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Azathioprine Side Effects

The most commonly reported side effects of azathioprine include off label use, condition aggravated, and arthralgia, based on 88,805 FDA adverse event reports from 2004 to 2025. 14.7% of reports found the drug to be ineffective.

Azathioprine side effects

Percentages show how often each reaction appears relative to total reports for azathioprine.

1
Off Label Use15.4%13,641
2
Drug Ineffective14.7%13,058
3
Condition Aggravated7.6%6,721
4
Arthralgia6.5%5,793
5
Diarrhoea5.7%5,039
6
Fatigue5.7%5,018
7
Nausea5.5%4,882
8
Crohn^s Disease4.9%4,365
9
Headache4.8%4,241
10
Pain4.7%4,136
11
Drug Intolerance4.6%4,057
12
Rheumatoid Arthritis4.3%3,783
13
Pneumonia4.2%3,702
14
Malaise4.1%3,685
15
Intentional Product Use Issue3.9%3,468

These are voluntary reports and do not establish that azathioprine caused these reactions.

Report severity

86.9%Serious77,158 reports
34.8%Hospitalizations30,923 reports
10.1%Fatal8,953 reports

Seriousness is determined by the reporter, not by OpenClaim.

Azathioprine drug interactions

Other drugs that appear in adverse event reports alongside azathioprine. Drugs flagged as a suspected cause appear in the first column. Drugs taken at the same time but not suspected appear in the second.

Also suspected

1
Infliximab25.1%22,320
2
Adalimumab22.4%19,894
3
Prednisone13.6%12,042
4
Methotrexate13.5%12,019
5
Rituximab11.1%9,886
6
Hydroxychloroquine-sulfate8.7%7,755
7
Etanercept8.4%7,458
8
Mycophenolate8.2%7,289
9
Prednisolone7.9%7,031
10
Cyclosporine7.9%7,027
11
Tacrolimus6.8%6,035
12
Leflunomide6.7%5,916
13
Methylprednisolone6.0%5,326
14
Tocilizumab5.9%5,199
15
Vedolizumab5.8%5,181

Taken alongside

1
Prednisone18.9%16,818
2
Acetaminophen7.7%6,878
3
Mesalamine7.1%6,324
4
Ergocalciferol6.7%5,923
5
Prednisolone5.2%4,584
6
Omeprazole5.0%4,461
7
Hydroxychloroquine-sulfate5.0%4,429
8
Folic-acid4.6%4,042
9
Methylprednisolone4.4%3,871
10
Aspirin4.3%3,814
11
Pantoprazole-sodium4.2%3,771
12
Calcium4.2%3,749
13
Levothyroxine-sodium4.1%3,659
14
Methotrexate4.0%3,591
15
Diphenhydramine3.1%2,792

Co-occurrence in adverse event reports does not establish a drug interaction. Patients often take multiple medications, and these lists reflect prescribing patterns rather than causal relationships. Consult a healthcare provider about potential drug interactions.

Who reports azathioprine side effects

53.8% of azathioprine adverse event reports involve female patients and 32.5% involve male patients. The largest age group is adult at 74%. These figures reflect who reports side effects, not underlying risk.

Sex

Female53.8%
Male32.5%
Unknown13.7%

Age group

< 21.6%
2–112.7%
12–174.2%
18–6473.7%
65+17.9%

What is azathioprine used for

Conditions and purposes for which patients were taking azathioprine when the adverse event was reported.

Abdominal AbscessAbdominal DiscomfortAbdominal DistensionAbdominal PainAbdominal Pain UpperAbdominal Wall HaematomaAbscess IntestinalAbscess LimbAcanthamoeba KeratitisAccidental OverdoseAcquired Epidermolysis BullosaAcquired HaemophiliaAcute Cutaneous Lupus ErythematosusAcute Disseminated EncephalomyelitisAcute Febrile Neutrophilic Dermatosis

Showing 15 of 1,583 indications

Azathioprine brand names and reporting trend

Azathioprine is sold under brand names including Imuran, Azathioprine Sodium.

Brand names

Imuran77,649
Azathioprine Sodium3,823

Quarterly reports (20042025)

20052010201520202025

An upward trend reflects increased FAERS reporting overall, not necessarily increased risk.

Taking azathioprine with another medication?

Ask OpenClaim about your specific drug combination. Get a sourced report using FDA data, drug labels, and medical literature.