Given the propensity of the Macedonian aristocracy to assassination, it is scarcely surprising that allegations of foul play have been made about the death of Alexander. Diodorus, Plutarch, Arrian and Justin all mention the theory that Alexander was poisoned. Plutarch dismisses it as a fabrication, but both Diodorus and Arrian say that they only mention it for the sake of completeness. The accounts are nevertheless fairly consistent in designating Antipater, recently removed from the position of Macedonian viceroy, and at odds with Olympias, as the head of the alleged plot. Perhaps taking his summons to Babylon as a death sentence in waiting, and having seen the fate of Parmenion and Philotas, Antipater arranged for Alexander to be poisoned by his son Iollas, who was Alexander's wine-pourer. There is even a suggestion that Aristotle may have had a hand in the plot. Conversely, the strongest argument against the poison theory is the fact that twelve days had passed between the start of his illness and his death; in the ancient world, such long-acting poisons were probably not available.
Several natural causes (diseases) have been suggested as the cause of Alexander's death; malaria or typhoid fever are obvious candidates. A 1998 article in the <em>New England Journal of Medicine</em> attributed his death to typhoid fever complicated by bowel perforation and ascending paralysis, whereas another recent analysis has suggested pyrogenic spondylitis or meningitis as the cause. Other illnesses could have also been the culprit, including acute pancreatitis or the West Nile virus. Natural-cause theories also tend to emphasise that Alexander's health may have been in general decline after years of heavy drinking and his suffering severe wounds (including one in India that nearly claimed his life). Furthermore, the anguish that Alexander felt after Hephaestion's death may have contributed to his declining health.
The most probable cause of Alexanders death is however, the result of overdosing on medicine made from Hellebore, deadly in large doses. The very few things we do know about his death, can today be explained only with accidental hellebore-poisoning.