Methionine

What is methionine?

Methionine (brand name Methio-Form) is a nutritional supplement used to make urine more acidic in cats and dogs. Urine acidifiers are used to help manage certain types of urolithiasis (urinary stones).

The U.S. Food and Drug Administration (FDA) does not review non-drug health products (e.g., herbals, nutraceuticals, shampoos, and other supplements) for safety or effectiveness before they are sold to the public. Manufacturers of non-drug health products must ensure their products are safe and labeled accurately. 

The FDA requires that these non-pharmaceuticals contain a disclaimer that says, “This product is not intended to diagnose, treat, cure or prevent any disease.” Health Canada licenses “veterinary health products” after reviewing safety, efficacy, and manufacturing information provided by the manufacturer. These products are not tested by Health Canada.

"Your veterinarian is the best source of information
about the safety of non-drug health products in pets."

Your veterinarian is the best source of information about the safety of non-drug health products in pets. Just because a product is natural does not mean it is safe. All medicines and medicinal plants are potentially toxic if used inappropriately or given at high doses. Supplements can also have side effects, like pharmaceuticals. Few supplements and herbs have been subjected to rigorous scientific trials to determine their efficacy. 

Although the information in this handout may be helpful, it also may be incomplete and may not represent the full range of effects the supplement could have on your pet.

How do I give my pet methionine?

• Methionine comes in gel, chewable, powder, and tablet forms. 
• All forms are given orally (by mouth)
• This medication may be given with or without food. 
• If your animal vomits or acts sick after receiving the drug on an empty stomach, try giving the next dose with food or a small treat. If vomiting continues, contact your veterinarian.  
• Follow your veterinarian's instructions for reconstituting powder formulations into liquid, if needed. Any liquid formulations must be measured carefully to ensure correct dosing.
• Contact your veterinarian if you have trouble measuring or giving the medication.
• Give this medication to your pet for the entire time prescribed by your veterinarian, even if it appears that your pet is feeling better.

This medication should start working within 1–2 hours, but its effects will not be outwardly noticeable.

What if I miss giving my pet the medication?

If you miss a dose, give it as soon as you remember. However, if it is almost time for the next scheduled dose, skip the missed dose and resume the regular dosing schedule. Do not give the pet two doses at once.

Are there any potential side effects from methionine?

Methionine may cause the following side effects:

• upset stomach

The following reactions are rare, but if they occur, contact your veterinarian immediately:

• an allergic reaction such as irregular breathing, rash, fever, puffiness and swelling around the face
• sudden onset of weakness, red-brown urine color, pale gums

Drug sensitivities can develop over time with repeated exposure. Your pet may have no reaction after the first few doses, but may develop a sensitivity later. It is important to watch for signs of an allergic reaction over the entire course of treatment.Other side effects may occur. If you notice anything unusual, contact your veterinarian immediately. This short-acting medication should stop working within 24 hours.

Are there any risk factors for this medication?

This medication should NOT BE USED in animals who:

• are allergic to any component of the medication
• have kidney, liver, and/or pancreatic disease
• have certain types of bladder or kidney stones
• are young (kittens)

This medication should be USED WITH CAUTION in animals who:

• have decreased liver function

Are there any drug interactions I should be aware of?

Certain medications should be USED WITH CAUTION when given with methionine, including but not limited to: 

• aminoglycosides (e.g., gentamicin)
• antiarrhythmic agents (e.g., lidocaine)
• carbonic anhydrase inhibitors (e.g., acetazolamide)
• erythromycin
• phenylpropanolamine
• potassium citrate
• salicylates (e.g., aspirin)
• zonisamide 

Be sure to tell your veterinarian about any medications (including vitamins, supplements, or herbal therapies) that your pet is taking before starting any new treatment.

Is any monitoring needed with this medication?

• Your veterinarian will perform a urine test to assess your pet’s urine pH before starting this medication and throughout treatment to ensure this medication is working.
• Your veterinarian may schedule a follow-up visit to ensure this is the right medication for the condition present. In this case, follow your veterinarian’s directions.
• At home, monitor for any abnormal changes. If these occur, discontinue the medication and contact your veterinarian.

How do I store methionine?

• Store protected from light at room temperature,
• Follow storage and expiration recommendations for specially compounded formulas.
• Keep medication out of reach of children and pets.

What should I do in case of emergency?

If you suspect an overdose or an adverse reaction to the medication, call your veterinary office immediately. If they are not available, follow their directions in contacting an emergency facility. Adverse effects should also be reported to the FDA or Health Canada.