Published: March 1999

Resensitisation to Bee and Wasp Venom

Prescriber Update 18: 42–44
March 1999

Medsafe Editorial Team

Resensitisation to bee venom has been reported with ACE inhibitors and rarely with NSAIDs. Two well documented cases have been published, and one possible case reported to the Centre for Adverse Reactions Monitoring, of resensitisation to bee or wasp venom with a non-steroidal anti-inflammatory drug (NSAID) resulting in a serious anaphylactoid reaction. The mechanism may be the same as that which causes bronchospasm or urticaria in NSAID-sensitive individuals.
Resensitisation with an ACE inhibitor has been reported more frequently. For hypertensive patients at high risk of receiving insect stings or those undergoing desensitisation, consider alternative therapy to ACE inhibitors. Note that β-blockers are contraindicated during desensitisation programmes. If ACE inhibitors cannot be avoided and the patient is considered to be at risk of a severe vasodilatory reaction, take precautionary measures such as physical protection and/or having adrenaline on hand.

Resensitisation to bee or wasp stings with NSAIDs?

The Centre for Adverse Reactions Monitoring (CARM) has received a report of a major life-threatening anaphylaxis following a bee sting in a patient taking diclofenac who had been successfully desensitised many years previously. No information was supplied that would further support an association with the use of diclofenac in this particular case.

Two published1 cases more clearly implicate a non-steroidal anti-inflammatory drug (NSAID) with sensitisation to insect stings. Two individuals who had previously been exposed to bee or wasp stings with no or only local effect developed a severe anaphylactoid reaction within minutes of being stung. One patient was taking ibuprofen and the other diclofenac. Stings received after withdrawal of the NSAIDs produced no systemic reaction.

There do not appear to be any other published cases of NSAID-induced sensitisation to the stings of bees or wasps. The mechanism is unknown but it is probably the same as that which causes bronchospasm or urticaria in NSAID-sensitive individuals.2

Sensitisation to insect venom occurs with ACE inhibitors

ACE inhibitors also cause sensitisation or resensitisation to the stings of bees or wasps. Two men taking enalapril experienced anaphylactoid reactions following injections of wasp venom administered in a desensitisation programme.3 One man was able to tolerate the venom injections if he stopped enalapril 24 hours before administration of each injection. The other was switched to nifedipine. The association with enalapril was confirmed in each case by a positive rechallenge.

In another case a woman who was taking an ACE inhibitor experienced angioedema on 3 occasions following a bee sting. Prior to commencing and since discontinuing ACE inhibitor therapy she has developed only localised swelling after being stung by a bee.4 A similar case was reported to CARM. The patient experienced angioedema and urticaria on 4 occasions following a bee sting while taking an ACE inhibitor.5

Mechanism of sensitisation by ACE inhibitors may be via kinin potentiation

ACE inhibitors reduce the rate of breakdown of bradykinin, a potent vasodilator. As well, bradykinin increases vascular permeability and is involved in the mechanisms of acute hypersensitivity reactions. Venom, received either in a desensitisation programme or from an insect sting, increases histamine which is also a vasodilator. Possibly it is the combination that induces the anaphylactoid reactions seen in these patients. (See also the article on parenteral gold and acute vasodilatory reactions).

Avoid ACE inhibitors in those exposed to insect venom

It is not clear how frequently sensitisation to insect venom occurs with ACE inhibitors. It may be prudent to consider alternative antihypertensive treatment to ACE inhibitors in patients at high risk of receiving insect stings, or those undergoing desensitisation. Alternatively, temporary suspension of the ACE inhibitor before exposure to insect venom may be an option. Note that β-blockers should not be used as they also complicate desensitisation. If ACE inhibitors cannot be avoided and the patient is considered at risk of a severe vasodilatory reaction, measures to avoid exposure to insect stings should be taken and/or adrenaline for self-administration should be on hand for use when required.

  1. Bernard AA, Kersley JB. Sensitivity to insect stings in patients taking anti-inflammatory drugs. Brit Med J 1986;292:378-9.
  2. Insel PA. Analgesic-antipyretic and antiinflammatory agents and drugs employed in the treatment of gout. In Goodman & Gilman (Ed). The Pharmacological Basis of Therapeutics 9th Edn. 1996: New York, p.623.
  3. Tunon-de-Lara JM, Villanueva P, Marcos M, Taytard A. ACE inhibitors and anaphylactoid reactions during venom immunotherapy. Lancet 1992;340:908.
  4. Black PN, Simpson IJ. Angio-oedema and ACE inhibitors. Aust J Med 1995;25:746.
  5. Pillans PI, Coulter DM, Black P. Angioedema and urticaria with angiotensin converting enzyme inhibitors. Eur J Clin Pharmacol 1996;51:123-6.