Immunotherapy - a series of injections that desensitise allergy-prone individuals - led to the deaths of a number of patients treated by GPs in the early 1980s after they suffered anaphylactic shock (sudden collapse) on being exposed to doses of the substance to which they were sensitive.
The deaths led to restrictions on the therapy, allowing its use only in specialist hospital allergy clinics in which full resuscitation facilities were available.
Immunotherapy is the only treatment that targets the causes of allergy rather than the symptoms, but it has been little used in Britain for the last decade. The long period of treatment required - three to five years - and the expense makes it suitable only for severely affected individuals, though it is widely used in Germany and Scandinavia.
The WHO report, published yesterday, was drawn up by a panel of experts from around the world and sets standards for the treatment. It can be used for people who are hypersensitive to bee and wasp stings, cats and other pets, who suffer hay-fever, asthma and house dust-mite allergies and who have allergic rhinitis or conjunctivitis.
The report, launched at the 17th Congress of the European Academy of Allergology and Clinical Imunology in Birmingham, says that if started early immunotherapy "may modify the long term progress of allergic inflammation and disease."
Professor Robert Davies, director of the allergy clinic at St Bartholomew's Hospital, London, said: "Immunotherapy has the potential to alter the immune response and in some people to get rid of their allergy altogether. With the explosion in allergies around the world, it is important to focus on the cause and try to stop people becoming allergic in the first place or reverse their immune response.
"Although there is now excellent treatment for allergies available, all the creams, tablets and inhalers only suppress the symptoms, they do not cure them."
Professor Davies said there is growing evidence of immunotherapy's efficacy against a wider range of allergies than pollen and stings. However, funding was difficult to obtain.
"It has taken some while for the authorities to recognise we have an epidemic of allergies. But in a cash-strapped NHS the view is that the walking wounded have to get on with it while the service copes with the mortally ill."
The WHO report says that new technologies and improved knowledge about the mechanisms of allergic disease may alter the way immunotherapy is used in the future.
"These advances should result in new, safer and substantially more effective methods of manipulating the human immune response," it says.Reuse content