Insect venom allergies: Short-term and long-term treatment

Photo of a boy having allergen-specific immunotherapy (PantherMedia / Andriy Popov)

Insect venom allergies are most commonly caused by bee stings and wasp stings. More severe allergic reactions can quickly be treated using an emergency kit. Allergen-specific immunotherapy (desensitization) is often successful in the treatment of insect venom allergies: It can prevent severe allergic reactions.

Insect stings or bites can have unpleasant consequences in people who are allergic to them: Within a very short amount of time they can cause swelling around the sting or bite, nausea, dizziness, a rash, breathing difficulties and – in rare cases – even life-threatening cardiac arrest.

Living with this risk can be frightening. But it's still important to stay calm if you get stung by an insect that you're allergic to. Severe consequences are very rare if the medications in the emergency kit are used soon enough.

Unlike many other allergies, insect venom allergies can be treated with allergen-specific immunotherapy (desensitization). This involves allowing the immune system to gradually get used to the insect venom. Most people who complete this treatment are no longer at risk of having dangerous reactions to the insect venom for a long time afterwards.

How should insect stings be handled?

It is always important to be prepared for an anaphylactic reaction – in other words, to always have an emergency kit with you if there's a risk of being stung. The kit contains an adrenaline (epinephrine) injection, oral steroid medication in the form of a tablet or liquid, and an antihistamine medication. These allow people to treat their allergy symptoms quickly and effectively themselves.

It's important to react immediately after being stung:

  • Take just the antihistamine pill at first if the reaction is mild and you don't have breathing difficulties or circulation problems.
  • Depending on the severity of the skin reaction around the sting, take the steroid medication too.
  • Inform people who are nearby in case the allergic reaction becomes more severe and they have to help.
  • If the allergic reaction causes more serious problems such as breathing difficulties, nausea, circulation problems or swelling in the mouth and throat, it's important to inject the adrenaline into the thigh muscle as soon as possible.
  • If you are stung by a bee, pull the stinger out within 20 to 30 seconds in order to prevent all of the venom from entering your body. Take care not to pinch the stinger while removing it. Doing so may squeeze more venom into the skin. Instead, scrape across the stinger using a fingernail. This will pull it out.

The site of the sting can be covered using a cool, wet flannel. The flannel is left there for about 20 minutes and, if needed, reapplied after a few hours. The swelling at the site of the sting can also be treated using a steroid cream, which is applied regularly for several days.

If your allergy symptoms are severe, it's a good idea to see a doctor.

People who have already had successful allergen-specific immunotherapy don't need to take or inject any medication at first. Allergic reactions are much less likely to occur after this kind of treatment. But if the sting causes more than just a local skin reaction, the emergency medication is used.

There are patient education programs to help people learn how to manage the risk and use the emergency treatment.

How can insect venom allergies be treated in the long-term?

Allergen-specific immunotherapy (SIT, also known as desensitization) can be a helpful long-term treatment. It involves regularly injecting small doses of the insect venom under the skin. As with vaccines, the immune system gradually gets used to the allergen. After a while the body no longer reacts to the insect venom in such an extreme way.

It takes three to five years to complete allergen-specific immunotherapy. In some rare cases, doctors even recommend life-long immunotherapy.

Who is this treatment suitable for?

Allergen-specific immunotherapy is suitable for people who have anaphylactic reactions. It is particularly considered as a treatment option for people who react very strongly to insect venom – for instance, those who have already had cardiac arrest after being stung. People who have mastocytosis (a mast cell disorder) may also be advised to have immunotherapy for long-term treatment results. In this rare disorder, certain immune cells in the tissue start multiplying a lot. Mastocytosis can occur in various organs, causing symptoms such as stomach ache, itching, exhaustion and muscle pain.

If a person's only reaction to an allergen so far is a skin reaction, they generally won't need to have allergen-specific immunotherapy. In most cases they won't start having more dangerous allergic reactions later on, either.

People can have allergen-specific immunotherapy from the age of two. Women who have already started having this treatment can carry on having it if they get pregnant. But it isn't advisable to start during pregnancy. The treatment could possibly lead to an extreme allergic reaction in the mother, which could also affect the unborn child. For this reason, women who are planning to become pregnant should consider immunotherapy far enough in advance.

Some medications, such as beta blockers and ACE inhibitors, shouldn't be taken during immunotherapy for an insect venom allergy. Doing so increases the risk of having a severe allergic reaction.

Factors that play a role when deciding whether or not to have allergen-specific immunotherapy include

  • how severely you react to stings,
  • how likely you are to be stung, and
  • how likely the side effects of treatment are.

What does allergen-specific immunotherapy involve?

When it comes to the treatment of insect venom allergies, immunotherapy can currently only be carried out using injections. A solution containing gradually increasing small doses of the allergen is injected into the fatty tissue of the upper arm. Unlike with some other allergies, it isn't yet possible to carry out this treatment using drops or tablets.

The injections are usually given once a week in the first few weeks of treatment, and then every four to eight weeks after that. The dose can also be increased at a faster rate, by injecting a solution several times a day over the space of two days. This has to be done in a hospital, though, and is more likely to cause side effects. When carried out within the normal time frame, patience is needed for this treatment. It takes three to five years to complete.

The desensitization process is quite demanding for the immune system and metabolism. People are advised to avoid strenuous physical activity, sports and saunas on the days when they are given an injection.

How effective is immunotherapy?

The aim of allergen-specific immunotherapy is to prevent or reduce the severity of anaphylactic reactions. Research has shown that immunotherapy is very effective in the treatment of insect venom allergies. In the first few years after treatment, about 90% of people don't have anaphylactic reactions to insect stings.

The effects of treatment probably don't last for the rest of your life, though. They sometimes wear off after a number of years. If that happens, you can talk to your doctor about whether it would be a good idea to repeat the treatment.

What are the side effects of allergen-specific immunotherapy?

Most people have red and swollen skin at the site of injection. But this reaction dies down during the course of the treatment. Steroid creams or gels can be applied to the skin to reduce these side effects.

Other possible side effects include mild anaphylactic reactions that cause tiredness and headaches. But very severe anaphylactic shock, leading to circulation problems or breathing difficulties, is very rare. If it does occur, it often starts within 30 minutes of the injection. So it is important to stay in the doctor's waiting room for at least half an hour after having the injection. Anaphylactic reactions are more common in people who are having immunotherapy for bee sting allergies: They occur in about 14 out of 100 people who have bee sting allergies, compared to about 3 out of 100 people who have wasp sting allergies.

People with certain heart and immune diseases (e.g. coronary artery disease, multiple sclerosis) are more likely to have severe reactions to the treatment.