Reported Reactions

Drugs › Alkylating drug

Brand name · Mechlorethamine hydrochloride

Valchlor: adverse event reports filed with FDA

2,114 reports list it as a suspect or interacting product, 2014–2026. Class: Alkylating drug.

2,114
reports as suspect product
0% of all reports · about 171 a year
16
reports, 12 months to June 2026
24 in the 12 months before
28.4%
marked serious by the reporter
93.5% across the class
5.8%
record death among outcomes, as reported
122 reports · not verified by FDA

2,114 adverse event reports received by FDA list the brand name Valchlor (mechlorethamine hydrochloride) as a suspect or interacting product, from March 2014 to June 2026. A further 29 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, 16 reports listed it, down 33% from 24 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 171 reports a year and 0% of the 20,646,523 reports in the database, and 0.8% 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.

Reporters most often recorded pruritus (14.4%), application site pruritus (10.2%) and application site pain (10%). A report can list several reactions, so shares add to more than 100%; 278 different terms appear across these reports. Pruritus is recorded in 14.4% of these reports, a larger share than in the median alkylating drug drug (0.2%).

28.4% of the reports are marked serious by the reporter (93.5% across the class); 5.8% record death among the outcomes and 10.5% record hospitalisation, as reported. 44.8% of the reports came from physicians, and the largest patient age group is 45 to 64 (23.7%). 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

0612Jul 2021: 4Aug 2021: 2Sep 2021: 2Oct 2021: 6Nov 2021: 5Dec 2021: 62022Jan 2022: 5Feb 2022: 4Mar 2022: 12Apr 2022: 2May 2022: 6Jun 2022: 5Jul 2022: 9Aug 2022: 2Sep 2022: 2Oct 2022: 3Nov 2022: 2Dec 2022: 52023Jan 2023: 2Feb 2023: 1Mar 2023: 3Apr 2023: 3May 2023: 5Jun 2023: 2Jul 2023: 1Aug 2023: 2Sep 2023: 4Oct 2023: 0Nov 2023: 2Dec 2023: 12024Jan 2024: 2Feb 2024: 1Mar 2024: 1Apr 2024: 3May 2024: 2Jun 2024: 2Jul 2024: 5Aug 2024: 4Sep 2024: 3Oct 2024: 2Nov 2024: 1Dec 2024: 12025Jan 2025: 1Feb 2025: 3Mar 2025: 0Apr 2025: 4May 2025: 0Jun 2025: 0Jul 2025: 2Aug 2025: 0Sep 2025: 2Oct 2025: 2Nov 2025: 3Dec 2025: 12026Jan 2026: 0Feb 2026: 1Mar 2026: 2Apr 2026: 0May 2026: 1Jun 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

02194372014: 2820142015: 2532016: 43720162017: 3842018: 25220182019: 2672020: 30020202021: 592022: 5720222023: 262024: 2720242025: 182026: 62026

2026 covers reports received through June 2026 only.

Reactions recorded in the reports

share of Valchlor reports recording the termmedian drug in alkylating drug

  1. Pruritusitching14.4%305
  2. Application site pruritusitching where the product was applied10.2%215
  3. Application site erythemaredness where the product was applied10%211
  4. Erythemaskin redness9.6%202
  5. Condition aggravatedthe condition being treated got worse8.7%184
  6. Off label useused for a purpose or in a way not on the label7%149
  7. Skin discolourationa change in skin colour6.8%143
  8. Rashskin rash6%126
  9. Skin irritationirritated skin5%106
  10. Blistera blister4.7%100
  11. Application site discolouration4.6%97
  12. Dry skindry skin4.3%91
  13. Disease progressionthe disease advanced4.2%88
  14. Drug ineffectivethe medicine did not work as expected4.1%87
  15. Deaththe patient died; cause not stated by this term3.9%83
  16. Skin burning sensationburning skin3.8%81
  17. Therapy non-responderthe treatment did not work3.4%72
  18. Skin exfoliationpeeling skin2.9%62
  19. Painpain, site not specified2.3%48
  20. Fatiguetiredness2.2%47
  21. Application site discharge2%42
  22. Application site exfoliation2%42

Top 30 of 278 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

Death5.8%122
Life-threatening0.3%7
Hospitalisation (initial or prolonged)10.5%221
Disability0.8%17
Congenital anomaly0%0
Other serious17.4%367
Not serious71.6%1,513

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%0
2 to 110%1
12 to 170%0
18 to 446.4%136
45 to 6423.7%501
65 to 7420.1%425
75 and over20%423
Age not given29.7%628

Patient sex

Female47%993
Male52.8%1,116
Not given0.2%5

Who reported

Physician44.8%948
Pharmacist0.6%12
Other health professional21.4%453
Lawyer0%0
Consumer or non-health professional33%698
Not given0.1%3

Age and sex as stated in the report; the reporter's qualification is the primary source recorded by FDA. 98.8% of reports give the United States as the country of the event or reporter.

Reason for use recorded

Indication as recorded (MedDRA)ReportsShare
Mycosis fungoides1,28460.7%
Cutaneous t-cell lymphoma64330.4%
Mycosis fungoides stage i60.3%
Cutaneous t-cell lymphoma stage i30.1%
Accidental exposure to product20.1%
Cutaneous t-cell lymphoma stage ii20.1%

The indication field is filled in by the reporter and is often blank; shares are of all 2,114 reports.

Drugs most often listed in the same reports

Drug (any role in the report)ReportsShare of Valchlor reports
Clobetasol1477%
Aspirin1255.9%
Ergocalciferol914.3%
Triamcinolone acetonide914.3%
Triamcinolone733.5%
Lisinopril673.2%
Synthroid602.8%
Lipitor572.7%
Folic acid422%
Levothyroxine422%

Other products listed in reports where Valchlor 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

MeasureValchlorAlkylating drugAll reports
Reports as suspect product2,114253,20520,646,523
Share of that pool—0.8%0%
Reports, latest 12 months16—1,332,454
Marked serious28.4%93.5%57.4%
Death recorded among outcomes, per 1,000 reports5820891
Hospitalisation recorded, per 1,000 reports105333213
Consumer-filed share33%6.3%45.8%
Top term, share of reportsPruritus 14.4%median 0.2%1.8%

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%
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 Valchlor reports

How many adverse event reports has FDA received for Valchlor?

2,114 reports list Valchlor as a suspect or interacting product in the openFDA FAERS release of 28 Sep 2026, covering reports received through June 2026. 16 of them arrived in the latest 12 months. Another 29 list it only as a concomitant medication.

What reactions are recorded in Valchlor reports?

pruritus (14.4%), application site pruritus (10.2%), application site pain (10%), application site erythema (10%) and erythema (9.6%). 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 Valchlor was responsible.

How serious are the reports?

28.4% are marked serious by the reporter. Among the outcomes recorded, 5.8% of reports include death and 10.5% 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 (44.8%), consumer or non-health professional (33%) and other health professional (21.4%). Most reports reach FDA through the manufacturer, which must forward reports it receives.

Are reports for Valchlor rising?

16 reports in the 12 months to June 2026, down 33% from 24 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 Valchlor 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 Valchlor?

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 Valchlor as a suspect or interacting product; reports listing it only as a concomitant medication (29) 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.