Background <p>Taurine is a powerful antioxidant necessary for mitochondrial function. Lactic acidosis is a complication encountered in the condition mitochondrial myopathy, encephalopathy, lactic acidosis and stroke-like episodes&#xa0;(MELAS), which can be successfully treated with supplemental taurine.&#xa0;Furthermore, taurine regulates the production of iron-dependent proteins such as ferritin that can act as chelating agents to sequester labile iron.</p> Case presentation <p>A 38-year-old Greek male with a β-zero thalassemia trait developed multiple severe symptoms soon after his first and only mRNA (Pfizer) SARS-CoV-2 vaccination that included hematological stress to be a candidate for blood transfusion. Amongst the hematological readings, the patient had lactate levels &gt; 4&#xa0;mmol/ml, indicating lactic acidosis, and ferritin levels &gt; 820 ng/ml, representing hyperferritinemia. Moreover, the patient has organic acid and plasma metabolite levels in the urine that are indicative of mitochondrial dysfunction. Regular taurine intake (500 mg/day) for years helped the patient control lactate and ferritin levels and avoid more serious clinical decompensation.</p> Conclusion <p>Regular taurine intake helps to avoid lactic acidosis and reverse hyperferritinemia after mRNA SARS-CoV-2 vaccination in a patient with β-zero thalassemia trait with no obvious genetic trait linked to mitochondrial myopathy, encephalopathy, lactic acidosis and stroke-like episodes. Taurine seemed to be protective for mitochondria.</p>