Based on NIH | Is it true that metformin can be given to chickens, and what dosage cautions should be considered?

Metformin use in chickens is not an approved or standard practice, and any use would be off‑label under veterinary oversight only. Evidence in birds is limited to small experimental studies, not clinical dosing guidelines, so there is no established safe or effective routine dose for poultry. ^[1] Off‑label administration also carries risks such as lactic acidosis, reproductive effects, and unknown withdrawal times for food‑producing animals. ^{[2] [3]}

What the research shows

• Limited experimental work in young chickens has explored metformin’s metabolic effects. In a lab setting, a single oral dose around 300 mg/kg body weight lowered plasma glucose and mannose within about 1 hour, with kidney enzyme changes resembling mammalian patterns; however, expected liver suppression was not seen, suggesting species‑specific differences in mechanism. ^[1] These findings indicate physiological effects but do not establish clinical indications or dosing for disease treatment in poultry. ^[1]
• Separate experimental work in prepubertal cockerels given metformin for three weeks showed reduced testicular weight and about a 50% drop in testosterone, with markers suggesting impaired germ cell differentiation. ^[3] This raises potential concerns for fertility and development in growing male birds. ^[3]

Not approved for poultry

Metformin is a human antidiabetic drug with labeling focused on humans, highlighting key risks like lactic acidosis with serious morbidity and mortality when it occurs. ^[2] There are no veterinary‑approved metformin products or official poultry dosing guidelines, and no defined meat/egg withdrawal periods, which is critical for food safety compliance. ^[2]

Safety cautions if a veterinarian considers off‑label use

Because formal poultry dosing guidelines do not exist, veterinarians would need to balance uncertain benefits against risks noted in human labeling and avian studies:

• Lactic acidosis risk: Metformin can precipitate lactic acidosis, especially with renal impairment, hypoxia, dehydration, or severe illness; when lactic acidosis happens, it has a high fatality rate. ^[2] Birds with kidney compromise, shock, hypothermia, or severe infection would be particularly vulnerable. ^[2]
• Renal elimination: Metformin is excreted unchanged by the kidneys, so reduced renal function increases drug accumulation and risk; dosing must be cautious or avoided if kidney function is impaired. ^{[4] [5]}
• Reproductive effects: In young male chickens, subchronic exposure reduced testicular mass and testosterone and affected germ cell populations, suggesting potential impacts on fertility and development. ^[3] This is particularly important for breeding stock or growing birds. ^[3]
• Species‑specific pharmacology: Chicken liver responses differed from mammals in experimental work, meaning dose‑response and target effects may not translate from human or mammalian data. ^[1] This uncertainty makes extrapolating human doses unsafe. ^[1]
• Overdose concerns: Very large ingestions in humans have led to hypoglycemia in some cases and frequent lactic acidosis reports; while avian thresholds are unknown, this underscores the need for strict dosing controls and monitoring. ^[6]
• Food safety: Without established withdrawal times, drug residues could persist in meat or eggs, creating regulatory and public health risks in food‑producing birds. ^[2]

Practical guidance

• Veterinary oversight only: Any consideration of metformin in chickens should be restricted to controlled research or case‑by‑case decisions by a licensed veterinarian, with documented rationale and monitoring plans. ^[2]
• Avoid in breeders and juveniles: Given observed testicular and hormonal impacts in prepubertal males, using metformin in breeding flocks or growing birds would be particularly risky. ^[3]
• Screen for renal and systemic illness: Because the drug is renally cleared and lactic acidosis risk rises with hypoxia or dehydration, birds should be assessed and stabilized before any off‑label use is contemplated. ^{[2] [4] [5]}
• Start low, monitor closely: If a veterinarian proceeds, conservative dosing with close monitoring of activity, feed intake, hydration, droppings, and, where feasible, blood biochemistry would be prudent due to species differences and lack of reference dosing. ^[1]
• Respect food regulations: In layers or meat birds, the absence of established withdrawal periods typically argues against use because of residue compliance and consumer safety requirements. ^[2]

---

Bottom line

• It is technically possible to give metformin to chickens, but there is no approved indication, no standard dosing, and meaningful safety and regulatory concerns. ^{[1] [2]}
• Experimental doses around 300 mg/kg have been used in research to study acute metabolic effects, not as a clinical recommendation, and subchronic exposure has shown adverse reproductive effects in young males. ^{[1] [3]}
• Because of lactic acidosis risk, renal clearance issues, species‑specific responses, and lack of withdrawal times, any use should be avoided in food‑producing or breeding birds unless a veterinarian determines it is absolutely necessary and can monitor closely. ^{[2] [4] [3] [1]}