Safety
Mighty K9 Side Effects: What to Watch For and When to Stop
The most likely side effects of Mighty K9 come from the oil: loose stool, vomiting and, over time, weight gain from 16.2 calories a serving. High-fat foods can trigger pancreatitis in some dogs (Steiner, Merck Veterinary Manual, 2025). Long-term safety of C60 in dogs is unknown, and C60 in oil turned toxic after light exposure in a mouse study (Grohn et al., 2021). Stop and call your vet if your dog seems unwell.
Written by the Mighty K9 editorial teamUpdated
The short version
Is Mighty K9 safe for dogs?
For a healthy adult dog, one 2 mL serving of olive oil is a small amount of food. The open questions are the fat for some dogs and the C60, which has never been studied long term in dogs.
Mighty K9 has three listed ingredients: extra virgin olive oil, ESS60 and a bacon flavor. The label images we have print no warning statement, so the cautions below come from veterinary sources and the research on each part.
It is sold as an animal food, not an approved drug. U.S. law has no supplement category for animals, so nobody checked its safety before sale (AAFCO, n.d. (food vs drug)).
What you might see
What are the side effects of Mighty K9?
Stomach upset is the most likely problem, because the drop is pure oil. Most cases are mild and settle once the oil is stopped or reduced, but some signs need a vet the same day.
| Sign | Likely cause | What to do |
|---|---|---|
| Loose or greasy stool | Extra fat, especially in the first week | Pause for a day, then restart with less; call the vet if it lasts |
| Vomiting once | Oil on a sensitive stomach | Stop the drops; call the vet if it happens again |
| Repeated vomiting, belly pain, weakness | Possible pancreatitis (Animal Medical Center, n.d.) | Call the vet the same day |
| Slow weight gain | 16.2 kcal a day adds up | Weigh monthly; cut treats or ask the vet |
| Itching, ear or skin flare | Possible food reaction; flavor source not listed | Stop and ask the vet |
| Refusing the bowl | Dislike of the smell or taste | Do not force it; try a carrier bite |
Weight gain
Can Mighty K9 make my dog gain weight?
Yes, if the calories are not counted. Each serving adds 16.2 kcal of pure fat, and treats and extras should stay under 10% of daily calories (Tufts Your Dog, n.d.).
About 59% of U.S. dogs were overweight or obese in a 2022 survey (APOP, 2022). Extra body weight loads the joints the product is sold to support. For a toy dog, our arithmetic shows a single serving can fill most of the treat budget.
Fat and the pancreas
Can Mighty K9 cause pancreatitis in dogs?
It could raise the risk in some dogs, because it is 100% fat. Veterinary references list high-fat foods and dietary indiscretion as risk factors for canine pancreatitis (Steiner, Merck Veterinary Manual, 2025) (Animal Medical Center, n.d.).
A daily 2 mL serving is far less fat than a plate of table scraps. Still, dogs that have had pancreatitis are kept on low-fat diets, and the Merck Veterinary Manual describes a target under 20 g of fat per 1,000 kcal for them (Steiner, Merck Veterinary Manual, 2025). Adding oil works against that.
Vomiting, belly pain, a hunched back, poor appetite, weakness and diarrhea (Animal Medical Center, n.d.). Stop the drops and call your vet the same day.
The C60 question
Is C60 safe for dogs?
Nobody knows for sure. There is no long-term safety study of C60, or of ESS60, in dogs. What exists is a handful of animal studies with mixed results.
Short rat studies
Rats given C60 in olive oil showed no chronic toxicity in a small study (Baati et al., 2012). A 14-day study at up to 3.8 mg/kg a day reported no adverse effects; its authors are linked to a C60 maker (Burres et al., 2024).
Light and mice
In a larger mouse study, C60 in olive oil left in light for 4 to 8 days killed mice given a single injected dose. Fresh oil kept from light did not (Grohn et al., 2021).
Breathed-in C60
A government study of inhaled C60 found lung effects in rats and mice (NTP, 2020). Breathing it differs from eating it, so it says little about drops.
Six beagles, nine days
Six beagles got about 150 mg of C60 a day in grape seed oil for 9 days, with no control group (Hui et al., 2023). That is nearly 100 times one serving.
The same mouse study found that commercial C60 oils varied in quality (Grohn et al., 2021). No lab report is published for Mighty K9. Read more on our ESS60 ingredient page.
