Reported Reactions

Drugs › Kinase inhibitor

Brand name · Ritlecitinib

Litfulo: adverse event reports filed with FDA

1,710 reports list it as a suspect or interacting product, 2023–2026. Class: Kinase inhibitor.

1,710
reports as suspect product
0% of all reports · about 570 a year
568
reports, 12 months to June 2026
687 in the 12 months before
18.1%
marked serious by the reporter
70.8% across the class
0.1%
record death among outcomes, as reported
2 reports · not verified by FDA

1,710 adverse event reports received by FDA list the brand name Litfulo (ritlecitinib) as a suspect or interacting product, from July 2023 to June 2026. A further 28 reports list it only as a concomitant medication, and those are not counted in the figures on this page.

In the 12 months to June 2026, 568 reports listed it, down 17% from 687 in the 12 months before. FDA releases FAERS data quarterly, so the newest months are incomplete and grow in later releases. Over its reporting history that is about 570 reports a year and 0% of the 20,646,523 reports in the database, and 0.2% of the reports for the kinase inhibitor class. How many people take it is not in the data, so a count is not a rate of occurrence.

The MedDRA terms listed most often are drug ineffective (17.8%), therapeutic product effect incomplete (7.4%) and condition aggravated (6.3%). A report can list several reactions, so shares add to more than 100%; 223 different terms appear across these reports. Drug ineffective is recorded in 17.8% of these reports, a larger share than in the median kinase inhibitor drug (2.7%).

18.1% of the reports are marked serious by the reporter (70.8% across the class); 0.1% record death among the outcomes and 3.5% record hospitalisation, as reported. 33.6% of the reports came from physicians, and the largest patient age group is 18 to 44 (28.1%). 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

03876Jul 2021: 0Aug 2021: 0Sep 2021: 0Oct 2021: 0Nov 2021: 0Dec 2021: 02022Jan 2022: 0Feb 2022: 0Mar 2022: 0Apr 2022: 0May 2022: 0Jun 2022: 0Jul 2022: 0Aug 2022: 0Sep 2022: 0Oct 2022: 0Nov 2022: 0Dec 2022: 02023Jan 2023: 0Feb 2023: 0Mar 2023: 0Apr 2023: 0May 2023: 0Jun 2023: 0Jul 2023: 3Aug 2023: 5Sep 2023: 22Oct 2023: 36Nov 2023: 39Dec 2023: 382024Jan 2024: 49Feb 2024: 39Mar 2024: 54Apr 2024: 65May 2024: 42Jun 2024: 63Jul 2024: 51Aug 2024: 68Sep 2024: 64Oct 2024: 65Nov 2024: 49Dec 2024: 532025Jan 2025: 44Feb 2025: 59Mar 2025: 68Apr 2025: 50May 2025: 63Jun 2025: 53Jul 2025: 76Aug 2025: 69Sep 2025: 74Oct 2025: 59Nov 2025: 56Dec 2025: 432026Jan 2026: 25Feb 2026: 32Mar 2026: 31Apr 2026: 36May 2026: 24Jun 2026: 43

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

03577142023: 14320232024: 66220242025: 71420252026: 1912026

2026 covers reports received through June 2026 only.

Reactions recorded in the reports

share of Litfulo reports recording the termmedian drug in kinase inhibitor

  1. Drug ineffectivethe medicine did not work as expected17.8%305
  2. Condition aggravatedthe condition being treated got worse6.3%108
  3. Off label useused for a purpose or in a way not on the label5.1%87
  4. Headachehead pain4.8%82
  5. Diarrhoealoose or frequent stools3.4%58
  6. Alopeciahair loss3%51
  7. Product dose omission issuea dose was missed3%51
  8. Urticariahives2.6%45
  9. Pruritusitching2.6%44
  10. Acneacne2.5%42
  11. Fatiguetiredness2.3%40
  12. Rashskin rash2.2%38
  13. Nauseafeeling sick2%35
  14. Dizzinesslight-headedness or unsteadiness2%34
  15. Illness1.6%28
  16. Alopecia areata1.5%26
  17. Infectionan infection, type not specified1.4%24
  18. Nasopharyngitisa cold1.2%21
  19. Drug hypersensitivityan allergic-type reaction to a medicine1.2%20
  20. Vomitingbeing sick1.2%20
  21. Hepatic enzyme increasedraised liver enzymes1.1%19
  22. Anxietyanxiety1.1%18
  23. Arthralgiajoint pain1.1%18
  24. Covid-19COVID-19 infection1.1%18
  25. Weight increasedweight gain1.1%18
  26. Pain in extremitypain in an arm or leg1%17
  27. Contusiona bruise0.9%16

