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Paracetamol is the most common single agent involved in poisonous ingestions in young children. While there is potential for serious liver damage if a large dose is ingested, in practice, it is rare for a child to achieve toxic blood levels by ingesting paracetamol elixir (syrup).
Paracetamol is also commonly involved (often mixed with other drugs) in episodes of intentional self harm by teenagers. In this situation, relatively large amounts of paracetamol may have been ingested and this may not be disclosed in the history.
It is much more likely that a toxic level will be achieved under these circumstances.
Immediate threats to airway, breathing and circulation are RARE
in isolated paracetamol poisoning. Resuscitation should take
priority over decontamination or antidote administration.
Airway adjuncts and intubation as required. Consider intubation as per poisoning guideline.
Oxygen and ventilation if required.
Support perfusion as needed.
Treatment of hypoglycaemia
An accurate history of:
- The maximum possible dose and work out the dose per kg
- The time of ingestion
- Possible other drugs ingested
- Risk factors that may lead to increased hepatotoxicity (see below)
Consider the worse case scenario, e.g. that all the tablets have been ingested, that no significant spillage/vomiting has occurred and that one child has taken all the medication if multiple children were present. Also consider the worst case scenario with regard to the ingestion time, the possibility of an earlier ingestion time may place a patient above the treatment line, the possibility of a later ingestion time might require another paracetamol level to be measured.
In rare situations of single agent paracetamol ingestion, massive ingestions may be associated with early decreased level of consciousness and lactic acidosis. Good supportive care around:
- Correction of hypoglycaemia
There is NO role for decontamination in paracetamol elixir ingestions. Most of the drug is absorbed within 15 minutes of elixir ingestion and it is very unlikely that a child will receive any intervention within this time frame.
Decontamination with activated charcoal is only indicated if all of the following criteria is met:
- Paracetamol capsule or tablet is the ingestant AND
- If the dose ingested is >200 mg/kg AND
- The child presents within 2 hours of ingestion AND
- There is no co-ingestant that may lead to decreasing GCS or seizures
In single acute ingestion (<8 hours from
Maximum possible dose ≥ 200 mg/kg (ideal body weight) OR >10 g OR when dose is unknown or uncertain:
This includes most young people who present with ingestions as part of an episode of intentional self harm, unless the presence of paracetamol can be clearly excluded on history.
Tablets or capsules ingested: measure serum paracetamol at 4 hours post ingestion.
Elixir ingested: measure serum paracetamol at 2 hours post ingestion (the 2 hour level should only be relied upon in isolated paracetamol ingestions in WELL children)
- If the level is below 500 µmol/L at 2 hours then it is safe to discharge the child with no treatment.
- If the level is above 500 µmol/L at 2 hours, a further level should be measured at 4 hours. Treat as per nomogram.
- If the level is above 1500 µmol/L at 2 hours, commence acetylcysteine.
If the maximum possible dose is <200 mg/kg (ideal
body weight) AND total ingested dose is <10g :
NB: this should be based on ideal body weight in obese children
No intervention or drug level necessary
Younger children appear to be less susceptible to hepatotoxicity
The following situations require consultation with senior staff:
- Chronic/repeated ingestions
- Late presentation>8 hours post ingestion
- Unknown time of ingestion
- Symptoms/signs of toxicity: Anorexia, nausea, vomiting, RUQ tenderness
- Chronic illness - known liver disease, malnutrition
MJA 2008;188 (5); 296-301.
Ensure the correct units are used when applying plasma paracetamol results to the treatment nomogram. DO NOT confuse mmol/L with μmol/L, or traditional units (mg/L) with SI units (μmol/L).
ADHB laboratories report serum paracetamol levels as µmol/L.
If mg/L used please refer to: Daly FS, Fountain JS, Murray L et al. Guidelines for the management of paracetamol poisoning in Australia and New Zealand-explanation and elaboration. MJA 2008;188 (5); 296-301.
- Treatment with NAC is indicated for those children with levels above the threshold shown on the nomogram.
- NAC is 100% effective at preventing hepatotoxicity if started within 8 hours of ingestion
- Toxicity may still be reduced if it is started up to 24 hours after ingestion
- Delays in treatment with NAC can be associated with worse outcomes. Therefore treatment should be started immediately in children who present >8 hours after a significant ingestion or who are symptomatic of toxicity. Their further management should be discussed with senior staff.
- While it is recommended that NAC be administered with 5% glucose, there have been reports of life threatening hyponatraemia as a consequence of inappropriate volumes of 5% glucose. 0.9% saline may be used as a substitute. See table below. Care must be taken with infusion volumes if using 5% glucose.
Allergic reactions (flushing, urticaria, wheeze, angioedema, hypotension, fever) have been commonly reported but are rarely severe. They are dose dependant and usually occur during the rapid administration of Phase 1.
Minor symptoms (flushing, urticaria) can be managed with
hydrocortisone/promethazine and slowing (not stopping) the phase 1
infusion such that it is completed over 1 hour.
More serious symptoms (angioedema, wheeze, hypotension) require the infusion to be ceased and symptoms managed appropriately (see Anaphylaxis guideline). 1 hour after symptoms have abated, the infusion can be restarted, with caution, at the slower rate i.e. over 1 hour.
N-acetylcysteine therapy should NOT be stopped early even if a subsequent blood paracetamol level shows a result now below the line predicting toxicity (see stopping NAC below).
Only a small proportion of patients develop hepatotoxicity. Early symptoms include nausea, vomiting, abdominal pain and right upper quadrant tenderness. A majority of these still do not develop fulminant hepatic failure and recover fully. Patients who develop abnormal liver biochemistry require a continued infusion at the rate of last infusion stage.
