Complications
Nausea and vomiting should be treated with parenteral anti-emetic (e.g., ondansetron), and mixing of acetylcysteine in a flavoured drink (e.g., orange juice).
Patients who cannot tolerate oral acetylcysteine can be treated with intravenous acetylcysteine.[75]
Intravenous acetylcysteine administration results in an apparent decrease of vitamin K-dependent clotting factors (II, VII, IX, and X).[76][77][78] Clotting factors II, VII, IX, and X decrease within 4 hours of starting intravenous acetylcysteine therapy; maximum derangement in factors II, IX, and X occur at 1 hour and factor VII at 4 hours. The effect of intravenous acetylcysteine on clotting factors lasts for the length of the infusion, and it is relatively common for an INR to be 1.2 to 1.3 at the end of therapy.[76]
Monitor all patients closely for acetylcysteine infusion reactions over the first few hours.[51]
Adverse reactions to acetylcysteine are common, occurring in up to 30% of patients usually during or soon after the first induction.[3]
Adverse reactions are more likely if serum paracetamol concentrations are low or absent, and in women, patients with asthma, and those with a family history of allergy.[3]
Nausea, vomiting, flushing, urticarial rash, angioedema, tachycardia, and bronchospasm are relatively common. Hypotension and collapse are uncommon.[3]
In patients experiencing an adverse reaction consider temporarily stopping the acetylcysteine.
Re-start acetylcysteine infusion once the reaction has settled. Consider slowing the infusion rate (e.g., administer the first bag over twice as long as usual; the normal infusion rate can be used for subsequent bags).[3]
Consider giving inhaled salbutamol for wheezing and antihistamines for skin reactions.[3][51]
Give acetylcysteine even if the patient has a history of a previous adverse reaction as the benefits outweigh the risks.[51] Consider using a slower initial infusion of acetylcysteine in these patients to reduce the risk of a further reaction.[51]
In people with previous anaphylactoid reactions to acetylcysteine, before starting an infusion, consider:[3]
Prophylactic treatment with an antihistamine (follow local protocols)
Pretreatment with nebulised salbutamol in patients with a history of bronchospasm following acetylcysteine.
Advise all patients to seek medical attention if symptoms develop after discharge.[3]
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