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Why should Mighty K9 be kept out of light?
Because light changed C60 oil from harmless to toxic in mice. The mice that died had been injected, not fed, but the finding is a strong reason to protect the bottle (Grohn et al., 2021).
- Keep the amber bottle closed and in its box or a dark cupboard.
- Never leave it on a windowsill, a counter in the sun or a car dashboard.
- Do not pour it into a clear container or dropper.
- If a bottle sat in light for days, call +1 (302) 200-3480 before using it.
Medicines
Can I give my dog Mighty K9 with pain medicine?
Only with your vet's knowledge. No interaction study exists, and your vet should know every product your dog takes.
Never give a dog human pain relievers such as ibuprofen, naproxen, acetaminophen or aspirin without calling a vet first. FDA warns that pets process these drugs differently and that they can cause ulcers and kidney or liver failure (FDA, n.d. (pain relievers)). A stiff dog needs a vet-chosen plan, not a pill from your cabinet.
Mighty K9 is a canine supplement, not a veterinary medicine. Ask your veterinarian first if your dog has had pancreatitis, is on a low-fat or weight-loss diet, takes prescription medicine, is a puppy, or is pregnant or nursing. A 2 mL serving is all oil and carries 16.2 calories. See side effects and safety.
When to stop
When should I stop Mighty K9 and call the vet?
Stop at the first sign that your dog is unwell after starting the drops. Write down what you saw, keep the bottle, and call your veterinarian.
Stop the drops
Do not give another serving until your vet says it is fine.
Call your vet
Same day for repeated vomiting, belly pain, weakness or a dog that will not eat.
Keep the bottle
Note the lot number. The order desk at +1 (302) 200-3480 can match it to your order.
Watch the limp
A limp past a day or two needs a vet; sudden, severe lameness cannot wait (Cornell Riney Canine Health Center, n.d.).
Emergencies
What if my dog drank the whole bottle?
Call your vet or the ASPCA Animal Poison Control Center at (888) 426-4435, open 24 hours a day; a fee may apply (ASPCA, n.d.). Sixty mL of oil can cause serious stomach upset and, in some dogs, pancreatitis.
FAQ
Mighty K9 side effects FAQ
What are the side effects of Mighty K9?
The most likely are loose or greasy stools and occasional vomiting, both from the oil. Over weeks, the 16.2 calories per serving can add weight if not counted. Dogs prone to pancreatitis face a higher risk from extra fat. Long-term effects of C60 in dogs have not been studied.
Can Mighty K9 cause diarrhea?
It can. Each serving is pure oil, and a sudden increase in fat is a common reason for loose stool in dogs. Pause for a day, restart with a smaller amount, and call your vet if diarrhea lasts more than a day or comes with vomiting.
Does the FDA sign off on Mighty K9 before sale?
No. Mighty K9 is not FDA approved, and products like it are not reviewed before sale. U.S. law treats dog supplements as either animal food or drugs. An approved animal drug must show safety and effectiveness to FDA first; Mighty K9 has not gone through that.
Is C60 toxic to dogs?
There is no evidence that fresh C60 in olive oil is toxic to dogs at one serving, but there is no long-term dog study either. In mice, C60 oil left in light for several days became toxic when injected. Keeping the bottle dark matters.
How long do Mighty K9 side effects last?
Mild stomach upset from oil usually settles within a day or two of stopping. Signs that persist, worsen or include belly pain and weakness need a vet the same day. Do not wait it out if your dog will not eat or keeps vomiting.
Can a dog overdose on Mighty K9?
A dog that drinks a large amount gets a big dose of fat, which can cause vomiting, diarrhea and possibly pancreatitis. Call your vet or ASPCA Animal Poison Control at (888) 426-4435. Note how much is missing from the bottle before you call.
Is a reaction to Mighty K9 worth reporting?
Yes. Tell your vet first, then call the order desk at +1 (302) 200-3480 with your order ID and the lot number. Your vet can also report a suspected reaction to FDA's Center for Veterinary Medicine.
Who wrote this
Written and reviewed by
Plain-language pages built from the bottle label, the sales page and linked veterinary and government sources.
Last updated . Read our editorial standards and how we check reviews. This website is run by a U.S. retail partner, not by the manufacturer. This site is paid a commission when you buy through our order links.
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