Wuthrich wrote that adverse reactions to aspirin, additives such as tartrazine (Yellow 5) and the preservative benzoate are seen all over the world. It is described as an intolerance or pseudo-allergy possibly related to an imbalance of prostaglandin synthesis.
Testing 620 patients with urticaria (hives), bronchial asthma or chronic rhinitis, Wuthrich found that 26.5% of them were intolerant to aspirin and/or some of the additives.
QUOTE: “More than two thirds of the intolerant patients were improved by an elimination diet and by the avoidance of “aspirin-like” drugs.”
QUOTE: “…azo-dyes must no longer be used for colouring of drugs.”
NOTE: Unfortunately, more than 30 years later, his warning is still being ignored.
MedLine (article in German)