Acetylcysteine Intravenous Infusion for Adults

Who can administer

May be administered by registered competent doctor or nurse/midwife

Important information

  • Overdose algorithm is different for the intravenous formulation of paracetamol. Advise contact National Poisons Information Centre (NPIC)
  • Blood samples taken less than four hours after a paracetamol overdosage give unreliable estimates of the serum paracetamol concentrations
  • Anaphylactoid hypersensitivity reactions may occur, particularly with initial loading dose.  Patient should be carefully observed.  Most anaphylactoid reactions can be managed by temporarily suspending the acetylcysteine infusion, administering appropriate supportive care and restarting at a lower infusion rate (50mg/kg over four hours, followed by the final 16 hour infusion)
  • A previous anaphylactoid reaction to acetylcysteine may not be a contraindication for use.  Contact NPIC (ref 1)

Available preparations

Parvolex 2g per 10ml ampoule

Acetylcysteine 2g per 10ml ampoule


Already in solution

Draw up using a 5 micron filter needle

Dilute further prior to administration

Infusion fluids

Glucose 5% preferred (or Sodium chloride 0.9%)

Methods of intravenous administration

Intermittent intravenous infusion

Three different bag volumes and rates recommended for paracetamol poisoning (see "Dose")

Glucose 5% is the preferred diluent in these circumstances.

Dose in adults

Paracetamol poisoning

  • Doses should be administered sequentially with no break between infusions.  Each infusion to be started immediately after the previous one finishes
  • The patient should receive a total dose of 300mg/kg over a 21 hour period
  • Weigh patient to determine the correct weight band (maximum weight of 110kg should be used in calculations)
  • Use the dosage table below to determine the appropriate volume of acetylcysteine (ampoule volume) to be added to the infusion fluid for each of the three infusion periods
  • First infusion: Add the appropriate volume of acetylcysteine to 200ml of the infusion fluid and infuse over 1 hour
  • Second infusion: Add the appropriate volume of acetylcysteine to 500ml of the infusion fluid and infuse over the next 4 hours
  • Third infusion: Add the appropriate volume of acetylcysteine to 1000ml of the infusion fluid and infuse over the next 16 hours
  • Continued treatment with NAC beyond 21 hours may be necessary depending on the clinical evaluation of the individual patient.  If treatment is continued, it should be given at the dose and rate used in the third infusion
Acetylcysteine for Adults  Each ampoule contains 2g/10ml (200mg per ml)
Regimen First infusion Second infusion Third infusion
Infusion fluid 200ml Glucose 5% (preferred) or Sodium Chloride 0.9% 500ml Glucose 5% (preferred) or Sodium Chloride 0.9% 1000ml Glucose 5% (preferred) or Sodium Chloride 0.9%
Duration of infusion 1 hour 4 hours 16 hours
Drug dose 150mg/kg acetylcysteine 50mg/kg acetylcysteine 100mg/kg acetylcysteine
Patient weight (see note 1 below) Ampoule volume (see note 2 below) Infusion rate Ampoule volume (see note 2 below) Infusion rate  Ampoule volume (see note 2 below)  Infusion rate 
kg  ml ml per hour  ml  ml per hour  ml  ml per hour 
40 to 49 34  234  12   128   23 64 
50 to 59 42   242  14  129  28  64
60 to 69 49   249  17  129  33  65
70 to 79 57   257  19  130  38  65
80 to 89 64   264  22  131  43  65
90 to 99 72   272  24  131  48  66
100 to 109 79   279  27  132  53  66
110 or greater (maximum dose) 83   283  28  132  55  66

Note 1: Dose calculations are based on the weight in the middle of each band.  If the patient weighs less than 40kg you will need to calculate the dose out 

Note 2: Ampoule volume has been rounded up to the nearest whole number 


  • Store below 25° C


SPC September 2019

1: Toxbase- accessed 29th Sept 2021

Therapeutic classification

Emergency treatment of poisoning

IV Guide Type