Allergy to stinging insects and venom desensitisation

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What is a venom allergy?

A venom allergy is an allergic reaction to the venom in a bee or wasp sting. Allergic reactions to bee and wasp stings may affect the skin (hives, swelling of the face, lips and tongue), the gut (vomiting, diarrhea), breathing (wheezing or difficulty getting air in as the throat is closing up) or the circulation (low blood pressure which can cause fainting). Wasps and hornets have the same venom so people react to both insects. Bee venom is completely different. It’s very rare for people to have severe allergic reactions to both bees and wasps.

To test for venom allergy, we always start with a blood test. Skin tests are sometimes used afterwards when needed. It doesn’t always happen more than once. If a group of 10 people who reacted recently are stung again, around seven will react and three won’t react. Unfortunately we can’t tell which group you’ll fall into. The tests don’t help much here as they tend to stay positive. If you do get another reaction, the chances are that it will be the same or milder than the last one.

What should I do if I am stung?

• Have an adrenaline pen to hand, particularly when insects are active. Make sure that you know how to use it. We have a trainer device in clinic, and you can find a helpful video by entering ‘how to use my Epipen’ into a search engine.
• You should use the adrenaline pen if you are stung and get difficulty in breathing or feel faint. For milder symptoms such as hives, you won’t always need to use the pen. If things seem to be progressing very quickly you may want to use it as a precaution.

What is venom desensitisation?

Venom desensitisation (also known as immunotherapy) is a treatment used for severe venom allergy. It involves giving injections of venom. Over time, your immune system gets used to the venom so that you don’t react.

What does venom desensitisation involve?

The first phase of the treatment is known as updosing.

You will need to attend the allergy clinic every one to two weeks for at least eight visits. You’ll receive one or two injections per visit. If two injections are given, there will be a gap of 30 minutes in between the injections. You can leave the clinic 60 minutes after the final injection.

By the end of these visits you are protected from stings. After this you need to come for top up injections every 8 weeks. This stage of the treatment is known as maintenance. This continues for three years.At the end of a three year course the protection is permanent and you can be discharged.

The standard desensitisation product (brand name Alutard) contains an additive called aluminium hydroxide (also known as alum). This is included in many types of vaccine, in order to increase the immune response. Alum has been widely researched and has not been associated with any problems. However, some people prefer not to receive such products containing alum. Please let us know if you have any concerns about alum.

Are there side effects or risks?

Because you are allergic to venom, the treatment can cause allergic reactions. The main risk period for reactions is during the updosing phase, but reactions can happen at any point during your treatment.

Taking an antihistamine before you come can help.

You should stay in the department for 60 minutes after injections, as this is the risk period for severe reactions. If you do get an allergic reaction we will assess and treat anything that happens.

These reactions include:

Local reactions: The injection site may itch, swell and go red.
Anaphylaxis: This is a severe reaction and includes rashes, swelling (for example, of the lips) and breathing problems or fainting. Severe allergic reactions are very rare because the treatment is given very slowly and carefully.
Milder allergic reactions: These usually affect the skin only, with symptoms such as itching or hives. We see such symptoms quite often, and usually will just keep you under observation after taking an antihistamine tablet. The symptoms tend to settle down over time as your body gets used to the product; sometimes we may need to updose more slowly.

Some people report feeling very tired after these injections.

Are there any precautions?

• You should stay in the department for 60 minutes after injections, as this is the risk period for severe reactions.
• Please don’t come for immunotherapy if you are not well, for example, with infection.
• If you have asthma, it should be well controlled. If your asthma isn’t controlled on the day we may advise on treatment and delay the immunotherapy.
• Vigorous exercise such as running, gym or exercise classes is not recommended straight after the dose.
• Please let us know if you are taking B Blocker tablets.
• Some people take an antihistamine tablet before the appointment, which can help with the local reactions at the injection site.

What if I am pregnant or become pregnant during the treatment?

Pregnancy should be avoided during the updosing phase. However, if you become pregnant during the maintenance phase it’s not a problem.

Does the treatment work?

This is a very effective treatment for venom allergy. Once the maximum dose is reached, around 19 out of 20 people have no reaction to stings. 1 out of 20 people have a mild reaction (for example, skin only).

The benefits are long term, even once the treatment is completed.

Most people can stop carrying adrenaline pens once the maximum dose is reached. We recommend that you keep a device if you are at risk of multiple stings eg roofers, pest controllers, tree surgeons. Most beekeepers stop carrying adrenaline pens once they’ve been stung again. Some people prefer to keep the adrenaline pens for security regardless.

Where do I need to go for my treatment?

Desensitisation clinics are held in Main Outpatient Department, Royal Sussex County Hospital on Wednesday mornings. We also have a clinic on Monday mornings which you can use for maintenance doses once the maximum dose has been reached. It’s best to stick to Wednesdays for updosing as more staff are available in case of problems. You will be given an appointment, but you don’t need to stick to the stated time: just turn up whenever convenient between 8am and 11.30am.

Who can I contact for further information and advice?