Mosquito Bites: Recognizing Bites, Care, and Complications

Medically Reviewed By Deborah Weatherspoon, Ph.D., R.N., CRNA
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Mosquitoes are flying insects that bite people and animals. Mosquito bites are often itchy and irritating, and mild or uncomplicated cases can cause a circular welt, which often resolves after a few days. However, bites can also present serious complications in some cases, such as infection and disease. There are more than 200 different types of mosquitoes that inhabit the United States, with around 12 types that carry diseases that can make people sick. The other types, called nuisance mosquitoes, can be irritating, but their bites usually do not spread disease.

This article explains what happens when a mosquito bites. It also reviews the symptoms, causes, and complications of mosquito bites, as well as treatment and prevention.

What happens if you have a mosquito bite?

An adult male stands outside in shorts with no top, spraying aerosol insect repellant over his bare skin.
Cinema Tigers/Stocksy United

Only female mosquitoes bite humans and animals. This is because they need sustenance to produce eggs.  

Mosquitoes commonly live near the water sources where they lay their eggs. When female mosquitoes bite, they inject their proboscis, their mouthpart, into your skin. This is usually painless, so often we are not aware when mosquitoes bite.

When a mosquito bites, they draw blood from you for food and inject saliva into your skin. Their saliva contains chemicals that reduce blood clotting and make the blood vessels wider to make it easier for blood to flow through the bite.

Our immune systems react to the protein in the mosquitoes’ saliva, causing the hallmark itching and swelling of mosquito bites. Redness can also occur on some skin tones.

Mosquito bite reactions vary. People more likely to experience more severe reactions include:

What do mosquito bites look like?

After a mosquito bites, and often within minutes, you may notice an itchy, inflamed pale or flushed patch of skin, known as a weal, with a very small puncture wound in the middle.

The swollen area might be irregularly shaped instead of perfectly circular.

Additionally, you may find multiple bites in one area, most often on patches of exposed skin.

Additional signs and symptoms of a mosquito bite can include:

  • a hard circular bump that itches, with a flushed or pale color
  • a bump that appears around a day after the bite
  • small blisters instead of bumps
  • dark spots that resemble bruises

In addition, infected bites may present pus, warm skin, and extensive redness around the bite.

How do I know whether something is a mosquito bite?

Unless you watched a mosquito land on your skin or know that there are many mosquitoes around, it is sometimes difficult to determine whether your symptoms are definitely from a mosquito bite.

Generally, mosquito bites do not hurt but instead itch, while bites and stings from bees, spiders, ants, wasps, or hornets can be quite painful as well as itchy.

Some insect bites can have distinctive characteristics that may help to differentiate between them. For example, ticks usually bite in hidden areas behind the ears, in the groin, or in the armpits, and their bites sometimes cause a large, circular bull’s-eye rash, which is a sign of tick-borne illness.

Pictures

Below are some examples of the appearance of mosquito bites.

hg-mosquito-bite-closeup-resized.jpg

This image shows a mosquito bite with a swollen weal at the bite site.

This image shows a mosquito bite with a swollen weal at the bite site.

Azhari Fotolestari/Shutterstock

mosquito-bite-scaled.jpg

A mosquito bite causes a swollen, flushed weal.

A mosquito bite causes a swollen, flushed weal.

Image credit: ProjectManhattan, 2013.

hg-mosquito-bite-streak-resized.jpg

Insect bites, including mosquito bites, can cause infection. In some cases, they may present a red streak from the affected area.

Insect bites, including mosquito bites, can cause infection. In some cases, they may present a red streak from the affected area.

Erythematous patch with central bulla on the ventral forearm, with a lymphangitic streak extending to the antecubital fossa in a patient with herpes simplex virus infection versus a reaction to an arthropod bite. (Photograph obtained by authors at New York University Langone Medical Center in January 2015.)

Related conditions and complications

For most of us, mosquito bites are an annoyance. However, mosquito bites also can carry serious risks and complications. These complications can include:

  • allergic reaction
  • inflammatory reactions, such as skeeter syndrome
  • infection from scratching
  • infection due to the transmission of disease from the mosquito

Mosquito-borne diseases

Mosquitoes can transmit several different diseases to people and animals when they bite. They can transmit these diseases through viruses, bacteria, or parasites.

While mosquitoes can carry many diseases, such as yellow fever, the most frequent mosquito-borne diseases in the U.S. include:

  • West Nile virus
  • dengue
  • chikungunya
  • Zika

Malaria is also a common mosquito-borne disease. It was particularly common in the U.S. in the 20th century and earlier.

