Salicylates:

• stimulate the respiratory center in the brainstem, causing respiratory alkalosis
• interfere with the Krebs cycle, limiting ATP production, leading to an anaerobic metabolism
• uncouple oxidative phosphorylation, causing accumulation of pyruvic and lactic acid and heat production, resulting in acidosis and hyperthermia
• increase fatty acid metabolism, generating ketone bodies

Overall, this results in a mixed respiratory alkalosis and metabolic acidosis. 

References