What is methylsulfonylmethane?
Methylsulfonylmethane (MSM) is a naturally occurring supplement used primarily as an anti-inflammatory and antioxidant for conditions such as arthritis and some cancers. MSM is used most often in dogs and horses, although cats may benefit as well.
MSM is often found in combination with other products such as glucosamine and chondroitin, although it can also be found as the sole ingredient in certain supplement products.
The U.S. Food and Drug Administration (FDA) does not review non-drug health supplements (e.g., herbals, nutraceuticals, shampoos, and other supplements) for safety or effectiveness before they are sold to the public. Manufacturers of non-drug health supplements must ensure their supplements are safe and labeled accurately. The FDA requires that these non-pharmaceuticals contain a disclaimer that says, “This supplement is not intended to diagnose, treat, cure or prevent any disease.” Health Canada licenses “veterinary health supplements” after reviewing safety, efficacy, and manufacturing information provided by the manufacturer. These supplements are not tested by Health Canada.
Your veterinarian is the best source of information about the safety of non-drug health supplements in pets. Just because a supplement 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 MSM?
- MSM is given orally (by mouth) and comes in the form of a powder, capsule, soft gel, tablet, or liquid.
- Give oral doses with food or after a meal to prevent stomach upset.
- Follow your veterinarian’s directions and use supplements according to their label.
- Ideally, give this supplement at the same time daily.
- Ensure access to fresh, clean drinking water.
- Wash your hands after handling. Do not handle if you have a known sensitivity to this supplement.
- If you have difficulty getting your animal to take the supplement, ask your veterinarian or pharmacist for tips to reduce the stress of medication time for both you and your pet.
This supplement should start to take effect within 1–2 weeks and improvements in clinical signs should follow several weeks later. It often takes up to 8 weeks before the supplement’s benefits may be seen.
What if I miss giving my pet the supplement?
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 or give extra doses.
Are there any potential side effects?
MSM may cause the following side effects:
- Stomach upset
- Diarrhea
- Decreased appetite
- Tiredness
- Restlessness
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 supplement should stop working within 1 to 3 days, although effects can be longer in pets with liver or kidney disease.
Are there any risk factors for this supplement?
DO NOT USE MSM in:
- Pets that are allergic to it
- Pets that are pregnant or nursing
Are there any drug interactions I should be aware of?
Several medications should be used with caution when given with MSM, including:
- Anticoagulants
- Nonsteroidal anti-inflammatory drugs (NSAIDs)
Be sure to tell your veterinarian about any medications (including vitamins, supplements or herbal therapies) that your pet is taking before starting any treatment.
Is any monitoring needed with this supplement?
- At home, monitor for abnormal changes. If any occur, discontinue the supplement and contact your veterinarian.
- Your veterinarian will let you know when and how they want to reassess your pet to ensure the supplement is working and not causing side effects.
How do I store MSM?
- Store oral supplements in a cool, dry area in tightly sealed containers to prevent accidental ingestion.
- Keep at room temperature and protect from light.
- Keep out of reach of children and pets.
- There are many formulations and manufacturers of MSM, so always follow the specific storage instructions on the product label.
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.
- Be prepared to provide information about the product and your pet’s weight and symptoms.
- Report any adverse effects to the FDA or Health Canada.
