Reported Reactions

Drugs › Alkylating drug

Brand name · Temozolomide

Temodar: adverse event reports filed with FDA

4,652 reports list it as a suspect or interacting product, 2004–2026. Class: Alkylating drug. Also reported as Temodar Capsule.

4,652
reports as suspect product
0% of all reports · about 207 a year
24
reports, 12 months to June 2026
157 in the 12 months before
56.1%
marked serious by the reporter
93.5% across the class
15%
record death among outcomes, as reported
700 reports · not verified by FDA

Between January 2004 and June 2026, 4,652 adverse event reports received by FDA list the brand name Temodar (temozolomide) as a suspect or interacting product. Reports that mention it only as a concomitant medication (694) are left out of every figure here.

In the 12 months to June 2026, 24 reports listed it, down 85% from 157 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 207 reports a year and 0% of the 20,646,523 reports in the database, and 1.8% 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 reactions recorded most often are product use in unapproved indication (18.3%), off label use (8.5%) and nausea (6%). A report can list several reactions, so shares add to more than 100%; 589 different terms appear across these reports. Product use in unapproved indication is recorded in 18.3% of these reports, a larger share than in the median alkylating drug drug (3.3%).

56.1% of the reports are marked serious by the reporter (93.5% across the class); 15% record death among the outcomes and 23.9% record hospitalisation, as reported. 37.5% of the reports came from other health professionals, and the largest patient age group is 45 to 64 (27.8%). 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

04079Jul 2021: 10Aug 2021: 15Sep 2021: 26Oct 2021: 79Nov 2021: 12Dec 2021: 122022Jan 2022: 31Feb 2022: 25Mar 2022: 33Apr 2022: 16May 2022: 22Jun 2022: 10Jul 2022: 16Aug 2022: 28Sep 2022: 37Oct 2022: 30Nov 2022: 33Dec 2022: 102023Jan 2023: 18Feb 2023: 12Mar 2023: 18Apr 2023: 11May 2023: 10Jun 2023: 12Jul 2023: 28Aug 2023: 17Sep 2023: 48Oct 2023: 35Nov 2023: 16Dec 2023: 252024Jan 2024: 18Feb 2024: 35Mar 2024: 17Apr 2024: 31May 2024: 16Jun 2024: 13Jul 2024: 23Aug 2024: 4Sep 2024: 12Oct 2024: 9Nov 2024: 16Dec 2024: 552025Jan 2025: 20Feb 2025: 12Mar 2025: 1Apr 2025: 1May 2025: 2Jun 2025: 2Jul 2025: 1Aug 2025: 1Sep 2025: 2Oct 2025: 2Nov 2025: 6Dec 2025: 22026Jan 2026: 2Feb 2026: 0Mar 2026: 2Apr 2026: 2May 2026: 3Jun 2026: 1

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

01623242004: 9020042005: 1582006: 1872007: 19020072008: 2262009: 1552010: 12720102011: 1322012: 2272013: 28820132014: 2552015: 2262016: 22520162017: 2032018: 2022019: 26220192020: 3242021: 3232022: 29120222023: 2502024: 2492025: 5220252026: 10

2026 covers reports received through June 2026 only.

Reactions recorded in the reports

share of Temodar reports recording the termmedian drug in alkylating drug

  1. Product use in unapproved indicationused for a purpose not on the label18.3%851
  2. Off label useused for a purpose or in a way not on the label8.5%397
  3. Nauseafeeling sick6%280
  4. Deaththe patient died; cause not stated by this term5.7%263
  5. Fatiguetiredness5.6%260
  6. Thrombocytopenialow platelets4.7%217
  7. Vomitingbeing sick4.3%198
  8. Disease progressionthe disease advanced3.9%180
  9. Drug ineffectivethe medicine did not work as expected3.8%178
  10. Product use issuea problem in how the product was used3.2%148
  11. Pancytopenialow counts of all blood cells3%141
  12. Platelet count decreasedlow platelet count3%139
  13. Neutropenialow neutrophils, a type of white blood cell2.8%132
  14. Astheniaweakness or lack of energy2.8%129
  15. Diarrhoealoose or frequent stools2.5%114
  16. Convulsion2.2%104
  17. Pyrexiafever2.2%102
  18. Headachehead pain2.1%99
  19. Pulmonary embolisma blood clot in the lung2%94
  20. Constipationconstipation2%92
  21. Pneumonialung infection1.8%86
  22. Dehydrationdehydration1.8%83
  23. Anaemialow red blood cells1.7%78
  24. Rashskin rash1.6%75
  25. Deep vein thrombosisa blood clot in a deep vein1.6%73
  26. Falla fall1.5%72
  27. Febrile neutropeniafever with low white blood cells1.5%71
  28. No adverse eventno adverse event was reported1.5%71

