Paracetamol overdose

Author: Becky Maxwell, James Dear / Codes: HAP25, MHP4, PhC1, PhC4, PhP2, PhP3, SLO1, SLO2 / Published: 02/11/2017


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So the TOXABSE guidelines for staggered paracetamol overdose were updated last night. We bring you an up to date podcast on paracetamol overdose management recorded at the recent RCEM scientific conference with James Dear (@EdinClinTox) and Rebecca Maxwell (@maxirebecca). You may also want to check out Becky’s previous vodcast on paracetamol overdose published on RCEM Learning a few years back!

Current UK Management:

Paracetamol overdose is very common, the current management strategy isn’t optimal. Treatment doesn’t take into account the amount of paracetamol, when you took the overdose, whether you have liver injury – everyone gets treated with N. acetylcysteine (NAC) purely based on your weight – this is not optimal! There must be a better way.

Important points from the podcast:

  • Worldwide there is no consensus on which patient to treat – Treatment in UK is started if you are over the “100 line” on the nomogram – in American, Canada, Australia you only get treatment if you are over 150 lines on the nomogram. This is unlikely to change in the UK.
  • How do you identify liver injury? The guys in Edinburgh are currently developing a panel of biomarkers (MIR- 122), a bit like a troponin in chest pain, which is released early during liver damage. In the future could we use these to decide who needs treatment?
  • Staggered overdose – the NEW CHANGES these were published on TOXBASE last night… and announced on Twitter…

  • So what should you now do when a patient presents with a staggered overdose? 4 hours after the last ingestion in a staggered OD you should take blood – measure paracetamol level, INR and LFTS. If the following is correct in your patient then the patient DOES NOT NEED TREATMENT:
  • If paracetamol if below 10 AND
  • INR 1.3 or less AND
  • ALT is normal AND
  • The patient has no symptoms of liver damage (abdo pain, jaundice, vomiting)
  • Simon Thomas (Newcastle) did a Systematic review that could not find a case where a patient came to harm when there was no paracetamol in the blood and the ALT was normal
  • Is there a role for a shorter course of NAC than the current 21-hour regimen? In 2014 a paper was published in the Lancet looking at the shorter 12-hour regimen. This is now used as routine clinical practice in Edinburgh, Newcastle and ST Thomas’. The 21-hour regimen works but there are problems. More anaphylactoid reactions as large does given quickly in initial bag, multiple interruptions in treatment, longer length of stay.
  • The Lancet Paper compared the two regimens below (note the 21 hour regimen is the pre 2012 guidelines):

  • 12-hour regimen gives the same overall dose but gives it constantly over 12 hours rather than the 3 bags.
  • Is it as safe? Edinburgh are currently collecting data and it looks like preliminarily it is as effective, there are less anaphylactoid reactions, NNT is 10 people to prevent 1 reaction using the new regimen. This reduced time of NAC treatment could save the NHS millions! The data from Edinburgh is being presented at Pharmacology 2017 and is being submitted for publication soon! Watch this space…

Combine the recent guideline changes with the potential for a shorter regimen with the biomarkers and the future looks promising…


  1. fryerj4834 says:

    A point I raised on Twitter was the issue around the measuring of the paracetamol level. Its a staggered OD and so we are starting NAC straight away yes? Now if the presentation to hospital is 4 hours or more since last tablet then fine. But otherwise you will be putting a line in, starting NAC and then taking bloods to check paracetamol level, ALT and INR. However… As Toxbase themselves state, the paracetamol levels detected in lab are affected by NAC infusion and so will be under-reported by upto 40%. Ergo that result of 9 may actually be above that safe cut off after all… Just a thought.

  2. Neeraj Tekkar says:

    Biomarkers development for management Paracetamol Overdose will be a remarkable achievement. 4 hours waiting for blood test and unsure about exact time of intake as well staggered dose are the big pitfalls in managing these patients. Prolonged time of treatment with NAC and risk of anaphylaxis is another problem. Edinburg guys are doing excellent job ,I Wish them Success.

  3. Matt Walker says:

    Interesting read! If in doubt, always do the bloods for your peace of mind and for your documentation!! to protect yourself!! and also to protect the patient’s if early intervention identifed.

  4. iqbalj says:

    No harm in doing blood & if history is very much clear no harm in starting NAC in staggeredOD
    If paracetamol level not toxic NAC can be stopped
    2 hours first dose is sensible

  5. barnesch says:

    Interesting listen. Thank you for guidance.

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