Alemtuzumab: adverse event reports filed with FDA

8,610

reports as suspect product

0% of all reports · about 384 a year

426

reports, 12 months to June 2026

376 in the 12 months before

95.8%

marked serious by the reporter

86% across the class

15.3%

record death among outcomes, as reported

1,321 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 Alemtuzumab reports recording the termmedian drug in cd52-directed cytolytic antibody

1. Off label useused for a purpose or in a way not on the label13.7%1,176
2. Headachehead pain13.1%1,130
3. Fatiguetiredness12.3%1,060
4. Pyrexiafever10.9%940
5. Nauseafeeling sick8.9%766
6. Lymphocyte count decreased7.8%674
7. Rashskin rash7.4%636
8. Drug ineffectivethe medicine did not work as expected7.1%615
9. Dyspnoeashortness of breath6.4%548
10. Astheniaweakness or lack of energy6.3%541
11. Cytomegalovirus infection6.1%527
12. Multiple sclerosis relapsea flare of multiple sclerosis5.9%506
13. Urinary tract infectionbladder or urinary infection5.9%505
14. Dizzinesslight-headedness or unsteadiness5.2%449
15. White blood cell count decreasedlow white cell count5.1%438
16. Painpain, site not specified5%429
17. Insomniadifficulty sleeping4.9%422
18. Condition aggravatedthe condition being treated got worse4.9%421
19. Coughcough4.6%399
20. Product use in unapproved indicationused for a purpose not on the label4.6%392
21. Vomitingbeing sick4.5%390
22. Pruritusitching4.5%384
23. Malaisegeneral feeling of being unwell4.4%383
24. Diarrhoealoose or frequent stools4.4%381
25. Gait disturbancedifficulty walking4.3%368
26. Platelet count decreasedlow platelet count4.3%366
27. Muscular weaknessmuscle weakness4.2%364
28. Urine abnormality4.2%362
29. Hypoaesthesianumbness4.2%359
30. Pneumonialung infection4.1%355

Top 30 of 1,974 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 3 drugs in the cd52-directed cytolytic antibody 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 17,330 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. 35.6% 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 8,610 reports.

Drugs most often listed in the same reports

Other products listed in reports where Alemtuzumab 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 cd52-directed cytolytic antibody 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 Alemtuzumab as a suspect or interacting product; reports listing it only as a concomitant medication (1,437) 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.