Lenalidomide vs Cyclophosphamide: side effects in FDA adverse event reports
At a glance
| Lenalidomide | Cyclophosphamide | |
|---|---|---|
| Drug class | Thalidomide Analog | Alkylating Drug |
| Brand names | – | – |
| FAERS reports | 419,568 | 175,993 |
| Serious | 64% | 96% |
| Death outcome | 53,763 | 35,641 |
| Boxed warning | Yes EMBRYO-FETAL TOXICITY, HEMATOLOGIC TOXICITY, and VENOUS and ARTERIAL THROMBOEMBOLISM Embryo-Fetal Toxicity Do not use lenalidomide capsules during pregnancy. Le | No |
Signals both drugs share
| Reaction | Lenalidomide | Cyclophosphamide | Label screen (A / B) |
|---|---|---|---|
| B-cell type acute leukaemia | 317 · PRR 39.0 | 167 · PRR 35.9 | Likely indication confounding / Likely indication confounding |
| Follicular lymphoma | 114 · PRR 7.6 | 256 · PRR 50.9 | Likely indication confounding / Likely indication confounding |
Labeled signals distinctive to Lenalidomide
- Plasma cell myeloma — n=17,121, PRR 38.5 Labeled (related wording)
- Neuropathy peripheral — n=12,164, PRR 7.2 Labeled adverse reaction
- Multiple myeloma — n=2,370, PRR 49.7 Labeled — boxed warning
- Myelodysplastic syndrome — n=2,154, PRR 8.6 Labeled — boxed warning
- Cytopenia — n=1,476, PRR 6.9 Labeled — boxed warning
- Squamous cell carcinoma of skin — n=761, PRR 7.1 Labeled adverse reaction
- Plasma cell myeloma refractory — n=625, PRR 46.1 Labeled (related wording)
- Plasma cell leukaemia — n=313, PRR 54.3 Labeled (related wording)
Labeled signals distinctive to Cyclophosphamide
- Cytomegalovirus infection reactivation — n=1,352, PRR 55.1 Labeled (related wording)
- Cystitis haemorrhagic — n=1,125, PRR 46.1 Labeled (related wording)
- Hepatitis b reactivation — n=791, PRR 39.3 Labeled (related wording)
- Viral haemorrhagic cystitis — n=284, PRR 80.2 Labeled (related wording)
- Secondary immunodeficiency — n=283, PRR 36.8 Labeled (related wording)
- Cystitis viral — n=177, PRR 103.7 Labeled (related wording)
- Ovarian failure — n=143, PRR 42.7 Labeled adverse reaction
- Cystitis bacterial — n=100, PRR 49.4 Labeled (related wording)
Common questions
Which has more reported side effects, Lenalidomide or Cyclophosphamide?
Lenalidomide has 419,568 FAERS reports and Cyclophosphamide 175,993. More reports does not mean more dangerous: volume follows how widely and how long a drug has been used, prescription vs over-the-counter status, and publicity. The seriousness share (64% vs 96%) is a better like-for-like signal of the kind of problems reported.
Which side effects do Lenalidomide and Cyclophosphamide share?
Both drugs carry disproportionality signals for b-cell type acute leukaemia, follicular lymphoma. Shared signals often reflect a shared drug class or the condition both are used for.
Is Lenalidomide or Cyclophosphamide safer?
FAERS cannot answer that: it has no denominator and no comparator. Use this page to see which risks are already on each label and which signals are unlabeled, then check the prescribing information and your clinician for your situation.
Sources: openFDA FAERS pair statistics (OpenPV build 2026-09-14), FDA labels via openFDA, openFDA count queries for seriousness and deaths. Pair chosen because it is a commonly searched comparison. Generated 2026-10-08.