| At the recommended dosage, paracetamol may cause the following side effects:• Allergic reactions - rare but may include skin rash, drug fever, mucosal lesions.• Effects on CNS - drowsiness, impaired mental functions• Effects on GI system - Chronic hepatic necrosis has been reported in a patient who took daily therapeutic doses of paracetamol for about a year, and liver damage has been reported after daily ingestion of excessive amounts for shorter periods. Acute pancreatitis has been reported. A review of a group of patients with chronic active hepatitis failed to reveal differences in the abnormalities of liver function in those who were long-term users of paracetamol, nor was the control of their disease improved after paracetamol withdrawal.• Effects on CVS - toxic myocarditis.• Effects on blood - methaemoglobinaemia, neutropenia, pancytopenia, leukopenia, thrombocytopenic purpura, haemolytic anaemia and agranulocytosis.• Effects on GU system - Nephrotoxicity following therapeutic doses of paracetamol is uncommon, but papillary necrosis has been reported after prolonged administration.• Other effects - Most reports of adverse reactions to paracetamol relate to overdosage with the drug.Adverse effects of opioid treatment which have been reported include:• Allergic reactions (may be caused by histamine release) - including rash, urticaria, difficulty breathing, increased sweating, redness or flushed face.• Effects on CNS - confusion, drowsiness, vertigo, dizziness, changes in mood, hallucinations, CNS excitation (restlessness/excitement), convulsions, mental depression, headache, trouble sleeping, or nightmares, raised intracranial pressure, tolerance or dependence.• Effects on GI system - constipation, GI irritation, biliary spasm, nausea, vomiting, loss of appetite, dry mouth, paralytic ileus or toxic megacolon.• Effects on CVS - bradycardia, palpitations, hypotension.• Effects on sensory system - blurred or double vision.• Effects on GU system - ureteral spasm, antidiuretic effect.• Other effects - trembling, unusual tiredness or weakness, malaise, miosis, hypothermia.• Effects of withdrawal - abrupt withdrawal precipitates a withdrawal syndrome. Symptoms may include tremor, insomnia, nausea, vomiting, sweating and increase in heart rate, respiratory rate and blood pressure. NOTE - tolerance diminishes rapidly after withdrawal so a previously tolerated dose may prove fatal.• Regularly prolonged use of dihydrocodeine is known to lead to addiction and tolerance. Symptoms of restlessness and irritability may result when treatment is then stopped.• Prolonged use of a painkiller for headaches can make them worse. | |