Originally, Saridon contained phenacetin. However, when it was discovered that phenacetin was carcinogenic and had a link to analgesic-induced nephropathy, Saridon was reformulated without this ingredient.
Phenacetin was once widely used as a remedy for fever and pain. It often took on the form “A.P.C” (aspirin-phenacetin-caffeine). But its use was stopped when the U.S. Food and Drug Administration tested lab rats with phenacetin and found it to be cancerous.
True enough, a 20-year study of 623 then-healthy women who regularly took phenacetin revealed those who took painkillers containing the active ingredient doubled their chances of dying. The study also found that they were “l6 times more likely to have a kidney disease or one in the urinary tract, almost twice as likely to die of cancer, and almost three times as likely to die of heart disease whilst the risk of developing cardiovascular disease was nearly two to one.” 
Phenacetin is now being used as a cutting agent to adulterate cocaine in the UK, owing to the similar physical features of the two drugs.
Despite reformulation, several adverse reactions have been reported against Saridon.
Twenty (20) adverse reactions to Saridon has been reported to Lareb, a Dutch Pharmacovigilance Center. Sixteen (16) of these were interpreted as allergic reactions; with 10 identified to be possibly fatal. In its fatal form, Saridon could induce dizziness, loss of consciousness, labored breathing, swelling of the tongue and breathing tubes, blueness of the skin, low blood pressure, heart failure and even death.
The WHO affirms this threat, with propyphenazone-induced allergic reactions having a Rate of Rise (ROR) of 18.2 as opposed to other tested analgesics that only have RORs of 1.4 and 0.8.