Drug · FAERS side-effect profile with label screen
Thioguanine side effects: what 2,099 FDA adverse event reports show
Drug class
Not stated in label
Brand names
Tabloid
openFDA label
Who reports
2,099 reports · 95% serious · 376 with death outcome · 39% female
openFDA FAERS counts, all years, deduplication not applied
Used for
a) Acute Nonlymphocytic Leukemias TABLOID brand Thioguanine is indicated for remission induction and remission consolidation treatment of acute nonlymphocytic leukemias. However, it is not recommended for use during maintenance therapy or similar long-term continuous treatments due to the high risk of liver toxicity (see WARNINGS and ADVERSE REACTIONS).
FDA label, Indications and Usage
What it is
DESCRIPTION TABLOID brand Thioguanine was synthesized and developed by Hitchings, Elion, and associates at the Wellcome Research Laboratories. It is one of a large series of purine analogues which interfere with nucleic acid biosynthesis and has been found active against selected human neoplastic diseases.
FDA label, Description section
Boxed warning
None in the current label
How to read this page. FAERS is a spontaneous-reporting system: counts are not incidence rates and a signal is not proof of causation.
Each reaction below is run through an automated screen — is the term in the FDA label (known), in the indications (the disease being treated), an administrative/coding term, or none of these (unlabeled)?
That screen is mechanical text matching, not a causality assessment. The 30 hand-written Bradford Hill assessments are on the causality assessment page. Not medical advice.
Causality screen of the 40 strongest signals
Labeled adverse reaction 5Labeled (related wording) 3Likely indication confounding 4Reporting / coding artifact 1Lab value / disease marker 2Not in label — unassessed 25
What the badges mean
- Labeled adverse reaction The exact term appears in the label's warnings or adverse-reactions sections: a known, expected effect. The FAERS signal confirms the label rather than discovering anything.
- Labeled (related wording) The label describes this effect under different wording (e.g. 'neutropenia' for 'neutrophil count decreased'). Treated as known.
- Likely indication confounding The term appears in the label's indications: reports probably describe the disease being treated (or its progression), not a drug effect. Classic confounding by indication.
- Reporting / coding artifact An administrative, monitoring or exposure term (product issue, off-label use, 'test normal', overdose...). Not a biological reaction; a high PRR here reflects how reports are coded.
- Lab value / disease marker A laboratory result, investigation or disease-activity marker (antibody positive, CRP abnormal, swollen joint count) not described in the label. These usually mirror the monitored disease or testing protocol rather than a drug effect; not screened further.
- Not in label — unassessed Not found in the label text, not an artifact pattern. This is a genuine candidate for a formal causality assessment (Bradford Hill / WHO-UMC); it has NOT had one here.
Strongest disproportionality signals
Flagged terms (PRR ≥ 2, χ² ≥ 4, n ≥ 10), ranked by PRR; infinite PRRs (no comparator reports) excluded. The EBGM column is a second, shrinkage-based estimate (MGPS) with its 5th percentile EB05 and the BCPNN IC025; a pair flagged by PRR alone is marked PRR-only and should be read as fragile. The strata column recomputes the PRR on serious reports only and flags pairs whose reports are unusually skewed by sex or come mostly from consumers rather than clinicians. 35 further terms are in the interactive explorer. Reaction links open the term's cross-drug page.
