Nursing care
Succinylcholine: what to check before you give it
Written and reviewed by Dana Whitfield, RN, MSN · 4 min read · Updated September 2026
Short answer
Succinylcholine is a depolarising neuromuscular blocker used for rapid sequence intubation. Watch for malignant hyperthermia and hyperkalaemia — it is contraindicated in burns or crush injuries after the first 24 hours, and in anyone with a personal or family history of MH. Have dantrolene available wherever it is given.
Mechanism, simply
Succinylcholine binds acetylcholine receptors at the neuromuscular junction and keeps them open. The muscle fibre depolarises and cannot repolarise until the drug clears, so contraction stops and flaccid paralysis follows. This is why you see fasciculations first: a brief wave of visible muscle twitching across the chest and limbs before the patient goes still.
The paralysis is short, usually clearing within 10 minutes, because plasma cholinesterase breaks the drug down quickly. Patients with an inherited cholinesterase deficiency clear it far more slowly, and paralysis can extend to hours. That patient stays intubated and sedated until strength returns; there is no way to reverse the block faster.
Indications you will see on the ward
Rapid sequence intubation is the main use — anaesthesia, the emergency department, or a code where a definitive airway is needed within seconds. Its fast onset (usually under a minute) and short duration make it the preferred agent when you need paralysis now and want it to wear off if intubation fails.
You will also see it for electroconvulsive therapy, to blunt the motor seizure and prevent fracture, and occasionally to relax a patient during laryngospasm that isn't breaking with positioning and oxygen alone.
Assessment before administration
Check serum potassium before the drug goes in if there is any time to do so. Succinylcholine depolarises muscle and releases potassium into the bloodstream, and in a patient who is already hyperkalaemic that can push them into a lethal arrhythmia.
Ask about burns, crush injury, denervation, or major trauma, and check the timeline carefully. In the first 24 hours after a burn or crush injury, succinylcholine is safe. After that window, up-regulated extrajunctional receptors mean the potassium release can be massive, and the drug is contraindicated until the injury has fully healed, which can take months.
Ask about personal or family history of anaesthesia complications, unexplained fever during a prior surgery, or muscle disorders. This screens for malignant hyperthermia susceptibility, which succinylcholine can trigger.
Toxicity and the antidote
There is no reversal agent for succinylcholine itself. Prolonged paralysis from cholinesterase deficiency is managed by keeping the patient sedated and ventilated until the block wears off on its own.
The emergency you are actually watching for is malignant hyperthermia: a hypermetabolic reaction with rising end-tidal CO2, tachycardia, muscle rigidity, and a temperature that can climb rapidly. The treatment is dantrolene, given immediately and repeated per the malignant hyperthermia protocol, along with stopping the triggering agent, cooling measures, and correcting the resulting acidosis and hyperkalaemia. Every OR and any unit that stocks succinylcholine should have a dantrolene kit and a clear protocol posted.
Interactions that matter
Volatile anaesthetics such as sevoflurane and desflurane are also malignant hyperthermia triggers, and the combination is what most MH cases actually occur under. Digoxin toxicity is worsened by the potassium shift succinylcholine causes, so use particular caution in a digitalised patient.
Anticholinesterase drugs, including some used for myasthenia gravis and certain organophosphate exposures, inhibit the plasma cholinesterase that breaks succinylcholine down, prolonging the block. Aminoglycosides and magnesium can potentiate neuromuscular blockade generally, extending recovery time as well.
What the patient must be told
Most patients receiving succinylcholine are intubated and sedated at the time, so teaching happens beforehand for a planned procedure or after the fact for emergency use. Explain that muscle soreness, sometimes significant, is common after the drug wears off, particularly in the jaw, neck, and shoulders, from the fasciculations.
If the patient or a family member reports a personal or family history of a bad reaction to anaesthesia, including unexplained high fever, this needs to go in the record clearly as a malignant hyperthermia flag for every future anaesthetic, not just this one.
The next step on this is the same as on everything else here: answer questions and read the rationales. Our pharmacology practice questions are the closest set to what this page covers.
One question from the pharmacology set
A client with heart failure is started on furosemide 40 mg PO daily. Which findings should the nurse report to the provider before administering the next dose? Select all that apply.
Rationale
Furosemide is a loop diuretic, so the two things you are watching are potassium and kidney function. A potassium of 2.9 mEq/L is below the 3.5–5.0 reference range and puts the client at risk for dysrhythmia — hold and report. Muscle cramps with palpitations are the clinical face of that same hypokalemia, so they are reported together, not separately. A creatinine that doubles signals the diuresis has outrun renal perfusion. A blood pressure of 132/78 and a 1 kg loss are the expected response to the drug working, not reasons to hold it.
Answer: A, D, E
Common questions
Why is succinylcholine contraindicated in burns?
In the first 24 hours after a burn it is fine to use. After that, the body up-regulates extrajunctional acetylcholine receptors on damaged muscle, and succinylcholine causes an exaggerated potassium release from those receptors. This can cause severe, sometimes fatal hyperkalaemia and lasts until the injury heals.
What is the first sign of malignant hyperthermia?
Rising end-tidal CO2 is usually the earliest and most reliable sign, often before temperature climbs. Masseter muscle rigidity after succinylcholine and unexplained tachycardia are also early clues. Fever is a late finding, not the first one.
Is succinylcholine safe in renal failure?
It requires caution rather than an outright contraindication. Baseline potassium should be checked and reviewed with the anaesthesia team, since a patient with renal failure may already be hyperkalaemic before the drug's own potassium release is added.
How long does succinylcholine last?
Typically 5 to 10 minutes in a patient with normal plasma cholinesterase activity. In someone with a genetic cholinesterase deficiency, paralysis can last significantly longer, sometimes several hours, and the patient must be kept sedated and ventilated until it resolves.
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