The composer Wolfgang Amadeus Mozart died on 5 December 1791 at the age of 35. The circumstances of his death have attracted much research and speculation.
Mozart himself was convinced that he was being poisoned. He became increasingly unwell, but then had a brief period of recovery, However :
Mozart's worst symptoms of illness soon returned, together with the strong feeling that he was being poisoned. He became bedridden on 20 November, suffering from swelling, pain and vomiting. From this point on, scholars are all agreed that Mozart was indeed very sick, and he died about two weeks later, on December 5."
Source Wikepedia
Current theories of possible causes include :