A single lick of DMSO is unlikely to poison your dog, but it’s not harmless either. DMSO (dimethyl sulfoxide) absorbs through mucous membranes almost instantly, meaning whatever your dog licked is already entering their bloodstream. The real concern depends on how much they ingested, how concentrated the product was, and whether the DMSO was mixed with other substances.
Why Licking DMSO Is Different From Skin Contact
DMSO penetrates skin within about five minutes of contact. But the tongue and mouth lining are far more absorbent. DMSO is highly permeable through mucous membranes and absorbs into tongue tissue on contact, with essentially no delay. That means your dog isn’t just tasting the DMSO. It’s entering the body rapidly through the soft tissue inside the mouth.
This fast absorption also means inducing vomiting won’t help much and is not recommended after DMSO ingestion. The compound moves into the bloodstream too quickly for vomiting to retrieve it. UC Davis School of Veterinary Medicine’s safety protocol explicitly states: do not induce vomiting if DMSO is swallowed.
The Carrier Effect: What Else Was in It?
This is often the bigger worry. DMSO is a powerful solvent that carries other substances deep into tissue and across membranes. It’s used medically for exactly this reason: it can transport drugs through layers of skin that would otherwise block them. If the DMSO product your dog licked contained other active ingredients, like anti-inflammatory drugs, pain relievers, or steroids, your dog may have absorbed those too, potentially at higher doses than expected.
Check the label of whatever product was involved. Pure DMSO on its own has relatively low acute toxicity. A DMSO gel or cream formulated with other medications is a different situation entirely, because the DMSO enhances absorption of whatever it’s mixed with. If the product contained any added drugs, call your vet or the ASPCA Animal Poison Control Center (888-426-4435) and have the product label ready.
Short-Term Symptoms to Watch For
After a small, one-time exposure to pure DMSO, most dogs show minimal symptoms. Research on dogs given DMSO orally found only minor changes in body weight, slight shifts in blood values, and increased urination (DMSO acts as a mild diuretic). Your dog may also develop a garlic or oyster-like odor on their breath. This is a well-known side effect of DMSO as the body metabolizes it, and it’s not dangerous, just unpleasant.
Watch for drooling, nausea, vomiting, diarrhea, or unusual lethargy in the hours after exposure. These would suggest your dog ingested enough to cause gastrointestinal irritation. Most dogs that lick a small amount off an owner’s skin or from a dropped applicator will not show any of these signs.
The Real Risk: Eye Damage From Repeated Exposure
Where DMSO gets genuinely dangerous for dogs is with repeated ingestion over time. Of the four species studied in toxicology research (dogs, pigs, rats, and rabbits), dogs were the most severely affected, and the damage targeted a specific organ: the eye.
Dogs given DMSO daily at high doses developed changes in the lens of the eye starting after 5 to 10 weeks. The progression followed a pattern: first, the center of the lens changed in a way that caused nearsightedness. Then, cloudy spots appeared around the edges of the lens. Eventually, the center of the lens became visibly opaque, and the gel-like fluid behind the lens was also affected. At lower doses, the same changes occurred but took longer to appear, with some effects not showing up for 9 to 10 months of daily exposure.
Even at the lowest dose tested (roughly equivalent to a teaspoon per kilogram of body weight daily), dogs developed progressive lens changes after more than six months of dosing. When dosing stopped, some of the refractive changes partially reversed, but the cloudiness in the lens did not go away at moderate and high doses. The biochemical cause appears to be a breakdown of proteins and protective compounds within the lens itself.
This means a single lick is not going to damage your dog’s eyes. But if your dog has been repeatedly getting into your DMSO supply, or if you’ve been applying it to your own joints and your dog routinely licks the area afterward, that cumulative exposure is a real concern.
What to Do Right Now
If your dog just licked a small amount of pure DMSO off your skin or from a surface, the situation is likely manageable at home. Rinse your dog’s mouth gently with water if they’ll tolerate it. Monitor them for the next few hours for any vomiting, excessive drooling, or unusual behavior. The garlic-like breath odor may linger for a day or so.
Call your vet if any of the following apply:
- The DMSO product contained other active ingredients. The carrier effect means your dog may have absorbed medications that are toxic to them at even small doses.
- Your dog ingested a large quantity. If they chewed open a bottle or drank from an open container, the volume matters significantly.
- Your dog is showing symptoms. Persistent vomiting, disorientation, or difficulty walking warrant immediate veterinary attention.
- This has happened more than once. Repeated exposure, even in small amounts, puts your dog at risk for the cumulative eye damage described above.
Preventing Future Exposure
If you use DMSO regularly for pain relief or joint issues, the most common scenario is a dog licking the application site on your skin. DMSO takes about five minutes to absorb through human skin, so covering the area or keeping your dog away from you for at least 10 to 15 minutes after application gives it time to fully absorb. Store DMSO products in closed cabinets rather than countertops. Dogs are attracted to the slight taste and unusual texture, and many will lick it repeatedly if given the chance, creating exactly the kind of chronic exposure pattern that causes lens damage.