Several reports have suggested that the onset of allergic phenomena in predisposed subjects may trigger an angina episode, and this association has been described as Kounis syndrome. However, no previous reports have convincingly demonstrated a causal relationship between allergic reactions and acute coronary syndrome, and other possible mechanisms have not been excluded as causes of angina onset. We present a patient with chronic metabolic acidosis because of ureteroileourethrostomy and history of hypersensivity to beta-lactamic agents. He suffered three episodes of documented vasospastic angina, two of them related to amoxicillin administration; however, worsening of metabolic acidosis was found in all three episodes. This report shows that although allergic phenomena could play a role triggering this kind of acute coronary syndrome, other uncommon underlying mechanisms should be considered before the diagnosis of Kounis syndrome is established.