At a glance

  • Insect venom allergies may lead to only mild symptoms, but can also be life-threatening.

  • They are most commonly caused by venom in bee or wasp stings.

  • It's important to treat a sting quickly.

  • If anaphylactic shock occurs: Call for emergency medical services immediately.

  • Immunotherapy can gradually reduce the allergic reaction over time.

Introduction

Photo of a family having a picnic (PantherMedia / Monkeybusiness Images)

We all get stung or bitten by insects every now and then – and most people end up with a small, red, itchy bump as a result. But those who are allergic to insect stings or bites may react to them strongly, and the reaction might even be life-threatening in rare cases.

In insect venom allergies, the body’s immune system attacks certain parts of proteins that enter the body when the insect bites or stings. It's not known why that happens. But this allergy doesn’t develop after the first sting or bite: Sometimes people get stung or bitten over many years without having an unusual reaction. Over time, though, their bodies become more sensitive to the venom in the sting or bite (sensitization) and they then suddenly have an allergic reaction to it.

Symptoms

Allergic reactions to insect venom cause the skin around the bite or sting to become very swollen. The swelling often has a diameter of more than 10 cm and lasts longer than 24 hours. It usually hurts, burns or itches a lot.

Stings inside the mouth or throat can cause the airways to become swollen, making it harder to breathe. This is particularly dangerous for people who have an allergy. But the swelling is rarely bad enough to lead to suffocation.

If the symptoms affect the entire body, it's known as an anaphylactic reaction. This reaction may be mild, but it can also be life-threatening. The milder reactions include hives (a raised skin rash – also known as nettle rash), itching all over the body, dizziness, stomach and bowel problems, and nausea. People may also generally feel weak, have a swollen face or hands, or have problems swallowing. Severe anaphylactic shock leads to breathing problems, a sudden drop in blood pressure, loss of consciousness or even cardiac arrest (where the heart stops beating).

The symptoms usually occur soon after the person is bitten or stung. In rare cases, though, they may only occur a few hours later. When someone has an anaphylactic reaction, the symptoms might go away at first, but then return within eight hours.

Learn more

Causes and risk factors

Some people are generally more likely to have allergies. But it isn’t known why some people have an insect venom allergy and others don’t.

Bee sting allergies and wasp sting allergies are the most common allergic reactions to insect venom. Bee stings are more likely to lead to serious allergic reactions than wasp stings are. Allergic reactions to hornet stings (usually in people who are allergic to wasp stings) or bumble bee stings (usually in people who are allergic to bee stings) are much less common. Mosquito bites, horsefly bites and ant bites hardly ever lead to allergic reactions in Germany and similar countries, apart from near to the area of skin that was bitten.

Knowing the difference between the behavior of bees and wasps helps to avoid them and react properly if you get stung. And knowing which insect stung you can be important for the diagnosis:

Bees Wasps
  • don’t tend to be aggressive – unless they feel threatened.
  • are active between the spring and late summer.
  • lose their stinger when they sting someone; it usually gets stuck in the skin.
  • are typically found flying close to beehives and flowers.
  • tend to be more aggressive – they are more likely to feel threatened by movements and attempts to blow them away.
  • are mainly active between summer and late fall.
  • keep their stinger after stinging someone.
  • often fly around food and rubbish.

Prevalence

About 2% of the population react to insect bites and stings with symptoms that affect more than just the surrounding area of skin.

Some people are stung or bitten more often than others, and are more likely to become allergic to the venom as a result. These include beekeepers and people who live with them. Other people who are at higher risk include those who work in bakeries, sell fruit or work on a farm.

Effects

Generally speaking, allergic reactions to insect bites or stings don’t have any lasting harmful effects.

About 20 deaths due to bee sting, wasp sting, or hornet sting allergies are reported every year in Germany. The actual number is probably a little higher because allergic reactions aren’t always recognized as the cause of death.

Diagnosis

Before performing a physical examination, the doctor will first ask about the exact symptoms. It isn’t always easy to tell the difference between wasp stings and bee stings, so it’s important to describe where you were when you were stung, and how the insect was behaving at the time.

Skin tests and blood tests are only done if the allergy affects more than just the local area of skin. These tests check whether the immune system overreacts to certain triggers.

In a skin prick test, solutions of potential food allergens are put on the forearm with enough space between them and the skin is gently pricked so they can get into the skin. The skin is then observed to see whether it turns red or itchy and bumpy. In the blood test, the doctor checks whether a blood sample contains antibodies to insect venom.

In other allergies, a provocation test is sometimes used as well. That involves exposing the body to increasing doses of the suspected trigger in order to see whether there’s an allergic reaction. But this test can lead to severe reactions in people with insect venom allergies, so it is only done in exceptional cases and in specialized centers.

Prevention

The main way to prevent allergic reactions is to avoid being bitten or stung by the insect. To lower the risk, the following strategies are recommended:

  • Be careful when eating outdoors, and clear the table as soon as you have finished eating. Avoid eating outdoors if there are a lot of insects flying about.
  • Don’t spend time near rubbish.
  • Cover up your drinks and use a straw.
  • Clean your mouth and hands after eating.
  • Don’t swat at wasps or bees – they usually sting to defend themselves. Stay calm and move slowly.
  • Cover up your skin with clothing.
  • Keep windows closed during the day.
  • Stay away from beehives and wasps' nests.

Treatment

If someone is stung or bitten by the insect that they are allergic to, they will usually first take antihistamines in the form of a tablet. Depending on how severe the skin reaction is, a steroid medication may be used too. If more serious symptoms develop – such as breathing problems, nausea, circulation problems or swelling in the mouth and throat – adrenaline must be injected as soon as possible. If anaphylactic shock occurs, call for emergency medical services immediately (112 in Germany and many other European countries or 911 in the U.S.)

People who tend to have more severe allergic reactions are often advised to have a treatment known as allergen-specific immunotherapy (also known as desensitization). After having this treatment, the allergic reaction to the insect sting is usually much weaker over the long term, or the allergy may even go away completely.

People who have a confirmed insect venom allergy are advised to carry a medical ID card or bracelet on them at all times, to let people know what they are allergic to in an emergency.

Learn more

Further information

When people are ill or need medical advice, they usually go to see their family doctor first. Read about how to find the right doctor, how to prepare for the appointment and what to remember.