When to seek help

Often, mosquito bites resolve in a few days.

However, if symptoms get worse or new symptoms appear, it is important to get medical help, as this may indicate infection or further complication.

Seek urgent medical help for symptoms of complications or severe reactions. These symptoms can include:

  • hives
  • fever
  • swollen lymph nodes
  • a red or flushed streak on the skin of the limbs or near the bitten area
  • symptoms of anaphylaxis, such as difficulty breathing, swelling, and nausea

Rarely, people may experience a severe allergic reaction to a mosquito bite, called anaphylaxis. This is a life threatening situation that requires immediate medical attention.

Learn more about anaphylaxis, including its symptoms, here.

First aid

First aid may help you deal with your symptoms and alleviate irritation.

Methods of first aid for mosquito bites can include:

  • washing your bites with soap and water to help prevent infection
  • applying an ice pack wrapped in a cloth to the affected area for no more than 10 minutes at a time
  • avoiding scratching the bites
  • contacting your doctor concerning any debilitating symptoms or symptoms that do not improve after a few days
  • calling 911 or seeking emergency care for any severe symptoms following a bite that indicate a serious complication

Treating mosquito bites

Most mosquito bites will resolve on their own and will not need clinical treatment.

If you experience symptoms of a more severe reaction, contact your doctor or seek emergency medical treatment.

Home remedies

In addition to first-aid care, you can try a few home remedies to help reduce any irritation:

  • Baking soda paste: Mix 1 tablespoon of baking soda with drops of water until a thick paste forms. Apply this to the bite for 10 minutes, and then wash it off.
  • Oatmeal paste: Form a paste with oatmeal oats and water and apply to the bite area.
  • Over-the-counter (OTC) relief: Discuss OTC options with your pharmacist. Anti-itch and antihistamine options are available to reduce irritation and swelling.

Prevention

You can prevent mosquito bites and complications from them in several ways:

  • Covering the skin: Cover any exposed skin with clothing. However, mosquitoes can sometimes bite through thin fabric, so spray your clothes with insect repellant.
  • Using insect repellant when you are outside: The Environmental Protection Agency (EPA) tests and certifies insect repellants for safety and efficacy. Effective options often have ingredients including DEET, picaridin, IR 3535, oil of lemon, or eucalyptus.
  • Avoiding mosquitoes in the home: Use air conditioning or fix your screens to prevent mosquitoes from entering your home.
  • Removing mosquito-breeding areas: Mosquitoes often live near calm, untreated water.
  • Planning before travel: In advance of any trips, make sure to research whether you need extra protection against mosquito-borne illness during your trip. Contact your doctor about vaccines you might need in certain countries to prevent disease.  

Other frequently asked questions

Below are some commonly asked questions about mosquito bites.

How long does it take for mosquito bites to go away?

Most mosquito bites often take just a few days to go away.

You can aid healing by avoiding scratching, which can cause complications such as infection.

How do I stop a mosquito bite from itching?

You can try home remedies and OTC products to help reduce itching.

These options may include applying an ice pack for 10 minutes, applying an anti-itch ointment, or taking an oral antihistamine.

Why do my mosquito bites get huge?

If you have a more severe reaction to mosquito bites, your bites might be larger or more swollen.

This can happen if you have not been bitten by a certain species of mosquito before. It can also happen to younger children and people with immune disorders.

How many mosquito bites can you get before they become dangerous?

Generally, the effects of mosquito bites do not increase or accumulate as you get more bites.

However, even one mosquito bite is dangerous if the mosquito happens to carry a virus or if a person is severely allergic to mosquitoes.

Additionally, it is possible that the more bites you obtain, the more likely it is that you will experience a bite from a mosquito that may transmit disease.

Summary

Mosquito bites occur when female mosquitoes bite the skin and take blood, causing itchiness, swelling, and sometimes other symptoms.

While bites can often resolve without needing treatment, sometimes within a few days, mosquito bites can also present complications and risk of further adverse health effects.

Complications can include transmission of disease, infection, and allergic reaction. Seek urgent medical treatment for any severe symptoms following a bite, such as a fever, difficulty breathing, or a flushed stripe on the skin.

Bites without complications are manageable without clinical treatment. Self-care methods such as applying an ice pack or an ointment may help to relieve irritation.

Prevention methods such as using insect repellant and researching any relevant vaccines before travel are important to avoid bites, irritation, and possible complications.

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Medical Reviewer: Deborah Weatherspoon, Ph.D., R.N., CRNA
Last Review Date: 2022 May 31
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