MedDRA preferred term · a rare severe reaction with fever and rigidity

Neuroleptic malignant syndrome: adverse event reports recording this term

11,678 reports to FDA record it, 2004–2026; 0.1% of the database.

Read first · FDA's statement on these data

Adverse event reports submitted to FDA do not undergo extensive validation or verification. Therefore, a causal relationship cannot be established between product and reactions listed in a report. While a suspected relationship may exist, it is not medically validated and should not be the sole source of information for clinical decision making or other assumptions about the safety or efficacy of a product. Additionally, it is important to remember that adverse event reports represent a small percentage of total usage numbers of a product. Common products may have a higher number of adverse events due to the higher total number of people using the product. openFDA, FDA

FDA adds: "There is no certainty that the reported event (adverse event or medication error) was actually due to the product. FDA does not require that a causal relationship between a product and event be proven, and reports do not always contain enough detail to properly evaluate an event." The information in these reports "cannot be used to estimate the incidence of these events."

Do not rely on openFDA to make decisions regarding medical care. While we make every effort to ensure that data is accurate, you should assume all results are unvalidated.

Not medical advice. This site counts what was reported to FDA. Questions about a medicine or device belong with a pharmacist or clinician.

11,678
reports recording the term: 0.1% of all reports; 643
reports, 12 months to June 2026: 676 in the 12 months before; 99.4%
marked serious by the reporter: 57.4% across all reports; 12.5%
record death among outcomes, as reported: 9.1% across all reports

11,678 reports in FDA's adverse event database record the MedDRA term "Neuroleptic malignant syndrome" (in plain words, a rare severe reaction with fever and rigidity): 0.1% of all reports received between January 2004 and June 2026. Coders pick the term that best matches the reporter's description.

643 reports recorded it in the 12 months to June 2026, close to the 676 of the 12 months before. FDA releases FAERS data quarterly, so the newest months are incomplete and grow in later releases. Of reports recording this term, 99.4% are marked serious, 12.5% include death among the outcomes and 67.6% include hospitalisation, as reported.

The drugs listed most often as suspect products in those reports are Olanzapine, Haloperidol and Quetiapine. That order mostly follows how many reports each drug has overall; the table also gives the term's share within each drug's own reports. FDA states that "a causal relationship cannot be established between product and reactions listed in a report" and that for any given report "there is no certainty that a suspected drug caused the event."

Reports by month, five years

FDA releases FAERS data quarterly, so the newest months are incomplete and grow in later releases.

Drugs listed as suspect products in these reports

Drug	Class	Reports with this term	Share of the drug's own reports
Olanzapine	Atypical antipsychotic	1,971	4.2%
Haloperidol	Typical antipsychotic	1,508	10.6%
Quetiapine	Atypical antipsychotic	1,483	2.8%
Risperidone	Atypical antipsychotic	1,438	3.2%
Clozapine	Atypical antipsychotic	881	1.2%
Aripiprazole	Atypical antipsychotic	866	2.9%
Abilify	Atypical antipsychotic	671	1.2%
Seroquel	Atypical antipsychotic	610	1.2%
Lorazepam	Benzodiazepine	550	1.7%
Risperdal	Atypical antipsychotic	519	1%
Zyprexa	Atypical antipsychotic	498	1.9%
Quetiapine fumarate	Atypical antipsychotic	435	2.2%
Lithium	Mood stabilizer	412	3.8%
Mirtazapine	—	357	1.1%
Valproic acid	Anti-epileptic agent	349	1.6%
Diazepam	Benzodiazepine	344	0.9%
Clozaril	Atypical antipsychotic	339	0.7%
Sertraline	Serotonin reuptake inhibitor	325	0.7%
Clonazepam	Benzodiazepine	322	0.9%
Haldol	—	249	2.8%
Lithium carbonate	Mood stabilizer	238	3.3%
Paroxetine	Serotonin reuptake inhibitor	223	1.4%
Chlorpromazine	Phenothiazine	212	6.3%
Lamotrigine	Anti-epileptic agent	205	0.5%
Amisulpride	Dopamine-2 receptor antagonist	203	5.8%

Drugs with a page on this site, ordered by the number of their reports recording this term. The last column is the term's share within that drug's own reports, against 0.1% across the whole database. FDA states that adverse event reports "represent a small percentage of total usage numbers of a product", that "common products may have a higher number of adverse events due to the higher total number of people using the product", and that the data "by themselves are not an indicator of the safety profile of the drug or biologic."

By pharmacologic class

Class	Reports with this term	Share of class reports	Median drug in class
Atypical antipsychotic	10,836	1.6%	1.2%
Typical antipsychotic	1,605	9.8%	6.7%
Benzodiazepine	1,479	0.6%	0%
Serotonin reuptake inhibitor	1,391	0.5%	0.4%
Anti-epileptic agent	1,063	0.4%	0.2%
Mood stabilizer	813	1.4%	1.9%
Serotonin and norepinephrine reuptake inhibitor	449	0.3%	0.1%
Phenothiazine	421	2.7%	1.4%
Dopamine-2 receptor antagonist	376	0.9%	0.5%
Aromatic amino acid	206	0.4%	0.4%

Classes ordered by count. Class shares follow the class's overall report volume as much as anything else.

Patients in these reports

Patient age

Under 20.2%26

2 to 111%114

12 to 175.1%595

18 to 4429.4%3,436

45 to 6426.5%3,099

65 to 7410.1%1,185

75 and over7.3%856

Age not given20.3%2,367

Patient sex

Female36.1%4,218

Male54.4%6,356

Not given9.5%1,104

Grey bar: all 20,646,523 reports in the database. 28.5% of these reports give the United States as the country.

Questions about "Neuroleptic malignant syndrome"

What does "Neuroleptic malignant syndrome" mean in an adverse event report?

In plain language: a rare severe reaction with fever and rigidity. It is a MedDRA preferred term, the dictionary FDA uses to code what a reporter described. The report's own description is not published by openFDA and is not shown here.

How many reports record neuroleptic malignant syndrome?

11,678 reports through June 2026 (0.1% of all reports), 643 of them in the latest 12 months.

Which drugs appear most often in these reports?

Olanzapine (1,971), Haloperidol (1,508), Quetiapine (1,483), Risperidone (1,438) and Clozapine (881). Drugs with many reports overall lead almost every term's list. FDA states that adverse event reports "represent a small percentage of total usage numbers of a product", that "common products may have a higher number of adverse events due to the higher total number of people using the product", and that the data "by themselves are not an indicator of the safety profile of the drug or biologic."

Does a drug appearing here mean it was responsible for this reaction?

No. FDA states that "a causal relationship cannot be established between product and reactions listed in a report" and that for any given report "there is no certainty that a suspected drug caused the event."

I have this symptom. What should I do?

This site cannot assess anyone. A pharmacist or clinician can; for an emergency, call the local emergency number. Nothing on this page is medical advice.

Where this comes from. Counts are built from the openFDA Drug Adverse Event (FAERS) bulk export released 28 Sep 2026, which holds reports FDA received through 30 Jun 2026. Drug names are as reported, resolved to the brand or generic name on the FDA label where openFDA's harmonisation matched them; classes are the pharmacologic class (EPC) from the label and the National Drug Code Directory of 17 Sep 2026. Terms are pooled across spelling and capitalisation variants of one MedDRA preferred term. No report narrative, lot number, patient detail or reporter identity is published. See the methodology and sources; FDA's record is authoritative, and corrections are handled within five working days.

Drug data (FAERS) through 30 Jun 2026; device data (MAUDE) through 31 Aug 2026. Not medical advice.