| Liver damage is possible in adults who have taken 10g or more of paracetamol. Ingestion of 5g or more of paracetamol may lead to liver damage if the patient has risk factors, including the following ones: Risk factorsa) Long term treatment with carbamazepine, phenobarbitone, phenytoin, primidone, rifampicin, St John's Wort or other drugs that induce liver enzymes, orb) regular consumption of ethanol in excess of recommended amounts, orc) likely glutathione depletion, e.g. eating disorders, cystic fibrosis, HIV infection, starvation, cachexia.SymptomsSymptoms of paracetamol overdosage in the first 24 hours are pallor, nausea, vomiting, anorexia and abdominal pain. Liver damage may become apparent 12 to 48 hours after ingestion. Abnormalities of glucose metabolism and metabolic acidosis may occur. In severe poisoning, hepatic failure may progress to encephalopathy, haemorrhage, hypoglycaemia, cerebral oedema and death. Acute renal failure with acute tubular necrosis, strongly suggested by loin pain, haematuria, and proteinuria, may develop even in the absence of severe liver damage. Cardiac arrhythmias and pancreatitis have been reported.TreatmentImmediate treatment is essential in the management of paracetamol overdose. Despite a lack of significant early symptoms, patients should be referred to hospital urgently for immediate medical attention. Symptoms may be limited to nausea or vomiting and may not reflect the severity of overdose or the risk of organ damage. Management should be in accordance with established treatment guidelines.Treatment with activated charcoal should be considered if the overdose has been taken within 1 hour. Plasma paracetamol concentration should be measured at 4 hours or later after ingestion (earlier concentrations are unreliable). Treatment with N-acetylcysteine may be used up to 24 hours after ingestion of paracetamol, however, the maximum protective effect is obtained up to 8 hours post-ingestion. The effectiveness of the antidote declines sharply after this time. If required the patient should be given intravenous N-acetylcysteine, in line with the established dosage schedule. If vomiting is not a problem, oral methionine may be a suitable alternative for remote areas, outside hospital. Management of patients who present with serious hepatic dysfunction beyond 24h from ingestion should be discussed with a liver unit.Mild cases of overdose with antihistamines are mainly characterised by prominent anticholinergic effects including dry mouth, headache, nausea, tachycardia and urinary retention. Larger overdoses will have additional antihistamine effects which may depress or stimulate the CNS. In small children, the stimulatory effects predominate and clinical features include hallucinations, ataxia and convulsions. The child may be hot, flushed and have dilated pupils. Cardiorespiratory depression and coma can subsequently develop followed by rapid death. Overdosing diphenhydramine in adults usually results in drowsiness followed by convulsions and coma. Fever and flushing are uncommon. Overdosed patients are best treated by gastric lavage and supportive measures. Administration of activated charcoal may be useful. Convulsions can be controlled with diazepam. Peripheral anticholinergic effects can be controlled with subcutaneous neostigmine. | |