 The disruption of cell function that accompanies the condition can cause both mild and severe problems in people suffering from mitochondrial toxicity.The most commonly observed symptom is muscle weakness, or myopathy.Others include peripheral neuropathy (numbness in the fingers and toes) and pancreatitis (inflammation of the pancreas), with the most severe being lactic acidosis, in which a build-up of lactic acid in the tissues of the body leads to loss of energy, organ failure, and eventually death.