Top 30 of 589 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

Death15%700
Life-threatening5.1%236
Hospitalisation (initial or prolonged)23.9%1,111
Disability1.7%78
Congenital anomaly0%1
Other serious30.2%1,403
Not serious43.9%2,040

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 20.6%26
2 to 114%186
12 to 172.2%103
18 to 4415%700
45 to 6427.8%1,294
65 to 7411.5%535
75 and over4%186
Age not given34.9%1,622

Patient sex

Female39.4%1,833
Male46.7%2,171
Not given13.9%648

Who reported

Physician31.9%1,486
Pharmacist6.5%303
Other health professional37.5%1,745
Lawyer0%0
Consumer or non-health professional17%790
Not given7.1%328

Age and sex as stated in the report; the reporter's qualification is the primary source recorded by FDA. 96.6% of reports give the United States as the country of the event or reporter.

Reason for use recorded

Indication as recorded (MedDRA)ReportsShare
Glioblastoma multiforme59512.8%
Glioblastoma54811.8%
Brain neoplasm malignant1753.8%
Brain neoplasm1723.7%
Malignant melanoma1132.4%
Glioma992.1%

The indication field is filled in by the reporter and is often blank; shares are of all 4,652 reports.

Drugs most often listed in the same reports

Drug (any role in the report)ReportsShare of Temodar reports
Keppra2886.2%
Decadron2505.4%
Bevacizumab2415.2%
Zofran2034.4%
Capecitabine1743.7%
Dexamethasone1493.2%
Irinotecan hydrochloride1182.5%
Avastin1132.4%
Dilantin1092.3%
Irinotecan1052.3%

Other products listed in reports where Temodar 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

MeasureTemodarAlkylating drugAll reports
Reports as suspect product4,652253,20520,646,523
Share of that pool—1.8%0%
Reports, latest 12 months24—1,332,454
Marked serious56.1%93.5%57.4%
Death recorded among outcomes, per 1,000 reports15020891
Hospitalisation recorded, per 1,000 reports239333213
Consumer-filed share17%6.3%45.8%
Top term, share of reportsProduct use in unapproved indication 18.3%median 3.3%1.2%

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%
Matulanebrand3,84528415.9%
Carmustinegeneric3,37818099%
Treandabrand3,330366.5%
Chlorambucilgeneric2,4867598.5%
Valchlorbrand2,1141628.4%
Mitomycingeneric2,04111792.4%
Lomustinegeneric1,1009294.8%

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 Temodar reports

How many adverse event reports has FDA received for Temodar?

4,652 reports list Temodar as a suspect or interacting product in the openFDA FAERS release of 28 Sep 2026, covering reports received through June 2026. 24 of them arrived in the latest 12 months. Another 694 list it only as a concomitant medication.

What reactions are recorded in Temodar reports?

product use in unapproved indication (18.3%), off label use (8.5%), nausea (6%), death (5.7%) and fatigue (5.6%). 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 Temodar was responsible.

How serious are the reports?

56.1% are marked serious by the reporter. Among the outcomes recorded, 15% of reports include death and 23.9% 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 (37.5%), physician (31.9%) and consumer or non-health professional (17%). Most reports reach FDA through the manufacturer, which must forward reports it receives.

Are reports for Temodar rising?

24 reports in the 12 months to June 2026, down 85% from 157 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 Temodar 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 Temodar?

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 Temodar as a suspect or interacting product; reports listing it only as a concomitant medication (694) 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.