Desensitisation (or immunotherapy) is a highly effective treatment for severe bee and wasp sting allergy. Desensitisation is only considered for severe reactions if you remain at high risk of being stung in the future. The effect of the treatment is to substantially reduce your allergic reaction to future stings, by giving small amounts of the allergen (a substance that causes an allergy) at safe intervals.
Desensitisation involves regular injections under the skin of your arm. Increasing amounts of bee or wasp venom is given weekly for 12 to 15 weeks until the top dose is achieved. This is followed by injections at two to eight week intervals at the top dose for a further three years.
Before each injection, you will have your pulse, blood pressure and peak respiratory flow measured by the nurse. The doctor will then ask you questions about your general health and whether you developed an allergic reaction with any previous injections. The doctor or nurse gives the injection in the outer aspect of the upper arm. You may experience some discomfort at the site of the injection. After your injection, it is necessary to remain in the clinic under observation for one hour. During this time, you will have further measurements of your pulse, blood pressure and peak respiratory flow. At intervals during the three-year desensitisation you will be asked to have a blood test to monitor the specific antibodies to venom
The injection site may become slightly swollen and itchy for up to two to three days but these reactions generally improve once the top dose is reached. Some patients develop tiredness for up to 24 hours after the injection especially during the first three months. Less commonly, reactions that are more serious can occur such as a generalised itchy rash, asthma, itchy eyes or nasal symptoms. All these are readily treatable.
Severe allergic reactions
Occasionally a severe allergic reaction can occur soon after the injection and will be treated quickly by the clinic doctor. These severe reactions are the reason why it is necessary to have this form of treatment in a specialised Allergy Clinic run by staff that are highly trained in the treatment of allergy.
Effectiveness of desensitisation
Bee and wasp venom desensitisation is highly effective (85-95%) and the majority of patients will benefit. However, long-term improvement is only seen if you complete the three-year course of treatment.
It is very important that you tell the doctor which medications you are taking or if you start a new drug during the desensitisation period. Most drugs can be continued during desensitisation but beta-blockers, which are often prescribed for blood pressure, migraine or heart conditions must be stopped before treatment is started.
Precautions after an injection
Exercise can increase absorption of allergen from the injection site and can lead to increased risk of side effects. We would therefore recommend that vigorous exercise such as cycling home or taking part in any activity that involves strenuous use of your arms should not be undertaken for 24 hours after the injection.
If you are unwell
If you are unwell with a cold, flu or have a fever for any other reason your injection will be postponed until you recover. Please contact the clinic on 01223 216645. Similarly, if you have other allergic symptoms, which have become worse recently, for example hay fever or asthma, the injection dose may be either reduced or postponed.
Desensitisation is not usually started or continued during pregnancy because of the risk to the baby should a severe reaction occur.
We are smoke-free
Smoking is not allowed anywhere on the hospital campus. For advice and support in quitting, contact your GP or the free NHS stop smoking helpline on 0800 169 0 169.
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Cambridge University Hospitals
NHS Foundation Trust
Hills Road, Cambridge
Telephone +44 (0)1223 245151