile.


Mosquitoes can pass along viruses that cause encephalitis, which is inflammation around your brain and spinal cord (The brain swelling with a serious West Nile infection is a kind of encephalitis).

Symptoms usually come on suddenly and can include headache, fever, dizziness, upset stomach, and overall tiredness.

You location can determine the type of  encephalitis you can get, including:

  • La Crosse encephalitis -- mostly in the upper Midwestern, mid-Atlantic, and Southeastern states of the U.S.
  • St. Louis encephalitis -- throughout the U.S., especially Florida and Gulf of Mexico states
  • Eastern Equine encephalitis -- Atlantic, Gulf Coast, and Great Lakes states; the Caribbean; Central and South America
  • Japanese encephalitis -- Asia and the Western Pacific

There is no effective antiviral medication for encephalitis from mosquito bites, and a treatment plan can depend on your overall health, age, and degree of sickness.

You'll need emergency care right away for serious symptoms, such as confusion, seizures, and muscle weakness to prevent brain damage and other complications. You can get shots to prevent Japanese encephalitis before you travel to the area.

Zika virus

Discovered in Africa in the 1940s, this virus has spread to South and Central America, Mexico, the Caribbean, Southeast Asia, and the Pacific Islands.

Most people don't know they have Zika. The symptoms are mild and usually go away in less than a week. You may have a fever, joint or muscle pain, pinkeye, or a rash. The virus has been linked to Guillain-Barre syndrome and a birth defect called microcephaly.

  • Guillain-Barre is a nervous system disorder that can cause weakness and paralysis. Most people recover.
  • Microcephaly causes a baby's head to be small and not fully develop. Babies with this condition may have developmental and intellectual delays and other problems.

There's no vaccine to prevent the Zika virus. The CDC recommends pregnant women not travel to areas with ongoing Zika infections.

Chikungunya virus

Found mostly in the Caribbean and South America, chikungunya has been spreading in the U.S. It causes serious joint pain that may last several weeks. You'll need rest and fluids until symptoms go away. Your doctor may suggest pain relief medicine, too.

Dengue fever

With dengue fever, you'll likely get a sudden high fever and may bleed a little from your nose or gums. It can be very uncomfortable. Rest and treating the symptoms are the only things you can do for dengue.

Some people get a more severe form, known as dengue hemorrhagic fever. If your small blood vessels become leaky and fluid starts to build up in your belly and lungs, you'll need medical care right away.

Usually people in the U.S. with dengue bring it back with them from warm parts of Africa, Asia, the Pacific Islands, Central and South America, and the Caribbean -- especially Puerto Rico. In the last 20 years, though, there have been outbreaks in South Texas, Hawaii, and the Florida Keys.

Yellow fever

You're not likely to catch yellow fever because most countries in tropical areas of Africa and the Americas require travelers to get the vaccine for it. Most people who get yellow fever won't notice anything, but some may feel like they have a mild case of the flu. If you get symptoms, rest, fluids, and medication can help, although you could feel weak and tired for several months.

Some people who have mild symptoms develop severe symptoms after they start feeling better, which could cause death. Serious symptoms include a high fever, yellowing of the skin and whites of the eyes (jaundice), bleeding, and liver and kidney failure.


No one has gotten sick with malaria in the U.S. since the early 1950s. But this oldest mosquito-borne disease recently caused 619,000 deaths worldwide, with a 10% increase happening during the pandemic due to delays in needed malaria services. Countries around the equator in Africa and tropical islands in the Pacific, such as Papua New Guinea, have the most cases of malaria.

You can take drugs to help prevent malaria when you travel. Researchers are working on a vaccine.

When should I be worried about mosquito bites?

If you have a mosquito bite and other symptoms such as a high fever, body aches, headache, or sign of infection, contact your doctor.

In the U.S., mosquito season begins in early spring, peaks in the summer, and ends with the first freeze. In parts of the world with warmer weather, they may be active year-round.

To prevent mosquito bites and the illnesses they spread:

  • Wear light-colored clothing that's thick and provides full-coverage.
  • Don't travel to areas with infections.
  • When traveling, make sure vaccinations are updated and take medication to prevent infection.
  • Keep grass and plants around your home trimmed and gutters clean.
  • Get rid of places that water can collect around your home.
  • Stay away from standing water -- where mosquitoes breed.
  • Keep water in pools and landscaping moving.
  • Use screens on your windows or a mosquito net when sleeping outdoors.
  • Stay indoors at dusk and dawn, when mosquitoes are most active.
  • Put mosquito repellent on your bare skin.

Mosquito repellent

When choosing a mosquito repellent, look for a product with one of the following EPA-approved active ingredients:

  • DEET. N,N-diethyl-meta-toluamide, or DEET, is the most common and effective repellent against mosquitoes. It works by interrupting a mosquito’s ability to detect carbon monoxide and body odor, so the mosquito can’t detect you.
  • Picaridin. Picaridin is a newer repellent. It works like DEET by preventing mosquitoes from detecting you. 
  • Oil of lemon eucalyptus. Oil of lemon eucalyptus, or PMD, is repellent made of oil from the leaves of the lemon eucalyptus tree. It is not recommended for children under 3 years old.