Show:
| Reaction | Reports | PRR 95% CI · ROR · χ²/p | EBGM EB05 · IC025 | Label screen | Serious-only & strata | Trial cross-check |
|---|---|---|---|---|---|---|
| Haematotoxicity | 138 | 150.9 128.3–177.6ROR 161.5 · χ² 20,107 / p <1e-300 | 145.7 EB05 126.4 · IC025 +6.3 3/3 methods agree | Not in label — unassessed | serious PRR 92.6 | no trial data cached |
| Febrile neutropenia | 486 | 73.9 68.3–79.9ROR 95.8 · χ² 34,706 / p <1e-300 | 73.1 EB05 67.8 · IC025 +5.9 3/3 methods agree | Labeled (related wording) related wording | serious PRR 44.4 · 91% clinician | no trial data cached |
| Mucosal inflammation | 60 | 23.0 18.0–29.6ROR 23.7 · χ² 1,242 / p 2e-272 | 22.9 EB05 18.4 · IC025 +3.9 3/3 methods agree | Labeled (related wording) related wording | serious PRR 14.3 | no trial data cached |
| Hepatotoxicity (liver damage) | 49 | 22.1 16.8–29.2ROR 22.6 · χ² 966 / p 2e-212 | 21.9 EB05 17.2 · IC025 +3.7 3/3 methods agree | Not in label — unassessed | serious PRR 13.4 · 95% clinician | no trial data cached |
| Acute myeloid leukaemia | 34 | 21.9 15.7–30.5ROR 22.2 · χ² 655 / p 9e-145 | 21.6 EB05 16.1 · IC025 +3.5 3/3 methods agree | Likely indication confounding shares a disease stem with the indications wording | serious PRR 13.3 · ♀ 62% (drug 39%) · 100% clinician | no trial data cached |
| Hepatomegaly | 21 | 21.3 13.9–32.6ROR 21.5 · χ² 385 / p 4e-86 | 20.8 EB05 14.3 · IC025 +3.1 3/3 methods agree | Labeled adverse reaction exact term | serious PRR 14.0 | no trial data cached |
| Hepatic encephalopathy | 17 | 18.2 11.3–29.3ROR 18.4 · χ² 259 / p 1e-58 | 17.6 EB05 11.3 · IC025 +2.8 3/3 methods agree | Not in label — unassessed | serious PRR 11.1 | no trial data cached |
| Hyperbilirubinaemia | 18 | 17.5 11.0–27.7ROR 17.6 · χ² 263 / p 2e-59 | 16.9 EB05 11.0 · IC025 +2.8 3/3 methods agree | Not in label — unassessed | serious PRR 9.6 | no trial data cached |
| Bacteraemia | 20 | 17.0 11.0–26.3ROR 17.2 · χ² 285 / p 3e-64 | 16.5 EB05 11.0 · IC025 +2.9 3/3 methods agree | Not in label — unassessed | serious PRR 10.4 | no trial data cached |
| Sputum discoloured | 16 | 16.9 10.4–27.6ROR 17.1 · χ² 224 / p 6e-51 | 16.3 EB05 10.1 · IC025 +2.7 3/3 methods agree | Not in label — unassessed | serious PRR 13.4 | no trial data cached |
| Neurotoxicity | 28 | 16.1 11.2–23.3ROR 16.3 · χ² 382 / p 2e-85 | 15.8 EB05 11.3 · IC025 +3.0 3/3 methods agree | Not in label — unassessed | serious PRR 9.9 · 100% clinician | no trial data cached |
| Myelodysplastic syndrome | 23 | 15.9 10.6–23.9ROR 16.1 · χ² 306 / p 8e-69 | 15.5 EB05 10.6 · IC025 +2.9 3/3 methods agree | Not in label — unassessed | serious PRR 9.3 · ♀ 68% (drug 39%) · 100% clinician | no trial data cached |
| Pancytopenia (all blood cells low) | 86 | 15.4 12.6–19.0ROR 16.1 · χ² 1,148 / p 6e-252 | 15.3 EB05 12.8 · IC025 +3.5 3/3 methods agree | Labeled adverse reaction exact term | serious PRR 9.1 · 94% clinician | no trial data cached |
