Baby Safety / Compounds / Azathioprine

Is Azathioprine safe for babies and kids?

Context-dependent for kids

(Babies-specific data is limited; this page draws from human pregnant context.) Pregnancy alters the metabolism and distribution of Azathioprine, potentially increasing fetal exposure. The developing embryo/fetus is vulnerable during organogenesis (weeks 3-8) and neurological development. Placental transfer should be assumed.

What is azathioprine?

The IUPAC name is 6-(3-methyl-5-nitroimidazol-4-yl)sulfanyl-7H-purine.

Also known as: 6-(3-methyl-5-nitroimidazol-4-yl)sulfanyl-7H-purine, Azothioprine, Azanin, Azathioprin.

IUPAC name
6-(3-methyl-5-nitroimidazol-4-yl)sulfanyl-7H-purine
CAS number
446-86-6
Molecular formula
C9H7N7O2S
Molecular weight
277.27 g/mol
SMILES
CN1C=NC(=C1SC2=NC=NC3=C2NC=N3)[N+](=O)[O-]
PubChem CID
2265

Risk for babies

Context-dependent

Pregnancy alters the metabolism and distribution of Azathioprine, potentially increasing fetal exposure. The developing embryo/fetus is vulnerable during organogenesis (weeks 3-8) and neurological development. Placental transfer should be assumed.

No specific reproductive toxicity data identified, but pregnancy-specific safety data is limited for most chemicals. Precautionary minimization of exposure is recommended.

What to do: Minimize exposure during pregnancy and lactation. Consult healthcare provider regarding specific risks. Consider alternative products with lower hazard profiles.

Risk for pregnant and nursing people

Context-dependent

Pregnancy alters the metabolism and distribution of Azathioprine, potentially increasing fetal exposure. The developing embryo/fetus is vulnerable during organogenesis (weeks 3-8) and neurological development. Placental transfer should be assumed.

No specific reproductive toxicity data identified, but pregnancy-specific safety data is limited for most chemicals. Precautionary minimization of exposure is recommended.

What to do: Minimize exposure during pregnancy and lactation. Consult healthcare provider regarding specific risks. Consider alternative products with lower hazard profiles.

Regulatory consensus

10 regulatory and scientific bodies have classified Azathioprine. The classifications differ — that's the data.

AgencyYearClassificationNotes
IARC2012Group 1
US EPA2000probable human carcinogen (Group B2)
EPA CTX / NTP RoC—Known Human Carcinogen
EPA CTX / IARC—Group 1 - Carcinogenic to humans
EPA CTX / CalEPA—Known human carcinogen
EPA CTX / Genetox—Genotoxicity: positive (Ames: positive, 15 positive / 1 negative reports)
EPA CTX / Genetox—Genotoxicity: positive (Ames: positive, 15 positive / 1 negative reports)
EPA CTX / Skin-Eye—Skin Sensitization: Category 1 (score: high)
EPA CTX / Skin-Eye—Eye Irritation: Category 6.4A (Category 2A) (score: high)
EPA CTX / Skin-Eye—Skin Irritation: Category 6.3A (Category 2) (score: high)

Regulators apply different standards of evidence — animal-data weighting, exposure-pattern assumptions, epidemiological power thresholds — which is why two scientific bodies can review the same data and reach different conclusions. The disagreement is the data.

Where kids encounter azathioprine

  • Industrial Facilities — Manufacturing plants, Chemical storage areas, Waste treatment sites
  • Occupational Environments — Factories, Warehouses, Transportation vehicles

Safer alternatives

Lower-risk approaches that achieve a similar outcome to Azathioprine:

  • Safer process chemistry; Green chemistry alternatives; Exposure controls
    Trade-offs: Requires R&D investment to redesign synthesis routes; may reduce yield or throughput initially; long-term benefits include reduced waste treatment costs, regulatory compliance, and worker safety; 12 Principles of Green Chemistry framework available.
    Relative cost: 2-5×

Frequently asked questions

What products contain azathioprine?

Azathioprine appears in: Manufacturing plants (Industrial facilities); Chemical storage areas (Industrial facilities); Factories (Occupational environments); Warehouses (Occupational environments).

Why do regulators disagree about azathioprine?

Azathioprine has been classified by 10 agencies including IARC, US EPA, EPA CTX / NTP RoC, EPA CTX / IARC, EPA CTX / CalEPA, with differing conclusions. Regulators apply different standards of evidence (animal data weighting, exposure-pattern assumptions, epidemiological power thresholds), which is why two scientific bodies can review the same data and reach different conclusions. See the regulatory consensus table on this page for the full picture.

See Azathioprine in the baby app

Look up products containing azathioprine, compare to alternatives, and explore the full data record.

Open in baby View raw API data

Sources (2)
  1. IARC Monographs Volume 100A: Pharmaceuticals — Azathioprine Group 1; NHL/PTLD in Transplant Recipients; EBV-Driven PTLD; NMSC 60–100× Elevation; 6-Thioguanine UV-A Photosensitization; HHV-8 Kaposi Sarcoma (2012) — iarc_monograph
  2. US EPA Azathioprine: Group B2 Probable Carcinogen; NIOSH Hazardous Drug Closed System Handling; Transplant Recipient Cancer Registry Data; Healthcare Worker Occupational Exposure; Pharmaceutical Wastewater Contamination (2000) — regulatory

Reference data, not professional advice. Aggregates publicly available regulatory and scientific data; not a substitute for veterinary, medical, legal, or regulatory advice. Why we built ALETHEIA →