Continue NAC until:
- The patient is clinically improving AND
- ALT <50U/L AND
- INR is improving and <2 AND
- The paracetamol concentration is less than 66 µmol/L
Table - NAC infusion guide
|Three stage 20 hour infusion for children <20kg|
|1.||150mg/kg NAC||diluted in 3ml/kg||5% glucose + 0.9% sodium chloride, infused over 15min|
|2.||50mg/kg NAC||diluted in 7ml/kg||5% glucose + 0.9% sodium chloride, infused over next 4 hours|
|3.||100mg/kg NAC||diluted in 14ml/kg||5% glucose + 0.9% sodium chloride, infused over the next 16 hours|
|Three stage 20 hour infusion for children >20 to 50kg|
|1.||150mg/kg NAC||diluted in 100ml||5% glucose + 0.9% sodium chloride, infused over 15min|
|2.||50mg/kg NAC||diluted in 250ml||5% glucose + 0.9% sodium chloride, infused over next 4 hours|
|3.||100mg/kg NAC||diluted in 500ml||5% glucose + 0.9% sodium chloride, infused over the next 16 hours|
|Three stage 20 hour infusion for children > 50kg|
|1.||150mg/kg NAC||diluted in 200ml||5% glucose,infused over 15-60min|
|2.||50mg/kg NAC||diluted in 500ml||5% glucose,infused over next 4 hours|
|3.||100mg/kg NAC||diluted in 1000ml||5% glucose,infused over the next 16 hours|
Timing of investigations
Recommended investigations according to time from paracetamol ingestion to acetylcysteine treatment
|Time (hours) from paracetamol ingestion to acetylcysteine||Investigations on admission||Investigations at the completion of acetylcysteine|
|Less than 8 hours||Serum paracetamol concentration||Nil*|
|8-24 hours||Serum paracetamol concentration and ALT||ALT and creatinine|
|Greater than 24 hours||Serum paracetamol concentration, ALT and INR||ALT, INR and creatinine|
|Patient who has an abnormal ALT||ALT Creatinine, LFT, INR, BSL, phosphate and VBG (for pH and lactate)||Repeat investigations every 12 hours
Creatinine, LFT, INR, BSL, phosphate and VBG
*NOTE: If symptoms of hepatotoxicity (ie. Nausea, vomiting, abdominal pain or tenderness) then repeat ALT. Or if initial concentration more than double the nomogram line, then repeat ALT and paracetamol concentration at the completion of acetylcysteine
Risk Factors for Paracetamol Toxicity
- Use of P450 2E1 inducing drugs eg phenobarbitone,
Induction of the P450 2E1 iso-enzyme leads to increased conversion of paracetamol to its toxic metabolite NAPQI.
- Malnourishment, fasting, acute or chronic illness
Recent significant fasting or illness, such as eating disorders (eg. Anorexia nervosa), or chronic illness such as HIV/AIDS may reduce intracellular glutathione levels increasing toxicity of NAPQI
- Gilbert's syndrome, Crigler-Najjar syndrome
Individuals suffering these genetic defects may be at greater risk of paracetamol toxicity
The vast majority of single paediatric accidental ingestions will require no treatment and will be discharged from the emergency department
Prior to discharge parental education re: safe storage of medication, child supervision etc should be undertaken
In the case of intentional overdose in an older child or adolescent, psychiatric review prior to discharge is mandatory.
If Non-Accidental Injury is a possibility involve the appropriate services.
The prevention of unintentional poisoning, including paracetamol, should be promoted throughout the community.
Child resistant closures and packaging have been shown to reduce the incidence of childhood poisoning.
Other measures that are likely to be successful include:
- Prescribing and dispensing smaller volumes of elixir.
- Educating families about safe storage of medications, out of reach of children with a child resistant latch.
- A home visiting program to target this advice.
Acute Ingestion Management
If elixir ingested, see section on elixir ingestion
Repeated supratherapeutic ingestion
|Age 0-6 years|
|≥200mg/kg over a single 24 hour period|
|≥150 mg/kg per 24 hour period over the preceeding 48 hours|
|≥100 mg/kg per 24 hour period over the preceeding 72 hours|
|Age >6 years|
|>200mg/kg or >10 g (whichever is lower) over a single 24 hour period|
|>150 mg/kg or >6 g (whichever is lower) over a single 24 hour period over the preceeding 48 hours|
|>100 mg/kg or >4 g (whichever is lower) over a single 24 hour period in patients with predisposing risk factors|
These children require a paracetamol level and an ALT level. If ALT normal and paracetamol level <120 μmol/L, these children are safe for discharge with no further treatment required.
Repeated supratherapeutic ingestion
Chiew AL, Fountain JS, Graudins A, et al. Summary statement. New guidelines for the management of paracetamol poisoning in Australia and New Zealand. MJA 2015;203: 215-218
Daly FS, Fountain JS, Murray L et al. Guidelines for the management of paracetamol poisoning in Australia and New Zealand-explanation and elaboration. MJA 2008;188 (5); 296-301
Chan C, Shepherd M. Profile of Paediatric Paracetamol Poisoning.
Prescott LF, Illingworth RN, Critchley JA et al. Intravenous N-acetylcysteine:the treatment of choice for paracetamol poisoning. Br Med J. 1979;2:1097-1100
Bailey B, McGuigan M. Management of anaphylactoid reactions to intravenous N-acetylcysteine. Ann Emerg Med 1998;31(6), 710-715
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- Date last published: 26 September 2018
- Document type: Clinical Guideline
- Services responsible: Children’s Emergency Department
- Author(s): Karen Quay
- Editor: Greg Williams
- Review frequency: 2 years
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