Food intolerance is difficult to diagnose either by analysis of symptoms or by any routine tests of blood or with allergen injections into the skin. The best approach is to immediately stop taking all possible causes of symptoms, and this necessitates adopting a strict diet and discontinuing all herbs and medications. After the body has been cleaned for a few days, each food and then medicine can be reintroduced one at a time on a daily basis. If one agent is the cause of the problem, the symptoms will reappear. This may take several weeks to accomplish and many people are unwilling to use such an arduous regimen.
A second approach is to use a non-sedating antihistamine drug routinely. A further approach is to simply give up taking any herbal preparation since these products contain multiple components whose toxic effects have not been adequately studied. Moreover, the benefits of some popular herbal mixtures are still inadequately investigated, and reliance on these may be hazardous since their eventual side effects may outweigh any possible benefit.
Despite all these concerns that have just been discussed, some investigators claim that the Chinese remedy reishi, which is a mushroom, may be of value in some food allergies. At present, the evidence for this is inadequate to justify making any recommendations for its use.