Inductors of microsomal oxidation in the liver (phenytoin, ethanol, barbiturates, rifampicin, phenylbutazone, tricyclic antidepressants), ethanol and hepatotoxic drugs increase the production of hydroxylated active metabolites, which makes it possible to develop severe intoxication with small overdoses.
Ethanol promotes the development of acute pancreatitis.
Inhibitors of microsomal oxidation (incl. cimetidine) reduce the risk of hepatotoxic effects.
Reduces the effectiveness of uricosuric drugs.
Long-term use of barbiturates reduces the effectiveness of paracetamol. Long-term combined use of paracetamol and other non-steroidal anti-inflammatory drugs increases the risk of developing "analgesic" nephropathy and renal papillary necrosis, the onset of the terminal stage of renal failure.
Simultaneous long-term use of paracetamol in high doses and salicylates increases the risk of developing kidney or bladder cancer. Diflunisal increases the plasma concentration of paracetamol by 50% - the risk of developing hepatotoxicity.
Myelotoxic drugs increase the manifestation of hematotoxicity of the drug.