MedDRA preferred term

Muscle rigidity: adverse event reports recording this term

11,747 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.

11,747
reports recording the term: 0.1% of all reports; 647
reports, 12 months to June 2026: 635 in the 12 months before; 88.8%
marked serious by the reporter: 57.4% across all reports; 6.7%
record death among outcomes, as reported: 9.1% across all reports

"Muscle rigidity" is a MedDRA preferred term recorded in 11,747 adverse event reports received by FDA, 0.1% of the database, from January 2004 to June 2026. The term is chosen by whoever codes the report to match what the reporter described.

647 reports recorded it in the 12 months to June 2026, close to the 635 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, 88.8% are marked serious, 6.7% include death among the outcomes and 47.8% include hospitalisation, as reported.

The drugs listed most often as suspect products in those reports are Carbidopa levodopa, Risperidone and Olanzapine. 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
Carbidopa levodopa	Aromatic amino acid	1,102	5.5%
Risperidone	Atypical antipsychotic	558	1.2%
Olanzapine	Atypical antipsychotic	536	1.1%
Quetiapine	Atypical antipsychotic	536	1%
Duodopa	—	451	2.6%
Haloperidol	Typical antipsychotic	340	2.4%
Aripiprazole	Atypical antipsychotic	285	0.9%
Clozapine	Atypical antipsychotic	261	0.4%
Abilify	Atypical antipsychotic	252	0.5%
Sertraline	Serotonin reuptake inhibitor	239	0.5%
Mirtazapine	—	225	0.7%
Fentanyl	Opioid agonist	201	0.4%
Lorazepam	Benzodiazepine	188	0.6%
Citalopram	Serotonin reuptake inhibitor	186	0.6%
Diazepam	Benzodiazepine	184	0.5%
Risperdal	Atypical antipsychotic	183	0.3%
Clonazepam	Benzodiazepine	178	0.5%
Seroquel	Atypical antipsychotic	168	0.3%
Escitalopram	Serotonin reuptake inhibitor	165	0.7%
Fluoxetine	Serotonin reuptake inhibitor	165	0.6%
Quetiapine fumarate	Atypical antipsychotic	161	0.8%
Zyprexa	Atypical antipsychotic	161	0.6%
Lamotrigine	Anti-epileptic agent	157	0.4%
Omeprazole	Proton pump inhibitor	154	0.3%
Baclofen	gamma-Aminobutyric acid-ergic agonist	142	0.7%

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	3,703	0.5%	0.3%
Aromatic amino acid	1,401	2.7%	1.7%
Serotonin reuptake inhibitor	1,313	0.5%	0.3%
Benzodiazepine	787	0.3%	0.2%
Anti-epileptic agent	589	0.2%	0.1%
Opioid agonist	511	0.1%	0%
Serotonin and norepinephrine reuptake inhibitor	384	0.2%	0.2%
Typical antipsychotic	367	2.2%	1.5%
Nonsteroidal anti-inflammatory drug	310	0.1%	0%
Mood stabilizer	296	0.5%	0.7%

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 21%121

2 to 112.2%254

12 to 173.1%362

18 to 4418.4%2,167

45 to 6422.2%2,606

65 to 7414.1%1,655

75 and over13%1,523

Age not given26%3,059

Patient sex

Female48.6%5,713

Male44.4%5,213

Not given7%821

Grey bar: all 20,646,523 reports in the database. 33.6% of these reports give the United States as the country.

Questions about "Muscle rigidity"

What does "Muscle rigidity" mean in an adverse event report?

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 muscle rigidity?

11,747 reports through June 2026 (0.1% of all reports), 647 of them in the latest 12 months.

Which drugs appear most often in these reports?

Carbidopa levodopa (1,102), Risperidone (558), Olanzapine (536), Quetiapine (536) and Duodopa (451). 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.