| Osteonecrosis (bone death) | 51 | 15.4 11.7–20.2ROR 15.8 · χ² 672 / p 2e-148 | 15.2 EB05 12.0 · IC025 +3.3 3/3 methods agree | Not in label — unassessed | serious PRR 9.4 · 92% clinician | no trial data cached |
| Hemiparesis | 26 | 15.3 10.4–22.4ROR 15.4 · χ² 332 / p 2e-74 | 14.9 EB05 10.4 · IC025 +2.9 3/3 methods agree | Not in label — unassessed | serious PRR 10.0 | no trial data cached |
| Ascites | 42 | 14.3 10.6–19.3ROR 14.6 · χ² 506 / p 3e-112 | 14.0 EB05 10.7 · IC025 +3.1 3/3 methods agree | Labeled adverse reaction exact term | serious PRR 8.8 | no trial data cached |
| Decreased activity | 15 | 14.0 8.5–23.2ROR 14.1 · χ² 168 / p 9e-39 | 13.0 EB05 7.7 · IC025 +2.4 3/3 methods agree | Likely indication confounding term in indications | serious PRR 12.8 | no trial data cached |
| Leukaemia | 11 | 11.7 6.5–21.0ROR 11.7 · χ² 97 / p 4e-23 | 9.8 EB05 5.2 · IC025 +2.0 3/3 methods agree | Likely indication confounding term in indications; also in warnings | serious PRR 7.1 | no trial data cached |
| Coagulopathy | 19 | 11.4 7.3–17.9ROR 11.5 · χ² 171 / p 3e-39 | 10.4 EB05 6.6 · IC025 +2.4 3/3 methods agree | Not in label — unassessed | serious PRR 6.8 | no trial data cached |
| Full blood count abnormal | 12 | 11.4 6.5–20.0ROR 11.4 · χ² 103 / p 1e-24 | 9.7 EB05 5.3 · IC025 +2.0 3/3 methods agree | Lab value / disease marker | serious PRR 9.2 | no trial data cached |
| Blood bilirubin increased | 30 | 11.1 7.8–15.8ROR 11.2 · χ² 265 / p 7e-60 | 10.5 EB05 7.4 · IC025 +2.6 3/3 methods agree | Lab value / disease marker | serious PRR 7.7 | no trial data cached |
| Candida infection (yeast infection) | 18 | 10.8 6.8–17.1ROR 10.9 · χ² 150 / p 8e-35 | 9.7 EB05 6.1 · IC025 +2.3 3/3 methods agree | Not in label — unassessed | serious PRR 9.4 | no trial data cached |
| Oral candidiasis (oral thrush) | 14 | 10.8 6.4–18.1ROR 10.8 · χ² 114 / p 6e-27 | 9.3 EB05 5.4 · IC025 +2.1 3/3 methods agree | Not in label — unassessed | serious PRR 9.1 | no trial data cached |
| Seasonal allergy | 15 | 10.6 6.4–17.6ROR 10.7 · χ² 121 / p 2e-28 | 9.2 EB05 5.5 · IC025 +2.1 3/3 methods agree | Not in label — unassessed | serious n=15 | no trial data cached |
| Device related infection | 16 | 10.4 6.4–16.9ROR 10.4 · χ² 126 / p 1e-29 | 9.1 EB05 5.6 · IC025 +2.2 3/3 methods agree | Reporting / coding artifact | serious PRR 6.0 | no trial data cached |
| Bacterial infection | 19 | 10.2 6.5–16.0ROR 10.3 · χ² 149 / p 1e-34 | 9.1 EB05 5.9 · IC025 +2.3 3/3 methods agree | Not in label — unassessed | serious PRR 7.2 | no trial data cached |
| Neutropenia (low neutrophils (infection-fighting cells)) | 134 | 9.9 8.4–11.7ROR 10.5 · χ² 1,068 / p 2e-234 | 9.7 EB05 8.4 · IC025 +3.0 3/3 methods agree | Labeled adverse reaction exact term | serious PRR 6.1 · 91% clinician | no trial data cached |
