MedDRA preferred term

Haemophagocytic lymphohistiocytosis: adverse event reports recording this term

7,130 reports to FDA record it, 2008–2026; 0% of the database.

Read first · FDA's statement on these data

Adverse event reports submitted to FDA do not undergo extensive validation or verification. Therefore, a causal relationship cannot be established between product and reactions listed in a report. While a suspected relationship may exist, it is not medically validated and should not be the sole source of information for clinical decision making or other assumptions about the safety or efficacy of a product. Additionally, it is important to remember that adverse event reports represent a small percentage of total usage numbers of a product. Common products may have a higher number of adverse events due to the higher total number of people using the product. openFDA, FDA

FDA adds: "There is no certainty that the reported event (adverse event or medication error) was actually due to the product. FDA does not require that a causal relationship between a product and event be proven, and reports do not always contain enough detail to properly evaluate an event." The information in these reports "cannot be used to estimate the incidence of these events."

Do not rely on openFDA to make decisions regarding medical care. While we make every effort to ensure that data is accurate, you should assume all results are unvalidated.

Not medical advice. This site counts what was reported to FDA. Questions about a medicine or device belong with a pharmacist or clinician.

7,130
reports recording the term: 0% of all reports; 1,119
reports, 12 months to June 2026: 1,127 in the 12 months before; 99.8%
marked serious by the reporter: 57.4% across all reports; 31.5%
record death among outcomes, as reported: 9.1% across all reports

"Haemophagocytic lymphohistiocytosis" is a MedDRA preferred term recorded in 7,130 adverse event reports received by FDA, 0% of the database, from May 2008 to June 2026. The term is chosen by whoever codes the report to match what the reporter described.

1,119 reports recorded it in the 12 months to June 2026, close to the 1,127 of the 12 months before. FDA releases FAERS data quarterly, so the newest months are incomplete and grow in later releases. Of reports recording this term, 99.8% are marked serious, 31.5% include death among the outcomes and 61.1% include hospitalisation, as reported.

The drugs listed most often as suspect products in those reports are Prednisone, Tacrolimus and Cyclophosphamide. That order mostly follows how many reports each drug has overall; the table also gives the term's share within each drug's own reports. 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

FDA releases FAERS data quarterly, so the newest months are incomplete and grow in later releases.

Drugs listed as suspect products in these reports

Drug	Class	Reports with this term	Share of the drug's own reports
Prednisone	Corticosteroid	743	0.4%
Tacrolimus	Calcineurin inhibitor immunosuppressant	651	0.7%
Cyclophosphamide	Alkylating drug	571	0.4%
Methotrexate	Folate analog metabolic inhibitor	554	0.3%
Mycophenolate mofetil	Antimetabolite immunosuppressant	536	0.7%
Dexamethasone	Corticosteroid	531	0.4%
Methylprednisolone	Corticosteroid	486	1%
Etoposide	Topoisomerase inhibitor	451	0.7%
Prednisolone	Corticosteroid	442	0.5%
Rituximab	CD20-directed cytolytic antibody	424	0.3%
Cyclosporine	Calcineurin inhibitor immunosuppressant	420	1.1%
Anakinra	Interleukin-1 receptor antagonist	352	6.2%
Lamotrigine	Anti-epileptic agent	316	0.7%
Tocilizumab	Interleukin-6 receptor antagonist	278	1.1%
Fludarabine	Nucleoside metabolic inhibitor	235	1.2%
Keytruda	Programmed death Receptor-1 blocking antibody	230	0.4%
Carboplatin	Platinum-based drug	229	0.2%
Adalimumab	Tumor necrosis factor blocker	219	0.6%
Azathioprine	Purine antimetabolite	193	0.6%
Infliximab	Tumor necrosis factor blocker	193	0.4%
Pembrolizumab	Programmed death Receptor-1 blocking antibody	172	0.6%
Cytarabine	Nucleoside metabolic inhibitor	171	0.3%
Mycophenolic acid	Antimetabolite immunosuppressant	168	1.2%
Doxorubicin	Anthracycline topoisomerase inhibitor	165	0.3%
Vincristine	—	148	0.2%

Drugs with a page on this site, ordered by the number of their reports recording this term. The last column is the term's share within that drug's own reports, against 0% across the whole database. 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."

By pharmacologic class

Class	Reports with this term	Share of class reports	Median drug in class
Corticosteroid	2,325	0.3%	0%
Calcineurin inhibitor immunosuppressant	1,130	0.5%	0.1%
Alkylating drug	896	0.4%	0%
Programmed death Receptor-1 blocking antibody	784	0.3%	0.3%
Antimetabolite immunosuppressant	748	0.6%	0.5%
Folate analog metabolic inhibitor	722	0.2%	0.1%
Nucleoside metabolic inhibitor	644	0.2%	0.1%
Tumor necrosis factor blocker	535	0.1%	0%
Interleukin-1 receptor antagonist	492	3.5%	3.9%
Anti-epileptic agent	485	0.2%	0%

Classes ordered by count. Class shares follow the class's overall report volume as much as anything else.

Patients in these reports

Patient age

Under 22.2%159

2 to 118.9%632

12 to 175%356

18 to 4421.9%1,558

45 to 6423%1,643

65 to 7414.2%1,016

75 and over5.7%405

Age not given19.1%1,361

Patient sex

Female42.1%3,001

Male44.4%3,169

Not given13.5%960

Grey bar: all 20,646,523 reports in the database. 29.5% of these reports give the United States as the country.

Questions about "Haemophagocytic lymphohistiocytosis"

What does "Haemophagocytic lymphohistiocytosis" mean in an adverse event report?

It is a MedDRA preferred term, the dictionary FDA uses to code what a reporter described. The report's own description is not published by openFDA and is not shown here.

How many reports record haemophagocytic lymphohistiocytosis?

7,130 reports through June 2026 (0% of all reports), 1,119 of them in the latest 12 months.

Which drugs appear most often in these reports?

Prednisone (743), Tacrolimus (651), Cyclophosphamide (571), Methotrexate (554) and Mycophenolate mofetil (536). Drugs with many reports overall lead almost every term's list. 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."

Does a drug appearing here mean it was responsible for this reaction?

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."

I have this symptom. What should I do?

This site cannot assess anyone. A pharmacist or clinician can; for an emergency, call the local emergency number. Nothing on this page is medical advice.

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. Terms are pooled across spelling and capitalisation variants of one MedDRA preferred term. 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.