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Hornet sting
Other Resources UpToDate PubMed

Hornet sting

Contributors: Robert Norris MD, Joanne Feldman MD, MS
Other Resources UpToDate PubMed


Hornets (Vespa species) are large wasps that are related to yellow jackets (Vespula and Dolichovespula species) and paper wasps (Polistes species). They are social insects native to the northern temperate zone of the Eastern Hemisphere, except for one European species (Vespa crabro) that was introduced into the United States in the early 1800s and is now established, though uncommon, in eastern North America.

Wasp stings are the most common human envenomation. The stings from all species are similar, but hypersensitivity reactions may be quite specific. Hornets can sting repeatedly, especially when trapped in clothing, because their stingers do not have barbs like some bees.

Hornet venom is similar to bee venom, but the venoms are generally not cross-reactive. Hornet venom contains enzymes, small peptides, and amines. The allergens include the phospholipases, hyaluronidases, and cholinesterases. Some peptides cause histamine release by degranulating mast cells. Histamine, serotonin, and acetylcholine contribute to the pain associated with hornet stings.

Hornet sting toxicity varies greatly by hornet species. The European hornet sting is less toxic than a bee sting but may be fatal in a sensitized individual or with multiple stings (several hundred). Non-European hornet stings are more toxic than other wasps or bee stings and, in fact, the Asian giant hornet is the most venomous known insect (per sting); multiple stings have been associated with kidney disease and even death in China.

Local hornet sting reactions include immediate pain, swelling, and redness at the sting site that often subsides within a few hours.

Regional reactions (exaggerated local reactions) occur in some individuals with extended swelling that can last 2-7 days. These reactions are not allergic in origin.

Anaphylactic reactions cause diffuse urticaria, pruritus, angioedema, bronchoconstriction, respiratory distress, hypotension, loss of consciousness, and cardiac arrhythmias. Typically, within 10 minutes of the sting, onset of life-threatening, anaphylactic signs will occur.

Acute myocardial infarction, hepatitis, intravascular hemolysis, rhabdomyolysis, acute renal failure, and glomerulonephritis following wasp stings have been rarely reported.


T63.451A – Toxic effect of venom of hornets, accidental, initial encounter

307427009 – Hornet sting

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Last Updated:05/11/2020
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Patient Information for Hornet sting
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Contributors: Medical staff writer


Bites or stings from insects (arthropods) are very common. Most reactions are mild and result from an allergic reaction to either the insect or the toxins injected with the bite or sting. Some people have severe reactions to the stings of:
  • Bees
  • Wasps
  • Hornets
  • Yellow jackets
These stings may require emergency help. The bites of most insects – such as ants, mosquitoes, flies, spiders, ticks, bugs, and mites – do not cause such a severe reaction.

Sometimes, it may be hard to tell which type of insect has caused the skin lesions, as many insect reactions are similar. Flying insects tend to hit exposed skin areas, while bugs such as fleas tend to hit the lower legs and around the waist, and often have several bites grouped together. Some individuals are far more sensitive to insects and have more severe reactions, so the fact that no one else in the family has lesions does not rule out an insect bite.

Who’s At Risk

Insect bites and stings are a problem in all regions of the world for people of all ages. In the Midwest and East Coast regions of the US, mosquitoes, flying insects, and ticks account for most bites. In drier areas of the Western US, crawling insects are more of a problem.

There is no proven effect of race or sex in terms of bite reactions. However, some individuals clearly appear more attractive to insects, perhaps related to body heat, odor, or carbon dioxide excretion.

Severe allergic reactions to stings occur in .5–5% of the US population.

Signs & Symptoms

Hornet sting reactions include immediate pain, swelling, and redness at the sting site that goes away in a few hours.

Flying insects tend to choose exposed areas not covered by clothing.

Common reactions to stings include:
  • Redness, pain, and swelling
  • Severe reactions such as facial swelling, difficulty breathing, and shock (anaphylaxis)
  • Fever, hives, and painful joints (though these reactions are not as common)

Self-Care Guidelines

For stings:
  • Wash the wound with soap and water.
  • Apply an ice pack or cold water for a few minutes.
  • Take acetaminophen for pain and an antihistamine (diphenhydramine or chlorpheniramine) for itching, as needed.

When to Seek Medical Care

When dealing with stings, be sure to watch out for symptoms such as:
  • Hives, itching, or swelling in areas beyond the sting site
  • Swelling of the lips or throat
  • Tightness in the chest or difficulty breathing
  • Hoarse voice or tongue swelling
  • Dizziness or loss of consciousness


Depending upon your reaction, your primary care giver might treat you in the following manner:
  • Antihistamines or corticosteroids
  • Epinephrine, antihistamines, corticosteroids, intravenous fluids, and oxygen (for anaphylaxis)
  • Injectable epinephrine, for those with known severe allergic reactions
  • Immunotherapy to reduce the chance of repeated severe reactions

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Hornet sting
A medical illustration showing key findings of Hornet sting : Edema, Erythema, Hornet sting, Painful skin lesion
Organism image of Hornet sting - imageId=3591244. Click to open in gallery.  caption: 'Hornet photographed in Guanacaste Province, Costa Rica.'
Hornet photographed in Guanacaste Province, Costa Rica.
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