Jakafi: adverse event reports filed with FDA

55,391

reports as suspect product

0.3% of all reports · about 3,822 a year

4,584

reports, 12 months to June 2026

4,326 in the 12 months before

42.3%

marked serious by the reporter

53.1% across the class

12.6%

record death among outcomes, as reported

6,973 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 Jakafi reports recording the termmedian drug in janus kinase inhibitor

1. Off label useused for a purpose or in a way not on the label22.2%12,310
2. Fatiguetiredness10%5,527
3. Deaththe patient died; cause not stated by this term9.8%5,447
4. Haemoglobin decreasedlow haemoglobin4.4%2,412
5. Anaemialow red blood cells4.2%2,350
6. Dizzinesslight-headedness or unsteadiness4.1%2,256
7. Product dose omission issuea dose was missed4%2,234
8. Diarrhoealoose or frequent stools3.9%2,156
9. Platelet count decreasedlow platelet count3.8%2,129
10. Astheniaweakness or lack of energy3.8%2,102
11. Headachehead pain3.8%2,088
12. Product availability issuethe product was not available3.5%1,911
13. Weight increasedweight gain3.3%1,813
14. Nauseafeeling sick3.2%1,752
15. Dyspnoeashortness of breath3%1,673
16. Painpain, site not specified2.8%1,558
17. Pneumonialung infection2.8%1,538
18. Contusiona bruise2.5%1,406
19. Product dose omissiona dose was missed2.5%1,368
20. Malaisegeneral feeling of being unwell2.5%1,361
21. Falla fall2.4%1,347
22. Platelet count increased2.4%1,326
23. Splenomegaly2.4%1,324
24. Pruritusitching2.4%1,306
25. Drug dose omissiona dose was missed2.2%1,242
26. Arthralgiajoint pain2.1%1,149
27. Blood count abnormal2%1,135
28. White blood cell count increased2%1,131
29. Constipationconstipation1.9%1,057
30. Pain in extremitypain in an arm or leg1.8%1,021

Top 30 of 2,252 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 11 drugs in the janus kinase inhibitor 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 323,323 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. 97.6% 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 55,391 reports.

Drugs most often listed in the same reports

Other products listed in reports where Jakafi is a suspect product, whatever their own role. Co-listing means the two were recorded together; it says nothing about either product's part in the event. Only the 2,500 most-reported names are counted here.

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 janus kinase inhibitor 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 Jakafi as a suspect or interacting product; reports listing it only as a concomitant medication (1,385) 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.