| Bone marrow failure | 20 | 9.8 6.3–15.1ROR 9.9 · χ² 149 / p 2e-34 | 8.7 EB05 5.7 · IC025 +2.3 3/3 methods agree | Not in label — unassessed | serious PRR 5.9 | no trial data cached |
| Acute hepatic failure | 13 | 9.6 5.6–16.4ROR 9.6 · χ² 91 / p 6e-22 | 8.0 EB05 4.7 · IC025 +1.9 3/3 methods agree | Not in label — unassessed | serious PRR 5.8 | no trial data cached |
| Hepatic steatosis | 17 | 9.1 5.7–14.7ROR 9.2 · χ² 115 / p 4e-27 | 7.9 EB05 5.0 · IC025 +2.1 3/3 methods agree | Not in label — unassessed | serious PRR 6.3 | no trial data cached |
| Thrombocytopenia (low platelets) | 100 | 9.0 7.4–10.9ROR 9.4 · χ² 703 / p 3e-155 | 8.8 EB05 7.4 · IC025 +2.8 3/3 methods agree | Labeled adverse reaction exact term | serious PRR 5.6 | no trial data cached |
| Sepsis (blood infection) | 98 | 8.8 7.2–10.7ROR 9.2 · χ² 671 / p 3e-148 | 8.6 EB05 7.2 · IC025 +2.7 3/3 methods agree | Not in label — unassessed | serious PRR 5.2 · 92% clinician | no trial data cached |
| Sleep disorder due to a general medical condition | 14 | 8.7 5.1–14.6ROR 8.7 · χ² 87 / p 5e-21 | 7.2 EB05 4.4 · IC025 +1.9 3/3 methods agree | Not in label — unassessed | serious PRR 10.4 | no trial data cached |
| Neutrophil count decreased | 34 | 8.4 6.0–11.7ROR 8.5 · χ² 214 / p 8e-49 | 7.8 EB05 5.7 · IC025 +2.3 3/3 methods agree | Labeled (related wording) related wording | serious PRR 5.7 · 100% clinician | no trial data cached |
| Eosinophilia | 14 | 8.0 4.8–13.5ROR 8.1 · χ² 79 / p 3e-19 | 6.7 EB05 4.1 · IC025 +1.8 3/3 methods agree | Not in label — unassessed | serious PRR 5.1 | no trial data cached |
| Respiratory distress | 22 | 8.0 5.3–12.1ROR 8.0 · χ² 127 / p 9e-30 | 7.1 EB05 4.8 · IC025 +2.1 3/3 methods agree | Not in label — unassessed | serious PRR 4.9 | no trial data cached |
| Drug toxicity | 11 | 8.0 4.4–14.4ROR 8.0 · χ² 60 / p 4e-15 | 6.3 EB05 3.7 · IC025 +1.6 3/3 methods agree | Likely indication confounding term in indications; also in warnings | serious PRR 5.0 | no trial data cached |
| Colitis | 29 | 7.7 5.4–11.0ROR 7.8 · χ² 162 / p 2e-37 | 7.0 EB05 5.1 · IC025 +2.2 3/3 methods agree | Not in label — unassessed | serious PRR 4.8 | no trial data cached |
| Dysarthria (slurred speech) | 25 | 6.6 4.5–9.8ROR 6.7 · χ² 114 / p 5e-27 | 6.0 EB05 4.2 · IC025 +1.9 3/3 methods agree | Not in label — unassessed | serious PRR 4.8 · ♀ 12% (drug 39%) | no trial data cached |
| Septic shock | 28 | 6.5 4.5–9.4ROR 6.5 · χ² 124 / p 3e-29 | 5.9 EB05 4.3 · IC025 +1.9 3/3 methods agree | Not in label — unassessed | serious PRR 3.8 · 100% clinician | no trial data cached |
Trial evidence (ClinicalTrials.gov)
Trial cross-check not yet run for this drug (ClinicalTrials.gov pull covers the 800 most-reported drugs first).
