SeriousCaution
Probiotics
Live probiotics rarely cause bacteremia or fungemia in severely immunosuppressed patients.
Recommendation: Avoid unsupervised probiotics during intense immunosuppression, neutropenia, central lines, or severe illness.
Azathioprine
Prescription ·Strong evidence ·Reviewed May 2026
Azathioprine is a thiopurine immunosuppressant used for kidney transplant rejection prophylaxis and autoimmune diseases such as rheumatoid arthritis, inflammatory bowel disease, and others when clinically appropriate. It can cause life-threatening myelosuppression, infection, hepatotoxicity, pancreatitis, and malignancy risk, with TPMT and NUDT15 genetics and xanthine oxidase inhibitor interactions strongly affecting safety.
What it's good for
- Prevention of kidney transplant rejection as part of immunosuppressive regimens3
- Steroid-sparing maintenance therapy in selected autoimmune diseases
- Treatment of rheumatoid arthritis when other therapies are unsuitable
- Maintenance therapy in selected inflammatory bowel disease patients
The bottom line
Evidence rating strong. Most-documented uses: prevention of kidney transplant rejection as part of immunosuppressive regimens, steroid-sparing maintenance therapy in selected autoimmune diseases, treatment of rheumatoid arthritis when other therapies are unsuitable. 3 sources indexed (2011–2026), with 4 interaction records on file.
The science
How it works, mechanistically.
Core mechanism
Azathioprine is converted to 6-mercaptopurine and then to active thioguanine nucleotides that interfere with de novo purine synthesis and lymphocyte proliferation. Because activated T and B lymphocytes depend heavily on purine synthesis, immune responses are suppressed. TPMT and NUDT15 activity influence active metabolite accumulation and myelotoxicity risk.2,3
Class
Purine analog immunosuppressant
Absorption
Water-soluble; take with food
Dosing
Dosing & protocol.
Common range
Transplant: often 3 to 5 mg/kg daily initially, then maintenance commonly 1 to 3 mg/kg daily. Autoimmune indications commonly start around 1 mg/kg daily and titrate cautiously by response, blood counts, liver tests, and TPMT/NUDT15 risk.
Recommended form
Oral tablet; injectable formulation in supervised settings when oral therapy is not possible
May be taken with food to reduce nausea. Consistent administration and close blood count monitoring are more important than meal timing.1
Safety
Full safety detail.
Side effects
- Leukopenia
- Thrombocytopenia
- Anemia
- Serious infections
- Nausea and vomiting
- Hepatotoxicity
- Pancreatitis
- Hypersensitivity fever or rash
- Lymphoma and other malignancies
- Nonmelanoma skin cancer risk
Contraindications
- Known hypersensitivity to azathioprine or mercaptopurine2,3
- Avoid use for rheumatoid arthritis in pregnancy unless benefits clearly outweigh risks
- Use extreme caution or dose reduction with low or absent TPMT or NUDT15 activity1
- Major interaction with allopurinol or febuxostat requires avoidance or substantial dose reduction3
- Live vaccines are generally avoided during significant immunosuppression3
Interactions
Interaction records.
ModerateConflict
Ashwagandha
Ashwagandha may have immune-stimulating effects and could conflict with immunosuppressive treatment goals in autoimmune disease or transplant.
Recommendation: Avoid without clinician approval when azathioprine is used to prevent rejection or control autoimmune activity.
ModerateCaution
Curcumin Phytosome
Curcumin may have antiplatelet effects and could add to bleeding risk if azathioprine causes thrombocytopenia.
Recommendation: Use cautiously and monitor bruising, bleeding, and platelet counts when blood counts are low.
ModerateCaution
Ginkgo Biloba
Ginkgo may increase bleeding tendency and could compound bleeding risk if azathioprine causes thrombocytopenia.
Recommendation: Avoid or monitor closely if platelet counts are low or bleeding occurs.
Sources
Sources, by evidence tier.
Numbered references. Citations throughout the page link here.
Reviews & position papers
2- 1Clinical Pharmacogenetics Implementation Consortium guideline for thiopurine dosing based on TPMT and NUDT15 genotypesNeeds reviewNo linkRelling MV et al. · Clinical Pharmacology and Therapeutics · 2019
Guideline supports dose reduction or alternative therapy in patients with reduced TPMT or NUDT15 function.
- 2Use of azathioprine in clinical medicineNeeds reviewNo linkMaltzman JS et al. · Clinical Pharmacology and Therapeutics · 2011
Review covers mechanism, clinical uses, metabolism, and adverse-effect monitoring.
Reference material
1- 3Imuran Azathioprine Tablets US Prescribing InformationNeeds reviewURLU.S. National Library of Medicine · DailyMed · 2026
Labeling describes malignancy boxed warning, transplant and RA dosing, myelosuppression, infection, hepatotoxicity, and xanthine oxidase inhibitor interactions.
Keep exploring
Deep dives & adjacent profiles.
This page is educational. Do not start, stop, or change a supplement or medication based on it without checking with a qualified healthcare professional.
Use this with your stack
Azathioprine in NutriStack.
Add it to your stack, see how it interacts with everything else you take, and get a Stack Score that updates the moment it does.