Pet Safety / Compounds / Metformin

Is Metformin safe for dogs and cats?

Moderate risk for pets

Metformin is not used therapeutically in dogs but accidental ingestion of human metformin tablets is a common ASPCA APCC call; its toxicology in dogs is distinct from humans because dogs develop hypoglycemia from metformin, unlike humans. Canine hypoglycemia: the mechanism of metformin-induced hypoglycemia in dogs is unclear — it may involve suppression of hepatic glucose output plus secondary effects; canine metabolic response differs from humans. Toxic dose (dogs): ASPCA APCC data indicate GI signs (vomiting) at >50 mg/kg; hypoglycemia possible at >100 mg/kg; the standard 500 mg tablet would be toxic at these doses to smaller dogs. Signs: vomiting, lethargy, hypoglycemia (trembling, weakness, seizures if severe); lactic acidosis at high doses similar to humans. Treatment: emesis if early; activated charcoal; blood glucose monitoring; dextrose supplementation if hypoglycemia develops; supportive care; monitoring for lactic acidosis at very high doses. Formulation considerations: extended-release 500 mg and 1000 mg tablets are common — dogs may ingest multiple XR tablets; despite slow release, toxicity from XR formulation follows a delayed time course.

What is metformin?

The IUPAC name is 3-(diaminomethylidene)-1,1-dimethylguanidine.

Also known as: 3-(diaminomethylidene)-1,1-dimethylguanidine, 1,1-Dimethylbiguanide, N,N-dimethylimidodicarbonimidic diamide, Metiguanide.

IUPAC name
3-(diaminomethylidene)-1,1-dimethylguanidine
CAS number
657-24-9
Molecular formula
C4H11N5
Molecular weight
129.16 g/mol
SMILES
CN(C)C(=N)N=C(N)N
PubChem CID
4091

Risk for dogs

Moderate risk

Metformin is not used therapeutically in dogs but accidental ingestion of human metformin tablets is a common ASPCA APCC call; its toxicology in dogs is distinct from humans because dogs develop hypoglycemia from metformin, unlike humans. Canine hypoglycemia: the mechanism of metformin-induced hypoglycemia in dogs is unclear — it may involve suppression of hepatic glucose output plus secondary effects; canine metabolic response differs from humans. Toxic dose (dogs): ASPCA APCC data indicate GI signs (vomiting) at >50 mg/kg; hypoglycemia possible at >100 mg/kg; the standard 500 mg tablet would be toxic at these doses to smaller dogs. Signs: vomiting, lethargy, hypoglycemia (trembling, weakness, seizures if severe); lactic acidosis at high doses similar to humans. Treatment: emesis if early; activated charcoal; blood glucose monitoring; dextrose supplementation if hypoglycemia develops; supportive care; monitoring for lactic acidosis at very high doses. Formulation considerations: extended-release 500 mg and 1000 mg tablets are common — dogs may ingest multiple XR tablets; despite slow release, toxicity from XR formulation follows a delayed time course.

Regulatory consensus

1 regulatory bodyhas classified Metformin.

AgencyYearClassificationNotes
FDA—Approved for type 2 diabetes mellitus in adults and children ≥10 years

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 pets encounter metformin

  • 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 Metformin:

  • Therapeutic alternatives (consult prescriber)
    Trade-offs: Drug-specific. Cannot substitute without medical guidance.
    Relative cost: 1.2-2×

Frequently asked questions

Is metformin safe for pets?

Metformin is not used therapeutically in dogs but accidental ingestion of human metformin tablets is a common ASPCA APCC call; its toxicology in dogs is distinct from humans because dogs develop hypoglycemia from metformin, unlike humans. Canine hypoglycemia: the mechanism of metformin-induced hypoglycemia in dogs is unclear — it may involve suppression of hepatic glucose output plus secondary effects; canine metabolic response differs from humans. Toxic dose (dogs): ASPCA APCC data indicate GI signs (vomiting) at >50 mg/kg; hypoglycemia possible at >100 mg/kg; the standard 500 mg tablet would be toxic at these doses to smaller dogs. Signs: vomiting, lethargy, hypoglycemia (trembling, weakness, seizures if severe); lactic acidosis at high doses similar to humans. Treatment: emesis if early; activated charcoal; blood glucose monitoring; dextrose supplementation if hypoglycemia develops; supportive care; monitoring for lactic acidosis at very high doses. Formulation considerations: extended-release 500 mg and 1000 mg tablets are common — dogs may ingest multiple XR tablets; despite slow release, toxicity from XR formulation follows a delayed time course.

What products contain metformin?

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

See Metformin in the pets app

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

Open in pets View raw API data

Sources (2)
  1. FDA Prescribing Information: Metformin (Glucophage) — biguanide T2DM; lactic acidosis; renal contraindication eGFR <30; contrast media; B12 deficiency; PCOS off-label; pediatric ≥10yr; cardiovascular outcomes benefit; GI tolerability; hemodialysis (2023) (2023) — regulatory
  2. ASPCA Animal Poison Control Center: Cardiac Drug Toxicosis in Pets — statin myopathy in cats; beta-blocker bradycardia dogs; CCB toxicity (amlodipine/diltiazem); ACE inhibitor renal effects; warfarin anticoagulant; furosemide; toxic dose thresholds (2023) (2023) — veterinary

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 →