Chemical Intolerance identifies phenolic (aromatic) chemical compounds present in natural foodstuffs, pollens, certain food additives, tobacco smoke, perfumes, air pollution, etc., as nonimmunologic, but pharmacologic activators of allergic reactions in chemically intolerant individuals. Biochemical pathway sequences, with supporting scientific literature, are outlined to elucidate the mechanisms associated with formation of inflammatory mediators (prostaglandins, thromboxanes, and leukotrienes) upon activation by phenolic compounds and other chemical stimulants. The role of these inflammatory agents in respiratory, gastrointestinal, neurological, cardiovascular, and other disorders is discussed. Treatment modalities using precise dosages of selected phenolic compounds are outlined to provide clinicians with an effective means of therapy. The author also shares his own experience and personal findings based on 20 years of research, including his recommendations for therapy.