Reported Reactions

Drugs › Alkylating drug

Generic name

Lomustine: adverse event reports filed with FDA

1,100 reports list it as a suspect or interacting product, 2004–2026. Class: Alkylating drug.

1,100
reports as suspect product
0% of all reports · about 49 a year
92
reports, 12 months to June 2026
56 in the 12 months before
94.8%
marked serious by the reporter
93.5% across the class
26.4%
record death among outcomes, as reported
290 reports · not verified by FDA

Between January 2004 and June 2026, 1,100 adverse event reports received by FDA list lomustine, a generic name as a suspect or interacting product. Reports that mention it only as a concomitant medication (718) are left out of every figure here.

In the 12 months to June 2026, 92 reports listed it, up 64% from 56 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 49 reports a year and 0% of the 20,646,523 reports in the database, and 0.4% of the reports for the alkylating drug 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 thrombocytopenia (12.1%), off label use (9.7%) and neutropenia (8%). A report can list several reactions, so shares add to more than 100%; 337 different terms appear across these reports. Thrombocytopenia is recorded in 12.1% of these reports, a larger share than in the median alkylating drug drug (4%).

94.8% of the reports are marked serious by the reporter (93.5% across the class); 26.4% record death among the outcomes and 28.1% record hospitalisation, as reported. 50.2% of the reports came from other health professionals, and the largest patient age group is 45 to 64 (20.9%). 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

01224Jul 2021: 16Aug 2021: 12Sep 2021: 7Oct 2021: 8Nov 2021: 4Dec 2021: 62022Jan 2022: 9Feb 2022: 6Mar 2022: 2Apr 2022: 19May 2022: 17Jun 2022: 5Jul 2022: 8Aug 2022: 6Sep 2022: 14Oct 2022: 7Nov 2022: 24Dec 2022: 72023Jan 2023: 8Feb 2023: 12Mar 2023: 5Apr 2023: 8May 2023: 1Jun 2023: 5Jul 2023: 14Aug 2023: 18Sep 2023: 6Oct 2023: 10Nov 2023: 11Dec 2023: 72024Jan 2024: 4Feb 2024: 3Mar 2024: 7Apr 2024: 8May 2024: 3Jun 2024: 1Jul 2024: 4Aug 2024: 4Sep 2024: 8Oct 2024: 7Nov 2024: 5Dec 2024: 82025Jan 2025: 4Feb 2025: 2Mar 2025: 1Apr 2025: 6May 2025: 2Jun 2025: 5Jul 2025: 12Aug 2025: 2Sep 2025: 10Oct 2025: 2Nov 2025: 10Dec 2025: 52026Jan 2026: 2Feb 2026: 12Mar 2026: 14Apr 2026: 10May 2026: 11Jun 2026: 2

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

0621242004: 620042005: 42006: 72007: 1720072008: 72009: 122010: 2320102011: 132012: 342013: 1820132014: 472015: 522016: 4620162017: 1022018: 842019: 7620192020: 502021: 992022: 12420222023: 1052024: 622025: 6120252026: 51

2026 covers reports received through June 2026 only.

Reactions recorded in the reports

share of Lomustine reports recording the termmedian drug in alkylating drug

  1. Thrombocytopenialow platelets12.1%133
  2. Off label useused for a purpose or in a way not on the label9.7%107
  3. Neutropenialow neutrophils, a type of white blood cell8%88
  4. Drug ineffectivethe medicine did not work as expected7.5%82
  5. Disease progressionthe disease advanced6.2%68
  6. Fatiguetiredness5.5%61
  7. Anaemialow red blood cells4.3%47
  8. Febrile neutropeniafever with low white blood cells3.8%42
  9. Product use in unapproved indicationused for a purpose not on the label3.6%40
  10. Headachehead pain3.1%34
  11. Nauseafeeling sick3%33
  12. Pneumonialung infection2.8%31
  13. Vomitingbeing sick2.6%29
  14. Sepsisa severe body-wide response to infection2.5%28
  15. Diarrhoealoose or frequent stools2.5%27
  16. Eastern Cooperative Oncology Group performance status worsened2.2%24
  17. Type 2 diabetes mellitustype 2 diabetes2.2%24
  18. Deaththe patient died; cause not stated by this term2.1%23
  19. Pancytopenialow counts of all blood cells2%22
  20. Seizurea fit or convulsion2%22
  21. Toxicity to various agentspoisoning or toxic effect of one or more substances1.9%21
  22. Tumour pseudoprogression1.9%21

