PetMD Editorial
By PetMD Editorial
Published: July 18, 2014

Drug Info

  • Common Name: Ammonil, Methio-Form
  • Generics: Yes
  • Drug Type: Urinary Acidifier
  • Used For: To prevent and treat types of kidney and bladder stones
  • Species: Dogs, Cats
  • Administered: Oral
  • How Dispensed: Prescription Only
  • Available Forms: Tablets
  • FDA Approved: Yes


Methionine is used to prevent and treat types of kidney and bladder stones.

Dosage and Administration

Methionine should be given according to your veterinarian’s instructions. 

Methionine dosage should be adjusted to maintain a urine pH of below 6.6.

Give Methionine with food to reduce gastrointestinal upset.

Missed Dose?

If a dose of Methionine is missed, give the dose as soon as possible. If it is almost time for the next dose, skip the missed dose and continue your regular schedule. Do not give two doses at one time.

Possible Side Effects

Side effects from Methionine could include but not limited to:

Please contact your veterinarian immediately if you notice any side effects.


Do not use in animals that are allergic to Methionine, animals with liver, pancreatic or kidney disease, or those with urate kidney or bladder stones.

Methionine should not be given to animals that are on a urine acidifying diet (i.e. s/d, c/d) unless directed your veterinarian as it may lead to signs associated with overdose.

Methionine is not recommended for use in kittens or animals under the age of 1, or pregnant or lactating animals.


Methionine should be stored at room temperature. Store out of children’s reach.

Drug Interactions

When using Methionine, please consult your veterinarian with any other medications you are currently giving your pet, including supplements, as interaction could occur.  Methionine has shown to have interactions with gentamicin, amikacin, quinidine and erythromycin. Drugs other than what is listed may also interact with Methionine.

Signs of Toxicity/Overdose

Overdose of Methionine may cause:

  • Anorexia
  • Loss of coordination
  • Cyanosis (blue or purple coloration of the skin or mucous membranes)

Overdosing may result in metabolic acidosis which is life-threatening. If you suspect or know you pet has had an overdose, please contact your veterinarian, an emergency vet clinic, or the Pet Poison Helpline at (855) 213-6680 immediately.

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