Adverse effects of Paracetamol,

In recommended doses, the side effects of paracetamol are mild to non-existent.In contrast to aspirin, it is not a blood thinner (and thus may be used in patients where coagulation is a worry), and it does not cause gastric irritation. Prolonged daily use increases the risk of upper gastrointestinal complications such as stomach bleeding,and may cause kidney or liver damage. Paracetamol is metabolized by the liver and is hepatotoxic; side effects may be more likely in chronic alcoholics or patients with liver damage.

Until 2010 paracetamol was believed to be safe in pregnancy (as it does not affect the closure of the fetal ductus arteriosus as NSAIDs can.) However, in a study published in October 2010 it has been linked to infertility in the posterior adult life of the unborn. Like NSAIDs and unlike opioid analgesics, paracetamol has not been found to cause euphoria or alter mood although recent research show some evidence that paracetamol can ease psychological pain. Unlike aspirin, it is safe for children, as paracetamol is not associated with a risk of Reye's syndrome in children with viral illnesses. Paracetamol use for fever in the first year of life was associated with an increase in the incidence of asthmatic symptoms at 6–7 years, and that paracetamol use, both in the first year of life and in children aged 6–7 years, was associated with an increased incidence of rhinoconjunctivitis and eczema.The authors acknowledged that their "findings might have been due to confounding by indication", i.e., that the association may not be causal but rather due to the disease being treated with paracetamol, and emphasized that further research is needed. Furthermore a number of editorials, comments, correspondence, and their replies have been published in The Lancet concerning the methodology and conclusions of this study. The UK regulatory body theMedicines and Healthcare products Regulatory Agency, also reviewed this research and published a number of concerns over data interpretation, and offer the following advice for healthcare professionals, parents, and care-givers: "The results of this new study do not necessitate any change to the current guidance for use in children. Paracetamol remains a safe and appropriate choice of analgesic in children. There is insufficient evidence from this research to change guidance regarding the use of antipyretics in children."

Chronic users of acetaminophen may have a higher risk of developing blood cancer.