Have you ever noticed that mosquitoes seem to bite some people more than others, even when everyone is in the same place at the same time, with the same amount of exposed skin?

Because mosquitoes can spread diseases like malaria, Zika, and dengue fever, scientists have been investigating the various factors that may make some people more attractive to mosquitoes. One of these factors is blood type.

In this article, we examine the link between mosquito bites and blood type, and also look at other factors that attract mosquitoes.

People with different blood types have different sets of specific proteins (antigens) on the surface of their red blood cells. You inherit your blood type from your parents. There are four different blood types:

  • A: only A antigen on the surface of red blood cells
  • B: only B antigen on the surface of red blood cells
  • AB: both A and B antigen on the surface of red blood cells
  • O: no A or B antigen on the surface of red blood cells

Some people can also have these antigens in body fluids like saliva or tears. These people are called secretors. For example, someone with blood type A would be a type A secretor. Those with blood type O secrete H antigen, a precursor to A and B antigen.

So, what does all of this mean for how attractive you are to mosquitoes?

Generally speaking, mosquitoes appear to be more attracted to people with blood type O than other blood types. Below, we’ll take a deeper dive into the research on this topic.

An older study from 1974 recruited 102 participants to look into various individual factors that could attract mosquitoes. When the researchers analyzed the results, they found that mosquitoes preferentially fed on people with blood type O.

Recently, a 2019 study also assessed blood type preference in mosquitoes. They did this by providing samples of different blood types in separate feeders. It was observed that mosquitoes preferred to feed from the type O feeder than the other feeders.

A 2004 study examined mosquito preference for blood type as well as secretor status. The overall results found that:

  • More mosquitoes landed on people with blood type O. However, this result was only statistically significant when compared with blood type A and not to the other blood types.
  • Mosquitoes landed on type O secretors significantly more often than type A secretors.
  • When blood type antigens were applied to the arms of study participants, mosquitoes were significantly more attracted to people with H (type O) antigen than A antigen. Meanwhile, A antigen was significantly more attractive than B antigen.

Since blood type antigens can be found in the saliva and tears of secretors, it may be possible that mosquitoes can sense these antigens as they approach a person. However, there hasn’t been any research done to support this idea yet.

Also, remember that while the 2004 study found a preference for blood type O over type A, the same can’t be said for the other blood types. Clearly, other individual factors can influence who mosquitoes choose to bite.

Summary

The available research indicates that mosquitoes may prefer individuals with blood type O. However, it’s likely that many other additional factors also play a role in a person’s attractiveness to mosquitoes.

Let’s take a closer look at some of the other individual factors that can attract mosquitoes.

Carbon dioxide

You release carbon dioxide when you exhale, leaving a trail of carbon dioxide that a mosquito can follow.

An increase in carbon dioxide in the air can alert a mosquito that a possible host is close by. The mosquito will then move toward the source of the carbon dioxide.

Body odor

If you find that mosquitoes bite you more than other people, you may just smell extra good to them. Several factors may influence what you smell like to a mosquito, such as:

  • Compounds on your skin. Researchers have found several compounds present on the skin that make some people more attractive to mosquitoes. Examples include ammonia and lactic acid.
  • Bacteria. The bacteria on your skin can also affect your body odor. According to a 2011 study, people with a higher abundance but lower diversity of bacteria on their skin were more attractive to mosquitoes.
  • Genetics. It’s been found that mosquitoes are more attracted to odors on the hands of identical twins than those of fraternal (nonidentical) twins.

Heat

In addition to carbon dioxide and odors, our bodies also give off heat. Research from 2017 has found that female mosquitoes will move toward heat sources, regardless of their size.

Color

Although it’s not clear why, research from 2018 has shown that mosquitoes are more attracted to black objects. Because of this, you may notice that you get more mosquito bites if you’re wearing darker colors.

Alcohol

A small 2002 study found that mosquitoes may be more attracted to people who’ve been drinking.

In the study, mosquitoes landed on participants more frequently after they’d consumed a small amount of beer.

Pregnancy

One 2004 study found that a higher number of mosquitoes were attracted to pregnant women when compared with nonpregnant women.

This may be because pregnant women release more carbon dioxide and have a higher body temperature.

Mosquito repellents that are approved as safe and effective by the Environmental Protection Agency (EPA) include the following active ingredients:

  • DEET (marketed as Repel, Off! Deep Woods, and other brands)
  • picaridin (marketed as Natrapel and Sawyer)
  • 2-undecanone (this repellent is found naturally in cloves and is marketed as Bite Blocker BioUD)
  • IR3535 (marketed by Merck)
  • oil of lemon eucalyptus (OLE)

Studies from 2015 and 2017 comparing different commercially available mosquito repellents have found that those containing DEET were overall the most effective at deterring mosquitoes.

In addition to the repellents above, some natural products may also repel mosquitoes. Some examples include but aren’t limited to:

Safety tips for using mosquito repellents

  • Always follow the application directions on the product label.
  • Some repellents shouldn’t be used on children under a certain age. Don’t use DEET on infants under 2 months old. Avoid using OLE on children under 3 years old.
  • Try to avoid getting the repellent near your eyes or mouth.
  • Only apply repellent to exposed skin and not under clothing.
  • Keep repellents away from any cuts, burns, or rashes.
  • When you go back inside, wash the repellent off your skin with soap and warm water.
Healthline

In addition to using a mosquito repellent, you can also take the following steps to help prevent getting bitten:

  • Avoid active times. Mosquitoes are most active at dawn and dusk. Try to avoid outdoor activities during this time.
  • Avoid dark clothing. Try to wear light-colored clothing that covers your arms and legs. Clothes can also be treated with a repellent called permethrin.
  • Prevent entry. Check to make sure there aren’t any tears on your window and door screens so that mosquitoes can’t get into your house.
  • Use mosquito netting. If you’re going to be sleeping outside or in a place where mosquitoes can get indoors, consider using mosquito netting.
  • Eliminate standing water. Mosquitos need standing water to reproduce. Try to limit standing water by draining it from things like empty flowerpots and wading pools.

Mosquito bites typically resolve on their own after several days. However, there are some things you can do in the meantime to help ease any itching or discomfort:

  • Apply a cold compress. Gently placing a cool compress or ice pack over the bite for a few minutes may help relieve itching and swelling.
  • Try a baking soda paste. To help alleviate itching, mix 1 tablespoon of baking soda with water to make a paste and apply it to the mosquito bite.
  • Use over-the-counter (OTC) products: Various OTC anti-itch creams and oral antihistamines are formulated to ease itching.

Although it can be very tempting, resist the urge to scratch a mosquito bite. Doing so can increase the risk of a skin infection.

Female mosquitoes suck blood from humans and other animals to help them reproduce. Although mostly annoying, in some parts of the world a mosquito bite can lead to illnesses like malaria.

Research has found that mosquitoes may prefer to bite people with type O blood. However, additional research is needed to further determine the link between blood type and mosquito attraction.

In addition to blood type, other factors like carbon dioxide, body odor, heat, and dark clothing can also attract mosquitoes.

You can reduce your risk of mosquito bites by using mosquito repellents, avoiding outdoor activities when mosquitoes are most active, and eliminating standing water in your yard.