Neuroleptic Malignant Syndrome – also known as NMS is a disorder that affects the neurological system and can be life threatening. It is most often seen as an adverse reaction to medications especially neuroleptic or antipsychotic drugs.

It is categorized as muscle rigidity, fever, altered mental status, and autonomic dysfunction.

It should be the first consideration in a patient with mental status changes and a fever, though other things could be a cause such as heat stroke, CNS infections, agitated delirium, status epilepticus, and other extrapyramidal symptoms, and more.

The method of action begins in the brain where Dopaminergic receptors are believed to be blocked. It can result in a change of the Skeletal Muscle causing an increased in heat generation. Additionally, it causes the individual to have difficulty with regulation of their own temperature.

When the dosing of a medicaiton is increased – this can also increase the risks of developing NMS.

It is rare and is believed to occurs in approximately 0.2% of those taking the above mentioned medications.

Without Treatment – death is a possibility. This means that it can be an emergency.

Typical Symptoms Seen

–  Muscle rigidity – *** usually one of the first symptoms
–  Fever – *** usually one of the first symptoms
–  Change in blood pressure
–  Mental status changes
–  Confusion
–  Tremors of muscle
–  Visual changes

Medications That Can Cause Neuroleptic Malignant Syndrome:


1.)  Haloperidol
2.)  Fluphenazine
3.)  Chlorpromazine
4.)  Prochlorperazine
5.)  Trifuoperazine
6.)  Thioridazine
7.)  Thiothixene
8.)  Loxapine
9.)  Perphenazine
10.)  Bromperidol
11.)  Clopenthixol
12.)  Promazine

1.)  Clozapine
2.)  Risperidone
3.)  Olanzapine
4.)  Quetiapine
5.)  Ziprasidone
6.)  Aripiprazole

Nonneuroleptics with Antidopaminergic Activity

1.)  Metoclopromide
2.)  Tetrabenazine
3.)  Reserpine
4.)  Droperidol
5.)  Promethazine
6.)  Amoxapine
7.)  Diatrizoate

1.)  Levodopa
2.)  Dopamine agonists
3.)  Amantadine
4.)  Tolcapone

1.)  Lithium
2.)  Phenelzine
3.)  Dosulepin
4.)  Desipramine
5.)  Trimipramine

Mnemonic – FEVER – Help with Diagnosis

F – Fever
E – Encephalopathy
V – Vitals unstable
E – Elevated Enzymes (CPK elevation)
R –  Rigidity of muscles


–  This is an emergent medical situation
–  Death is possible without treatment
–  Medication must be stopped initially
–  Hospital visit
–  Hydration
–  Treat for fever
–  Ice packs
–  Placement in groin, under arms, and chest region
–  Possible need for ventilation


.  Dantrolene sodium
.  Bromocriptine
.  Apomorphine
.  Benzodiazepines

*** – in some cases when the drug causing this condition is restarted – a recurrence of symptoms may occur – but for the most part it does not.