Zanaflex: adverse event reports filed with FDA

1,166

reports as suspect product

0% of all reports · about 52 a year

10

reports, 12 months to June 2026

19 in the 12 months before

54.5%

marked serious by the reporter

75.5% across the class

3.1%

record death among outcomes, as reported

36 reports · not verified by FDA

Reports by month, five years

Reports by the month FDA received them. FDA releases FAERS data quarterly, so the newest months are incomplete and grow in later releases.

By year received

2026 covers reports received through June 2026 only.

Reactions recorded in the reports

share of Zanaflex reports recording the termmedian drug in central alpha-2 adrenergic agonist

1. Drug hypersensitivityan allergic-type reaction to a medicine10.5%123
2. Falla fall8.9%104
3. Drug ineffectivethe medicine did not work as expected8.7%102
4. Dizzinesslight-headedness or unsteadiness7.3%85
5. Fatiguetiredness6.9%80
6. Muscle spasmsmuscle cramps6.5%76
7. Gait disturbancedifficulty walking6.1%71
8. Painpain, site not specified6.1%71
9. Somnolencedrowsiness6%70
10. Nauseafeeling sick5.9%69
11. Astheniaweakness or lack of energy5.8%68
12. Headachehead pain5.3%62
13. Memory impairmentmemory problems5.1%60
14. Confusional stateconfusion4.5%52
15. Depressionlow mood4.5%52
16. Urinary tract infectionbladder or urinary infection4.3%50
17. Insomniadifficulty sleeping4.1%48
18. Arthralgiajoint pain3.7%43
19. Condition aggravatedthe condition being treated got worse3.7%43
20. Feeling abnormalfeeling odd or not right3.7%43
21. Drug interactionan interaction between medicines3.6%42
22. Loss of consciousnesspassing out3.6%42
23. Back painback pain3.3%38
24. Multiple sclerosis relapsea flare of multiple sclerosis3.2%37
25. Therapy cessation3.2%37
26. Off label useused for a purpose or in a way not on the label3%35
27. Hypoaesthesianumbness2.9%34
28. Tremorshaking2.9%34
29. Balance disorderproblems with balance2.8%33
30. Hypotensionlow blood pressure2.8%33

Top 30 of 447 MedDRA preferred terms recorded across these reports, with a plain-language gloss where one is available. One report can record several terms. The hollow bar is the median share across the 13 drugs in the central alpha-2 adrenergic agonist class; it describes the reports, not the patients. 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."

Outcomes recorded

Outcome flags as the reporter set them; a report can carry several, and "other serious" is FDA's own category for serious reports outside the named outcomes. Grey bar: all 31,745 reports in the class. FDA has not verified any outcome and states that the reports "cannot be used to estimate the incidence of these events."

Patients and reporters

Age and sex as stated in the report; the reporter's qualification is the primary source recorded by FDA. 92% of reports give the United States as the country of the event or reporter.

Reason for use recorded

The indication field is filled in by the reporter and is often blank; shares are of all 1,166 reports.

In context

Shares are of reports, not of patients treated. The number of people taking a product is not in the data, so none of these figures is a rate, and differences between columns reflect who takes a product, who reports and how long it has been sold. 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."

Other drugs in the central alpha-2 adrenergic agonist class

Ordered by report count for navigation only. 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." A brand and its generic are separate rows because reporters name them separately.

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. A report counts here when it lists Zanaflex as a suspect or interacting product; reports listing it only as a concomitant medication (10,140) are excluded. 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.