Top 30 of 223 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 100 drugs in the 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

Death0.1%2
Life-threatening0.4%7
Hospitalisation (initial or prolonged)3.5%59
Disability0.1%2
Congenital anomaly0%0
Other serious15.4%264
Not serious81.9%1,400

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 849,161 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

Patient age

Under 20%0
2 to 110.9%15
12 to 1721.3%365
18 to 4428.1%480
45 to 6416%274
65 to 745.2%89
75 and over1.2%21
Age not given27.3%466

Patient sex

Female58.7%1,003
Male30.2%517
Not given11.1%190

Who reported

Physician33.6%575
Pharmacist2.7%47
Other health professional32%547
Lawyer0%0
Consumer or non-health professional31.6%540
Not given0.1%1

Age and sex as stated in the report; the reporter's qualification is the primary source recorded by FDA. 93.6% of reports give the United States as the country of the event or reporter.

Reason for use recorded

Indication as recorded (MedDRA)ReportsShare
Alopecia areata79246.3%
Alopecia1528.9%
Alopecia universalis382.2%
Alopecia totalis342%
Vitiligo60.4%
Alopecia scarring50.3%

The indication field is filled in by the reporter and is often blank; shares are of all 1,710 reports.

In context

MeasureLitfuloKinase inhibitorAll reports
Reports as suspect product1,710849,16120,646,523
Share of that pool—0.2%0%
Reports, latest 12 months568—1,332,454
Marked serious18.1%70.8%57.4%
Death recorded among outcomes, per 1,000 reports119091
Hospitalisation recorded, per 1,000 reports35264213
Consumer-filed share31.6%42.3%45.8%
Top term, share of reportsDrug ineffective 17.8%median 2.7%6.3%

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 kinase inhibitor class

DrugName typeReportsLatest 12 monthsMarked serious
Ibrancebrand81,9122,38047.1%
Imbruvicabrand67,0392,28374.4%
Cabometyxbrand41,8184,90440.4%
Sutentbrand33,21517574.5%
Afinitorbrand30,70616171.3%
Sprycelbrand27,25555749.7%
Tasignabrand24,91132870.9%
Kisqalibrand24,6033,41379.2%
Ofevbrand23,9072,43466.9%
Gleevecbrand23,1328174.7%
Tagrissobrand23,0851,41092.3%
Lenvimabrand22,3502,64387.3%
Votrientbrand22,08411960.9%
Mekinistbrand17,07091664%
Inlytabrand15,69638860.9%

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.

Questions about Litfulo reports

How many adverse event reports has FDA received for Litfulo?

1,710 reports list Litfulo as a suspect or interacting product in the openFDA FAERS release of 28 Sep 2026, covering reports received through June 2026. 568 of them arrived in the latest 12 months. Another 28 list it only as a concomitant medication.

What reactions are recorded in Litfulo reports?

drug ineffective (17.8%), therapeutic product effect incomplete (7.4%), condition aggravated (6.3%), off label use (5.1%) and headache (4.8%). These are MedDRA preferred terms coded from what the reporter described; a report can list several, and a term's presence is not a finding that Litfulo was responsible.

How serious are the reports?

18.1% are marked serious by the reporter. Among the outcomes recorded, 0.1% of reports include death and 3.5% include hospitalisation. FDA has not verified these outcomes and states that the reports "cannot be used to estimate the incidence" of the events.

Who files these reports?

physician (33.6%), other health professional (32%) and consumer or non-health professional (31.6%). Most reports reach FDA through the manufacturer, which must forward reports it receives.

Are reports for Litfulo rising?

568 reports in the 12 months to June 2026, down 17% from 687 in the 12 months before. FDA releases FAERS data quarterly, so the newest months are incomplete and grow in later releases. Counts also move with how many people take a product, its time on the market and publicity.

Do these reports show that Litfulo was responsible for these reactions?

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." The reaction may relate to the condition being treated, to other medicines, or to something else.

Is this a list of the side effects of Litfulo?

No. It is a count of what was reported to FDA. The adverse reactions observed in clinical studies are printed on the FDA-approved label, which a pharmacist or clinician can go through with you.

How do I report an adverse event?

Consumers and health professionals can report to FDA through MedWatch (Form FDA 3500 online, or 1-800-FDA-1088), or to the manufacturer, which must pass reports on. See the guide on how to report.

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 Litfulo as a suspect or interacting product; reports listing it only as a concomitant medication (28) 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.

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