Most frequently reported reactions
By raw co-report count, regardless of disproportionality. Common terms here are often the illness itself or generic outcomes.
| Reaction | Reports | PRR 95% CI · ROR · χ²/p | EBGM EB05 · IC025 | Label screen | Serious-only & strata | Trial cross-check |
|---|---|---|---|---|---|---|
| Febrile neutropenia | 486 | 73.9 68.3–79.9ROR 95.8 · χ² 34,706 / p <1e-300 | 73.1 EB05 67.8 · IC025 +5.9 3/3 methods agree | Labeled (related wording) related wording | serious PRR 44.4 · 91% clinician | no trial data cached |
| Haematotoxicity | 138 | 150.9 128.3–177.6ROR 161.5 · χ² 20,107 / p <1e-300 | 145.7 EB05 126.4 · IC025 +6.3 3/3 methods agree | Not in label — unassessed | serious PRR 92.6 | no trial data cached |
| Neutropenia (low neutrophils (infection-fighting cells)) | 134 | 9.9 8.4–11.7ROR 10.5 · χ² 1,068 / p 2e-234 | 9.7 EB05 8.4 · IC025 +3.0 3/3 methods agree | Labeled adverse reaction exact term | serious PRR 6.1 · 91% clinician | no trial data cached |
| Thrombocytopenia (low platelets) | 100 | 9.0 7.4–10.9ROR 9.4 · χ² 703 / p 3e-155 | 8.8 EB05 7.4 · IC025 +2.8 3/3 methods agree | Labeled adverse reaction exact term | serious PRR 5.6 | no trial data cached |
| Sepsis (blood infection) | 98 | 8.8 7.2–10.7ROR 9.2 · χ² 671 / p 3e-148 | 8.6 EB05 7.2 · IC025 +2.7 3/3 methods agree | Not in label — unassessed | serious PRR 5.2 · 92% clinician | no trial data cached |
| Pancytopenia (all blood cells low) | 86 | 15.4 12.6–19.0ROR 16.1 · χ² 1,148 / p 6e-252 | 15.3 EB05 12.8 · IC025 +3.5 3/3 methods agree | Labeled adverse reaction exact term | serious PRR 9.1 · 94% clinician | no trial data cached |
| Platelet count decreased | 67 | 6.3 5.0–8.0ROR 6.5 · χ² 294 / p 3e-66 | 6.0 EB05 4.9 · IC025 +2.2 3/3 methods agree | Labeled (related wording) related wording | serious PRR 4.0 | no trial data cached |
| Mucosal inflammation | 60 | 23.0 18.0–29.6ROR 23.7 · χ² 1,242 / p 2e-272 | 22.9 EB05 18.4 · IC025 +3.9 3/3 methods agree | Labeled (related wording) related wording | serious PRR 14.3 | no trial data cached |
| Osteonecrosis (bone death) | 51 | 15.4 11.7–20.2ROR 15.8 · χ² 672 / p 2e-148 | 15.2 EB05 12.0 · IC025 +3.3 3/3 methods agree | Not in label — unassessed | serious PRR 9.4 · 92% clinician | no trial data cached |
| Hepatotoxicity (liver damage) | 49 | 22.1 16.8–29.2ROR 22.6 · χ² 966 / p 2e-212 | 21.9 EB05 17.2 · IC025 +3.7 3/3 methods agree | Not in label — unassessed | serious PRR 13.4 · 95% clinician | no trial data cached |
| Toxicity to various agents | 46 | 2.7 2.1–3.6ROR 2.8 · χ² 49 / p 1e-12 | 2.7 EB05 2.1 · IC025 +0.9 3/3 methods agree | Likely indication confounding shares a disease stem with the indications wording | serious PRR 1.7 · 100% clinician | no trial data cached |
| Ascites | 42 | 14.3 10.6–19.3ROR 14.6 · χ² 506 / p 3e-112 | 14.0 EB05 10.7 · IC025 +3.1 3/3 methods agree | Labeled adverse reaction exact term | serious PRR 8.8 | no trial data cached |
| Alanine aminotransferase increased | 36 | 5.9 4.2–8.1ROR 5.9 · χ² 141 / p 1e-32 | 5.5 EB05 4.1 · IC025 +1.9 3/3 methods agree | Labeled (related wording) related wording | serious PRR 4.0 | no trial data cached |
| Stomatitis (mouth sores) | 34 | 5.6 4.0–7.8ROR 5.7 · χ² 124 / p 4e-29 | 5.2 EB05 3.9 · IC025 +1.8 3/3 methods agree | Labeled adverse reaction exact term | serious PRR 5.1 · ♀ 11% (drug 39%) · 100% clinician | no trial data cached |
| Neutrophil count decreased | 34 | 8.4 6.0–11.7ROR 8.5 · χ² 214 / p 8e-49 | 7.8 EB05 5.7 · IC025 +2.3 3/3 methods agree | Labeled (related wording) related wording | serious PRR 5.7 · 100% clinician | no trial data cached |
Unlabeled candidate signals
These flagged terms were not found in the FDA label text and do not match an artifact pattern. They are the pairs that would merit a structured assessment (temporality, dose-response, biological plausibility, consistency across databases, trial or cohort evidence). The screen has not done that; string-matching misses label wording, and a strong PRR can still be stimulated reporting, co-medication, or the disease itself.
