Mosquito bites can cause itching and discomfort during warmer weather, and they can also transmit serious diseases, such as Zika, West Nile virus, and many others.

Choosing an effective mosquito repellent can help prevent bites, save individuals from the irritation of a bite, and protect them against mosquito-transmitted illness. With so many mosquito repellents available, it can be tricky to make a good decision.

Surprisingly, not all mosquitoes bite; only female ones do. When a female mosquito bites, she is feeding on the blood of the host, which contains necessary proteins and nutrients for her reproductive purposes.

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Using mosquito repellent is especially important in warmer climates as mosquitoes can carry dangerous diseases, including Zika or malaria.

It is important to know what active ingredients a repellent contains before purchasing it. Although a label or a product’s branding may claim it is capable of great things, it is the active ingredient that determines how effective it will be.

There are a variety of active ingredients commonly used in mosquito repellents. These may be natural or synthetic compounds. Some act as both a repellent and insecticide against mosquitoes.

Considerations to make when weighing up the effectiveness of the active ingredients include:

  • how effective the product is at repelling one or more species of mosquito
  • how long the repellent will work

The following are some of the most common active ingredients used in mosquito repellents.


DEET has been around for more than 60 years. First patented by the United States Army to help protect service men from biting insects, DEET has long proven its effectiveness in repelling all species of mosquito. It also protects against ticks, chiggers, fleas, gnats, and some flies.

DEET can be applied directly to the skin and is available in concentrations ranging from 5-100 percent in more than 100 different products. Its biggest downfall is its greasy feel and disintegrating effects on plastic and polyester.


Permethrin is both a repellent and a contact insecticide. It is not considered safe to apply to human skin. Instead, it is put on clothing, tents, and other gear. In some areas, it has been used to help manage or kill the mosquito populations.


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Understanding the active ingredients in mosquito repellent is key to understanding how effective different brands are.

Picaridin is a newcomer to the U.S., and the World Health Organization (WHO) recommends it for its effectiveness in repelling malaria-carrying mosquitoes. However, it is not as effective with all species of the insects.

Unlike DEET, picaridin is odorless, does not have a greasy feel, and will not destroy clothing or plastics.

It can be obtained in concentrations from 5-20 percent. At 20 percent, it is equivalent to the DEET concentration used by the U.S. military and lasts for 8-10 hours.


There are not as many research studies on IR3535 as on other repellents. However, preliminary studies seem to indicate it is not as effective as DEET or some of the other compounds used for repelling insects. It is considered safe for both clothing and skin applications.


Citronella has been studied several times over the years. While not considered as effective as some other repellents, citronella has shown better repellent capabilities than DEET for some species of insects.

Citronella is considered safe to put on the skin, and most research suggests it should be applied every 30-60 minutes for maximum effectiveness.


This is the synthesized version of the oil of lemon eucalyptus (OLE), which is the only natural substance recognized by the Centers for Disease Control and Prevention (CDC) for repelling mosquitoes that carry the West Nile virus.

A respected study found that PMD repelled mosquitoes as well as DEET in trials lasting 6 hours. However,

Derived from a natural source, PMD is generally considered safe for all to use.

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Looking at the labels is a good way to determine which mosquito repellent will be most effective. If the active ingredients make up a high percentage of the ingredients, it is usually more effective.

The length of time a product is effective in preventing mosquito bites is one of the first things to look for in a repellent. This information appears as a small graphic on the packaging.

Labels on repellents include instructions on how to use the product, precautions, and any dangers. The ingredients are listed, along with their percentages, on the front of the bottle.

The percentage of the active ingredient helps determine how effective it will be and how long it will last. Usually, the higher the percentage, the better and longer the repellent will work.

The inactive ingredients may be important for a person to know, as well, if they are likely to have allergies or reactions to certain ones. These substances do not affect how the product works, but rather help bind it, make it smell better, or preserve it better.

Preventing mosquito bites involves preparation. Often, this requires more than simply picking the right repellent. It can also include knowing when and where mosquitos tend to hunt.

When outdoors, people should wear long sleeves and pants to protect themselves from bites. Repellent should be applied to exposed skin and clothing wherever possible.

Finally, a person should know how regularly to apply a repellent for maximum effectiveness in preventing bites.

Mosquitoes are known worldwide for spreading some deadly diseases. Most people are happy to avoid an itchy bite by using a repellent. But these products can also prevent someone catching a disease carried by a mosquito.

Diseases that are carried by mosquitoes include:

Whether or not a mosquito might carry a certain disease depends mainly on the region of the world where it lives.

For example, malaria is more common in parts of Southeast Asia and Africa than in Europe or North America. Similarly, Zika has broken out in Central and South America, and in parts of North America.

Local centers for disease and insect control have information geared towards the risks in their areas. People concerned about these should seek information from the local agencies.