Tacrolimus vs Azathioprine: side effects in FDA adverse event reports
At a glance
| Tacrolimus | Azathioprine | |
|---|---|---|
| Drug class | – | Purine Antimetabolite |
| Brand names | – | – |
| FAERS reports | 155,699 | 87,582 |
| Serious | 90% | 87% |
| Death outcome | 25,744 | 8,696 |
| Boxed warning | Yes MALIGNANCIES AND SERIOUS INFECTIONS • Increased risk for developing serious infections and malignancies with tacrolimus or other immunosuppressants that may lea | Yes - MALIGNANCY Chronic immunosuppression with azathioprine, a purine antimetabolite increases risk of malignancy in humans. Reports of malignancy include post-tra |
Signals both drugs share
| Reaction | Tacrolimus | Azathioprine | Label screen (A / B) |
|---|---|---|---|
| Lung transplant rejection | 366 · PRR 165.9 | 93 · PRR 38.8 | Labeled (related wording) / Labeled (related wording) |
Labeled signals distinctive to Tacrolimus
- Post transplant lymphoproliferative disorder — n=3,045, PRR 210.3 Labeled (related wording)
- Polyomavirus-associated nephropathy — n=1,817, PRR 501.3 Labeled adverse reaction
- Bk virus infection — n=1,551, PRR 116.6 Labeled adverse reaction
- Transplant dysfunction — n=1,248, PRR 335.9 Labeled (related wording)
- Renal transplant failure — n=600, PRR 210.5 Labeled (related wording)
- Parvovirus b19 infection — n=531, PRR 206.6 Labeled adverse reaction
- Graft loss — n=357, PRR 128.3 Labeled adverse reaction
- Human polyomavirus infection — n=295, PRR 178.5 Labeled (related wording)
Labeled signals distinctive to Azathioprine
- Hepatosplenic t-cell lymphoma — n=155, PRR 171.2 Labeled — boxed warning
- Cholestasis of pregnancy — n=100, PRR 67.0 Labeled adverse reaction
Common questions
Which has more reported side effects, Tacrolimus or Azathioprine?
Tacrolimus has 155,699 FAERS reports and Azathioprine 87,582. 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 (90% vs 87%) is a better like-for-like signal of the kind of problems reported.
Which side effects do Tacrolimus and Azathioprine share?
Both drugs carry disproportionality signals for lung transplant rejection. Shared signals often reflect a shared drug class or the condition both are used for.
Is Tacrolimus or Azathioprine 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.