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Symptoms and Signs of Allergy: Insect Sting

Doctor's Notes on Allergy: Insect Sting

Insect stings to which some individuals are allergic include bees, hornets, wasps, yellow jackets and fire ants. Allergic individuals may develop signs and symptoms that range from mild to severe; mild symptoms may include itching, pain and swelling beyond the area of the sting; it may slowly increase over the next few hours. Severe allergic reactions are a medical emergency – call 911; signs and symptoms include a rapid occurrence, sometimes within minutes, of hives and/or swelling in major body parts like the face, head, neck, arms, hands, legs, or feet. Nausea, vomiting or diarrhea may occur. Difficulty breathing, dizziness and/or fainting, chest pain and tachycardia with a low blood pressure suggests the patient is in anaphylactic shock; if it continues, the patient can die.

The cause of allergic reactions to insect stings is an over reaction of the body’s response to the stinger or venom (most likely a protein component) it interprets as a foreign substance. Part of the allergic response is the release of histamine that helps mediate the body’s response to foreign substances; too much can participate in producing an anaphylactic reaction (shock).

Medical Author:
Medically Reviewed on 3/11/2019

Allergy: Insect Sting Symptoms

Most insect stings cause some pain and swelling in the area of the sting, called a local reaction.

  • People who are allergic to bee stings or who have been stung many times may react more dramatically.
  • A severe local reaction may lead to pain and swelling that increase over the next few hours and becoming very uncomfortable. This does not constitute an anaphylactic reaction. The reaction must involve at least 2 of your body's organ systems (such as lungs and heart) to qualify as an anaphylactic reaction.
  • Although most local reactions are not serious, if they are near the face or neck, swelling can quickly block the airway and cause serious problems.

Fire ant stings

  • Fire ant stings cause a reaction in almost everyone.
  • Itchy hives usually form at the site immediately and recede within an hour.
  • A small blister forms at each site within 4 hours.
  • Within 8-24 hours, a small sore with pus forms at each sting site. The area around the sores may feel burning and itchy. The pus does not mean the sore is infected.
  • The sores rupture within 72 hours. The itching, pain, and redness may last for several days but should improve gradually.
  • Worsening redness, pain, swelling, and warmth may signal an infection at the site. If this occurs, see your health care provider right away.

Symptoms over the entire body are always a concern because they may signal an anaphylactic reaction. If these reactions progress, they may lead to death, sometimes within a matter of minutes. These reactions may include the following:

The dizziness and fainting are due to a dangerously low blood pressure. This condition is known as "shock," and anaphylaxis is often called anaphylactic shock.

Allergy: Insect Sting Causes

An allergic reaction occurs when the immune system of the body overreacts to an "invader" such as insect venom (the allergen). This overreaction is sometimes referred to as a hypersensitivity reaction.

The white blood cells produce an antibody to the protein in the venom.

  • The allergic reaction occurs when the antibody, known as immunoglobulin E, or IgE, comes in contact with the protein, either at the first sting or later.
  • IgE promotes release from certain cells of chemicals and hormones called "mediators." Histamine is an example of a mediator.
  • It is the effects of these mediators on organs and other cells that cause the symptoms of the allergic reaction.

Ants, bees, and wasps have a stinger or venom sac and gland on their tail that they use to inject venom.

  • Several stings may occur, particularly if you accidentally disturb a hive or nest.
  • This is particularly true with fire ants and so-called Africanized bees.
  • Africanized bees are the result of breeding of domesticated and wild honeybees in Africa that resulted in a very aggressive honeybee. The venom of these bees is no more potent than that of normal honeybees, but their aggressive nature increases the likelihood that they will swarm and sting you many times, sometimes hundreds of times.
  • Such a large number of stings may result in serious reactions or death, even if you are not allergic to bee venom.
  • If you are allergic to the venom, then you may have an allergic reaction from even a single sting. This is called an anaphylactic reaction. It can be dangerous, even life threatening.

An anaphylactic reaction does not usually occur on the first sting.

  • The immune system makes the antibody at the first sting and stores it on special cells until the next sting. This is called "sensitization."
  • At the first sting, therefore, the body does not have antibodies specific to the venom.
  • Only on a second or later sting can the body mount a major defense against the venom.
  • This is when a life-threatening anaphylactic reaction may occur.
  • Anaphylactic reactions are rare, and do not happen to every person who is stung by an insect.
  • When an anaphylactic reaction seems to occur on the very first sting, probably the person was stung before without realizing it.

Insect venom is used to treat certain medical conditions.

  • In Chinese herbal medicine, the venoms of various insects in this class are used either as direct stings (as a treatment for arthritis and other chronic diseases) or are applied to the skin or the eyes.
  • Such apiotherapy (the medicinal use of honeybee products) may result in an anaphylactic reaction in people who are allergic.
  • Allergy shots given by an allergy specialist also contain venom but are specifically designed to be given to allergic people to reduce their sensitivity to the allergen.

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Kasper, D.L., et al., eds. Harrison's Principles of Internal Medicine, 19th Ed. United States: McGraw-Hill Education, 2015.