Is Propylene glycol safe for dogs and cats?
Low risk for petsPropylene glycol is FDA GRAS for use in dog food at concentrations up to approximately 5% (semi-moist food applications) and is widely used as a humectant in semi-moist dog treats and some canned formulations. At permitted food concentrations, propylene glycol is well tolerated by dogs — dogs do not exhibit the heightened erythrocyte sensitivity to PG oxidative stress that characterizes cats. Very large doses of propylene glycol (substantially above any food concentration) could theoretically cause CNS depression in dogs via the same mechanism as other glycols, but this is not a realistic scenario from food or product use. Propylene glycol is a component of some veterinary topical and systemic formulations (PG is used as a vehicle for injectable medications). The distinction in regulatory treatment between dogs (GRAS, allowed in food) and cats (banned in food) reflects the documented species difference in erythrocyte vulnerability.
What is propylene glycol?
The IUPAC name is propane-1,2-diol.
Also known as: propane-1,2-diol, 1,2-propanediol, 1,2-Propylene glycol, 1,2-dihydroxypropane.
- IUPAC name
- propane-1,2-diol
- CAS number
- 57-55-6
- Molecular formula
- C3H8O2
- Molecular weight
- 76.09 g/mol
- SMILES
- CC(CO)O
- PubChem CID
- 1030
Risk for dogs
Low riskPropylene glycol is FDA GRAS for use in dog food at concentrations up to approximately 5% (semi-moist food applications) and is widely used as a humectant in semi-moist dog treats and some canned formulations. At permitted food concentrations, propylene glycol is well tolerated by dogs — dogs do not exhibit the heightened erythrocyte sensitivity to PG oxidative stress that characterizes cats. Very large doses of propylene glycol (substantially above any food concentration) could theoretically cause CNS depression in dogs via the same mechanism as other glycols, but this is not a realistic scenario from food or product use. Propylene glycol is a component of some veterinary topical and systemic formulations (PG is used as a vehicle for injectable medications). The distinction in regulatory treatment between dogs (GRAS, allowed in food) and cats (banned in food) reflects the documented species difference in erythrocyte vulnerability.
Risk for cats
Moderate riskPropylene glycol (1,2-propanediol; PG) is an FDA-approved food additive (GRAS for humans and dogs) widely used as a humectant, preservative, and solvent in food, cosmetics, pharmaceuticals, and animal products. Cats are uniquely sensitive to propylene glycol due to their reduced erythrocyte glutathione stability compared to other species — PG produces Heinz body formation (oxidative damage to hemoglobin) and subsequent hemolytic anemia in cats. This sensitivity led the FDA to prohibit propylene glycol in cat food in 1996 (21 CFR 582.4666). Despite this regulatory action, PG exposure in cats continues through: (1) accidental ingestion of dog food containing PG (dog foods may legally contain up to 5% PG as a humectant in semi-moist formulations); (2) topical application of PG-containing pet products (ear cleaners, skin treatments, some flea products); (3) human food products shared with cats (semi-moist treats, certain gel-based products). Signs of PG toxicosis in cats include Heinz body anemia, decreased red blood cell survival, methemoglobinemia, and lethargy. The severity is dose-dependent; the FDA ban on PG in cat food was triggered by documentation of subclinical Heinz body formation in cats fed PG-containing foods. Products labeled for use in dogs should not be offered to or applied to cats if they contain propylene glycol.
Regulatory consensus
3 regulatory and scientific bodies have classified Propylene glycol. The classifications differ — that's the data.
| Agency | Year | Classification | Notes |
|---|---|---|---|
| EPA CTX / Genetox | — | Genotoxicity: positive (Ames: positive, 9 positive / 4 negative reports) | |
| EPA CTX / Genetox | — | Genotoxicity: positive (Ames: positive, 9 positive / 4 negative reports) | |
| EPA CTX / Skin-Eye | — | skin irritation: in vivo: Studies Indicate No Significant Irritation (score: low) |
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 propylene glycol
- Industrial Facilities — Manufacturing plants, Chemical storage areas, Waste treatment sites
- Occupational Environments — Factories, Warehouses, Transportation vehicles
-
Fragrance
— perfume, cologne, scented personal care products, household fragrance products, candles
Identified in Fragrance Ingredient Safety Priority Research database (2,325 ingredients)
Safer alternatives
Lower-risk approaches that achieve a similar outcome to Propylene glycol:
-
Physical/mechanical pest control (IPM)
Trade-offs: More labor-intensive. May not be sufficient for severe infestations.Relative cost: 1.2-2×
Frequently asked questions
Is propylene glycol safe for pets?
Propylene glycol is FDA GRAS for use in dog food at concentrations up to approximately 5% (semi-moist food applications) and is widely used as a humectant in semi-moist dog treats and some canned formulations. At permitted food concentrations, propylene glycol is well tolerated by dogs — dogs do not exhibit the heightened erythrocyte sensitivity to PG oxidative stress that characterizes cats. Very large doses of propylene glycol (substantially above any food concentration) could theoretically cause CNS depression in dogs via the same mechanism as other glycols, but this is not a realistic scenario from food or product use. Propylene glycol is a component of some veterinary topical and systemic formulations (PG is used as a vehicle for injectable medications). The distinction in regulatory treatment between dogs (GRAS, allowed in food) and cats (banned in food) reflects the documented species difference in erythrocyte vulnerability.
What products contain propylene glycol?
Propylene glycol appears in: Manufacturing plants (Industrial facilities); Chemical storage areas (Industrial facilities); Factories (Occupational environments); Warehouses (Occupational environments); perfume (Fragrance).
Why do regulators disagree about propylene glycol?
Propylene glycol has been classified by 3 agencies including EPA CTX / Genetox, EPA CTX / Genetox, EPA CTX / Skin-Eye, 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 Propylene glycol in the pets app
Look up products containing propylene glycol, compare to alternatives, and explore the full data record.
Open in pets View raw API dataSources (2)
- US FDA: Propylene Glycol in Animal Food — Final Rule Prohibiting Use in Cat Food (21 CFR 582.4666) and GRAS Status for Dog Food (1996) — regulatory
- ASPCA Animal Poison Control Center: Propylene Glycol — Heinz Body Anemia Risk in Cats and Species Differences in Erythrocyte Sensitivity (2022) — 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 →