Mosquito Bite Reactions

The onset of summer brings with it the menace of mosquitoes.  Though we are more concerned about diseases transmitted by mosquitoes such as malaria, encephalitis, dengue fever, chikungunya, West Nile virus, yellow fever, filariasis (elephantiasis), Western equine encephalitis, Eastern equine encephalitis, Japanese encephalitis, Venezuelan equine encephalitis, St. Louis encephalitis, La Crosse encephalitis, Ross River fever, Rift Valley fever, and most recently Zika virus-related illnesses, adverse reactions to mosquito bites can be very severe in susceptible individuals.

Mosquitoes inject their saliva into the tiny blood vessels in our skin, before sucking the blood. Immunological reactions to the chemicals in the saliva of the mosquito are usually responsible for the untoward reactions.  The chemicals can also interfere with the clotting mechanism in individuals resulting in local bleeding.

Three types of reactions can occur:

  1. The most common manifestation is localized redness, swelling, and/or itching. The symptoms usually begin a few hours after the bite and usually resolve spontaneously within a few days.
  2. Blistering lesions and/or larger hives (i.e., papular urticaria), sometimes accompanied by mild fever and joint stiffness and pain, may occur and are generally more bothersome than the localized redness, swelling, and/or itching mentioned above.
  3. Very rarely mosquito bites may result in serious generalized reactions (i.e., anaphylaxis), affecting multiple organ systems.

The typical clinical course of sensitization and natural desensitization usually proceeds in five stages:

  1. People who have never been exposed to a particular species of mosquito do not develop reactions to the initial bites from such mosquitoes.
  2. Subsequent bites result in the appearance of delayed local skin reactions.
  3. After repeated bites, immediate wheals may develop.
  4. With further exposure, the delayed local reactions wane and eventually disappear, although the immediate reactions persist.
  5. People who are repeatedly exposed to bites from the same species of mosquito eventually also lose their immediate reactions.


  1. Application of ice and elevating the affected area can help reduce swelling and/or pain.
  2. Blisters need to be cleaned with soap and water.
  3. 1% hydrocortisone cream or ointment which can be found over-the-counter will help control inflammation. This cream or ointment may be applied twice a day for up to 1 week, as there are potential side effects of prolonged use of such steroid creams/ointments.
  4. Oral antihistamines may help relieve itching to some extent.
  5. Antibacterial medications may need to be used if the area becomes infected which is not very common.
  6. In the case of systemic reactions, carrying an epinephrine auto-injector (i.e., EpiPen, Auvi-Q, Adrenaclick) is highly recommended.


  1. Mosquitoes usually breed in pools of standing water. Keeping outdoor areas free of standing water will discourage mosquito breeding.
  2. Mosquito bites occur more often from dusk to dawn. Staying indoors also is advantageous to reduce one’s exposure to mosquitoes.  Using screened windows and screened porches are helpful in reducing mosquito exposure.
  3. Wear protective clothing with long sleeves and pants. Avoid bright colors and heavy perfumes and colognes which can attract mosquitoes.
  4. Insect repellants containing DEET (i.e., N,N-diethyl-3-methyl-benzamide or N,N- diethyl-meta-toluamide) as the active ingredient are most effective. Repellants containing 10 to 25% DEET provide approximately 2 to 6 hours of protection.
  5. Some individuals can be sensitive to DEET, which may cause irritant reactions (e.g., skin rashes, itchy skin, redness of the eyes, watery eyes). Testing the insect repellant on a small area of skin before application over extensive areas is helpful in determining if it is an irritant to a particular individual.  Utilizing only the lowest effective concentration is preferable.
  6. Products containing the active ingredients picaridin, oil of lemon eucalyptus, and IR 3535 (i.e., 3-[N-Butyl-N- acetyl]-aminopropionic acid, ethyl ester or Ethyl 3-[acetyl(butyl)amino]propanoate) are also effective repellants in individuals that do not want to use DEET or react to DEET.

The board certified allergists of Black & Kletz Allergy have had over 50 years of experience dealing with mosquito bite reactions.  Black & Kletz Allergy has 3 office locations in the greater Washington, DC, Northern Virginia, and Maryland metropolitan area.  The allergy doctors at Black & Kletz Allergy diagnose and treat both adults and children with allergies (e.g., hay fever, food allergies, medication allergies), asthma, hives, swelling episodes, eczema, contact dermatitis, insect bites, bee sting allergies, sinus disease, and immunologic problems.  We have offices in Washington, DC, McLean, VA (Tysons Corner, VA), and Manassas, VA and have on-site parking at each location.  The Washington, DC and McLean, VA offices are Metro accessible and there is a free shuttle that runs between our McLean, VA office and the Spring Hill metro    station on the silver line.  Please call us to make an appointment or alternatively, you can click Request an Appointment and we will respond within 24 hours by the next business day.  Black & Kletz Allergy has been striving to provide high quality allergy and asthma care to the residents of the Washington, DC metro area for more than a half a century and we are dedicated to continue delivering state of the art allergy and asthma care in the future.