Top 30 of 337 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 23 drugs in the alkylating drug 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

Death26.4%290
Life-threatening5.9%65
Hospitalisation (initial or prolonged)28.1%309
Disability1.2%13
Congenital anomaly0.1%1
Other serious63.6%700
Not serious5.2%57

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 253,205 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 21.5%16
2 to 117.4%81
12 to 178.8%97
18 to 4418%198
45 to 6420.9%230
65 to 749.6%106
75 and over2%22
Age not given31.8%350

Patient sex

Female33.4%367
Male44.1%485
Not given22.5%248

Who reported

Physician32.2%354
Pharmacist5.4%59
Other health professional50.2%552
Lawyer0%0
Consumer or non-health professional6.5%71
Not given5.8%64

Age and sex as stated in the report; the reporter's qualification is the primary source recorded by FDA. 25.5% of reports give the United States as the country of the event or reporter.

Reason for use recorded

Indication as recorded (MedDRA)ReportsShare
Glioblastoma14012.7%
Medulloblastoma12511.4%
Glioma504.5%
Hodgkin's disease454.1%
Acute myeloid leukaemia353.2%
Astrocytoma292.6%

The indication field is filled in by the reporter and is often blank; shares are of all 1,100 reports.

Drugs most often listed in the same reports

Drug (any role in the report)ReportsShare of Lomustine reports
Vincristine32629.6%
Procarbazine25122.8%
Temozolomide24121.9%
Etoposide21519.5%
Cisplatin18717%
Cyclophosphamide18717%
Bevacizumab14613.3%
Carboplatin14613.3%
Dexamethasone13212%
Vincristine sulfate12211.1%

Other products listed in reports where Lomustine 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

MeasureLomustineAlkylating drugAll reports
Reports as suspect product1,100253,20520,646,523
Share of that pool—0.4%0%
Reports, latest 12 months92—1,332,454
Marked serious94.8%93.5%57.4%
Death recorded among outcomes, per 1,000 reports26420891
Hospitalisation recorded, per 1,000 reports281333213
Consumer-filed share6.5%6.3%45.8%
Top term, share of reportsThrombocytopenia 12.1%median 4%0.5%

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 alkylating drug class

DrugName typeReportsLatest 12 monthsMarked serious
Cyclophosphamidegeneric141,09912,36097.8%
Ifosfamidegeneric18,6581,32598.2%
Melphalangeneric17,19095698.5%
Temozolomidegeneric15,3241,05582.3%
Busulfangeneric11,8251,09594.9%
Thiotepageneric7,8531,03598.8%
Bendamustine hydrochloridegeneric6,94125396%
Dacarbazinegeneric6,43151196.3%
Temodarbrand4,6522456.1%
Matulanebrand3,84528415.9%
Carmustinegeneric3,37818099%
Treandabrand3,330366.5%
Chlorambucilgeneric2,4867598.5%
Valchlorbrand2,1141628.4%
Mitomycingeneric2,04111792.4%

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 Lomustine reports

How many adverse event reports has FDA received for Lomustine?

1,100 reports list Lomustine as a suspect or interacting product in the openFDA FAERS release of 28 Sep 2026, covering reports received through June 2026. 92 of them arrived in the latest 12 months. Another 718 list it only as a concomitant medication.

What reactions are recorded in Lomustine reports?

thrombocytopenia (12.1%), off label use (9.7%), neutropenia (8%), drug ineffective (7.5%) and disease progression (6.2%). 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 Lomustine was responsible.

How serious are the reports?

94.8% are marked serious by the reporter. Among the outcomes recorded, 26.4% of reports include death and 28.1% 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?

other health professional (50.2%), physician (32.2%) and consumer or non-health professional (6.5%). Most reports reach FDA through the manufacturer, which must forward reports it receives.

Are reports for Lomustine rising?

92 reports in the 12 months to June 2026, up 64% from 56 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 Lomustine 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 Lomustine?

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 Lomustine as a suspect or interacting product; reports listing it only as a concomitant medication (718) 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.