- Haematotoxicity — n=138, PRR 150.9
- Hepatotoxicity — n=49, PRR 22.1
- Bacteraemia — n=20, PRR 17.0
- Neurotoxicity — n=28, PRR 16.1
- Myelodysplastic syndrome — n=23, PRR 15.9
- Osteonecrosis — n=51, PRR 15.4
- Hemiparesis — n=26, PRR 15.3
- Bone marrow failure — n=20, PRR 9.8
- Sepsis — n=98, PRR 8.8
- Respiratory distress — n=22, PRR 8.0
Want to assess one of these properly? The runbook describes the Bradford Hill / trial-evidence workflow used on the assessment page, and handoff_top1000_signals.csv lists the strongest unassessed pairs across all drugs.
Common questions
What are the most reported side effects of Thioguanine?
In FDA FAERS, the most frequently co-reported reaction terms for Thioguanine are febrile neutropenia, haematotoxicity, neutropenia, thrombocytopenia, sepsis, pancytopenia. These are report counts, not rates: FAERS has no denominator, reporting is voluntary and uneven, and a term can be reported because of the illness being treated rather than the drug.
Does Thioguanine have an FDA boxed warning?
No. The FDA label retrieved for Thioguanine has no boxed warning; see the label's Warnings and Precautions for the recognised risks.
Do FAERS signals prove that Thioguanine causes these side effects?
No. A disproportionality signal (PRR, ROR) means a reaction is reported more often with this drug than with others in the database. That can reflect a real effect, but also the disease being treated, stimulated reporting after news or litigation, co-medications, or how reports are coded. Causality needs temporality, dose-response, biological plausibility, consistency across data sources and, ideally, trial or cohort evidence. This page screens each term against the FDA label and ClinicalTrials.gov results; it does not establish causation.
Sources & methods
- FDA label via openFDA (set ID 44b0c461-47fb-4106-ba11-6ed85530235c, effective 20250108; matched on
openfda.generic_name.exact:"THIOGUANINE") - Bayesian shrinkage measures computed offline over all 1,317,300 cached pairs: BCPNN information component (IC, with Norén closed-form IC025) and MGPS empirical-Bayes geometric mean (EBGM, EB05) with a two-component gamma prior fitted by maximum marginal likelihood (α₁=0.57, β₁=0.02, α₂=1.42, β₂=0.70, w=0.17); unstratified
- FAERS pair statistics from the OpenPV build of 2026-09-14 (openFDA
count=aggregation, fieldpatient.drug.openfda.generic_name.exact, 75 reaction terms, min 3 co-reports); PRR/ROR with 95% CI, chi-square with Yates correction - Serious-only and stratified counts (serious:1, patient.patientsex, primarysource.qualification) from openFDA count queries; serious-only PRR uses the drug serious report total and the term global serious total (N_serious=11,882,979); strata shown only when n ≥ 20
- Seriousness and sex counts from openFDA
count=serious,patient.patientsex,seriousnessdeath
Page generated 2026-10-08. Label and PubChem text are retrieved automatically and may lag the current label; always check the current prescribing information. OpenPV is a beta research tool of the Open Source Medicine Foundation.