Mosquitoes: how to prevent them from biting!

It is mosquito season as I sit on my porch watching these mini-vampires hover over me and my laptop. The problem with mosquito bites is:

Transmission of infections:

  • West Nile Virus: last year (2014) there were 1 presumptive viremic blood donor in North Carolina.

  • St. Louis encephalitis (actually most cases have occurred in Texas) is caused by a bite from a virus-infected mosquito and can cause brain inflammation especially in the elderly. In contrast, in Western Equine Encephalitis the viral infection is more severe in infants and young children but can also be spread to horses by infected mosquitoes. There is no vaccine or specific licensed treatment for these infections.

  • In other parts of the world, Dengue fever, Yellow fever and malaria are commonly spread by infected mosquitoes.

Allergic reactions:

  • Most people are sensitized to mosquito saliva from bites during childhood. The usual skin symptoms are hive- like reactions at the site of the bite or papules (bumps) that occur several hours later.

  • Severe generalized (anaphylactic) reactions to mosquito bites are very rare.

  • Skeeter Syndrome is an intense local allergic reaction to the polypeptides in mosquito saliva. Frequently there is associated fever and the misdiagnosis of cellulitis (skin infection) is made and antibiotics unnecessarily prescribed. This reaction is more common in children less than 4 years old.

So, what are our options for preventing mosquitoes from biting us?

The Scientific data on treatments is scarce and most scientific studies have taken place in the laboratory as “arm in the cage” testing rather than in the field as a real life scenario.

Vitamin B1 (Thiamine): 100 mg (1000x the usual daily dose of Vitamin B1) of this water-soluble vitamin once a day can repel mosquitoes from biting for several hours. According to Stewart Harvey, PhD from Salt Lake City, “the repellent effect is attributed to a foul odor, undetected by humans, unless one smells the bottle. Biting insects, which are attracted by carbon dioxide, are repelled. Mosquitoes, deer flies, horse flies, and chiggers are repelled. It is not known whether arachnids are repelled, although deer ticks seem to be.” Some of the advantages are less expensive, does not rub off on clothes, well tolerated and non-oily. Thiamine might not properly enter the body in people who have liver problems or drink a lot of alcohol. An overdose of over 1000 mg of Vitamin B1 could lead to skin rash, allergic reaction, agitation, insomnia, or heart palpitations. The only study I found that showed Vitamin B1 did not work was published in 1969.

DEET (N,N-diethyl-3-methylbenzamide): This compound was developed by the U.S. Army after jungle warfare in WWII. For the past 60 years, this chemical has been effective and with a strong safety record. In an article from the New England Journal of Medicine in 2002, reports “DEET-based repellents remain the gold standard of protection under circumstances in which it is crucial to be protected against arthropod bites that might transmit disease.” The chemical is commonly found in mosquito repellents and the duration of action is directly correlated with the concentration. The higher the concentration, the longer the duration of action. The American Academy of Pediatrics advises against using repellents with DEET concentrations higher than 30% on any child.

DEET + Permethrin: For our U.S. military troops, the Department of Defense Insect Repellent System includes DEET-containing repellant applied directly to the skin and permethrin applied to the battle uniform. This prevents arthropod (insects and spiders) bites. The permethrin last longer when applied to the battle uniforms than onto the skin.

Picaridin: this synthetic compound repels insects, ticks and chiggers. It was first made available in the 1980s. It was made to resemble the natural compound piperine, which is found in the same group of plants that make black pepper. Picaridin has been widely used as an insect repellent in Europe and Australia, but only since 2005, has it been available in the U.S. Picaridin is available as pump spray, wipes, liquids and aerosols. For more information, go to:


  • Oil of Citranella: Some people apply diluted citronella oil directly to their skin to keep mosquitoes and other insects away. The duration of action however is short, about 20 minutes. It is also used in tiny amounts in foods and beverages as a flavoring. In manufacturing, citronella oil is used as a fragrance in cosmetics and soaps. Citronella oil should NOT be eaten in large amounts (a toddler died after swallowing insect repellent containing citronella oil) or inhaled as it could lead to lung damage.

  • Other essential oils: Oils of Lemon Eucalyptus, regular eucalyptus, cinnamon and castor have been used as natural mosquito repellants. There is insufficient data on use in pregnancy, breast feeding and young children and caution must be used as these are potent oils that may irritate the skin and therefore require diluting in products (other than water).

At Family Allergy Asthma & Sinus Care, our goal is to help prevent itching, including itching from bug and mosquito bites. I hope this information helps keep the pesky mosquitoes from dining on you!