Cbd oil for cats side effects

6 Potential Side Effects of CBD Oils for Cats: What You Should Know!

Cat owners are turning to holistic approaches and natural supplements like CBD oils to treat their felines more than Western medicine. And, as these alternative treatments keep proving their effectiveness, it isn’t much of a surprise that more and more pet owners are getting invested in the oils.

Although substantial research studies on these natural oils are still ongoing, the findings and the health benefits of CBD oils on humans look incredibly promising.

But then, there haven’t been official significant scientific findings on the oil’s impacts on pets even though research on humans has proven effective. So, is CBD oil safe for cats?

What is CBD Oil?

The cannabis plant contains over a hundred active compounds that humans have been using to treat various ailments for a long time. Cannabidiol, or simply CBD, is one of the main compounds extracted from the plant to be used for medicinal purposes.

After extraction, feline owners blend the CBD compound in oils like coconut, olive, avocado, hempseed, and palm oil. These oils act as carriers, just like essential oils, where owners give them to cats orally.

The primary purpose for the extraction of this compound from the cannabis plant is to create a high concentration of CBD, a substance with medicinal and therapeutic properties. Unlike the major active compound in cannabis – tetrahydrocannabinol (THC), CBD does not have a euphoric or psychoactive effect that may leave its users “high.”

Since CBD is not mind-altering, cat enthusiasts have been using it to improve the quality of life and contain feline issues like:

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How Do CBD Oils Work in Cats?

Animals such as cats and dogs have an endocannabinoid system that helps keep their bodies healthy. This system works as the body’s control system to facilitate healing.

Since it is innate, kitties produce endocannabinoid substances known as endogenous cannabinoids. After release, these substances travel the bloodstream and help the cat’s body system maintain an internal balance known as homeostasis. This balance dictates to the body how it should respond to external events.

Therefore, when the CBD enters the body, it interacts with the endocannabinoid system to prevent the endocannabinoids from breaking down, pushing it to react accordingly. For this reason, people use CBD oils as a gentle supplement for their felines.

However, as much as some cat parents attest to major success in managing feline’s various health concerns using these oils, you should understand that cats and humans don’t process supplements the same way. For this reason, it would be best to contact your veterinarian before initiating it to your kitty.

Potential Side Effects of CBD Oils for Cats

Although no research has confirmed the substance’s safety and effectiveness in cats, some doctors claim that CBD oils are generally safe for cats. However, cat owners need to stay alert and consider potential side effects after administering CBD oil to their cats.

It would be best to visit the vet or ensure that you adhere to the correct dosage to combat some of these effects. Check out some of the adverse effects of CBD oils on your kitty.

1. Drowsiness

Although cat parents use CBD oils to treat stress and anxiety in cats, the calming effect afterward can turn to drowsiness, especially if in high doses.

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2. Diarrhea

Gastrointestinal upset is the worst and grossest adverse reaction of CBD oils for cats, especially if it manifests as diarrhea. However, cat owners can find it hard to know whether the bowel issue’s real cause is the oil or the feline’s eating habits.

The best way to discern is to remove the questionable foods one by one, including the CBD oil, to see if the situation eases.

3. Vomiting

Another most common side effect of initiating the CBD oil to your kitty is vomiting. The reason is, CBD oil is bitter, a taste that may prompt your pet to reject and vomit it.

Although some CBD products are flavored and may taste better, it can take you a lot of effort and time to find the most ideal for your kitty. It is vital to make out if the vomiting is due to the oil and take appropriate actions like consulting with your vet since excessive vomiting can dehydrate your pet and worsen it.

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4. May Interact and Inhibit other Pet Meds

CBD substance is an inhibitor of enzymes like cytochrome P450 that metabolize drugs in the liver. The interaction has the potential effect of affecting the metabolism of any drug that your pet might be using. For this reason, cat owners need to check with their vets for recommendations and advice on which drugs to use and the ones to stop when initiating CBD oils.

5. Lowers Blood Pressure

You can expose your kitty to a drop in blood pressure if you administer the CBD oils in high doses. Your cat may start experiencing a brief feeling of light-headedness, and it may feel sluggish and sleepy.

It would be best to check with your vet immediately and mention that you were treating it using CBD oil.

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6. Dry Mouth

While you may hate your kitty’s saliva, saliva in a cat’s mouth signals good health. It helps maintain a feline’s dental hygiene and digestion. However, according to scientific research, CBD oils can decrease saliva production in cats, causing their mouth to dry.

Mouth dryness can affect a kitty’s teeth, gums, cause bad breath and difficulty in swallowing. For this reason, your kitty gets thirsty faster and drinks more water than usual to make up for the lack of fluids in the mouth.

If you notice this effect in your pet, it would be best to reduce the CBD dose and seek help from a physician it does not get better.


Cat parents share an incredible bond with their pets and will always find ways to ensure their cat’s health and well-being. And while the efficacy of this holistic treatment is still inconclusive, there’s no doubt that this versatile oil might be the key to your feline’s well-being and happiness.

Although it may be tempting to share a dog’s or human’s CBD oil with your cat, only give your cat something tailor-made for it. The reason is, ingredients that may benefit humans may be harmful to your feline friend.

As always, cat owners should check with their vets first before introducing these supplements to their pets.

CBD for Pets: Only Mild Side-effects Even with the Highest Doses

In journalism and media industry for more than twenty years, worked for a number of media companies. Business editing, research and PR specialist. Covering industry and science news for Ilesol Pharmaceuticals.

CBD for Pets: Only Mild Side-effects Even with the Highest Doses

CBD is safe for pets. The newest research shows excellent tolerability of CBD oil formulations in cats and dogs, with carrier oil probably responsible for gastrointestinal adverse effects.

Online surveys show that there is a growing interest in the potential therapeutic uses of cannabinoids in pets. In the most developed markets, such are the U.S. and Canada, when pet owners purchase cannabis products, they mostly purchase them for the management of pain, inflammation, and anxiety in their animal companions.

The existing data suggest that there are differences in the metabolism of cannabinoids across different species. For example, rodents, dogs, monkeys, and humans have different CBD and THC metabolic profiles. The differences in the behavioral and physiological effects of cannabinoids across species have also been reported.

‘Start low and go slow’

Following these notions, a study published in Frontiers in Veterinary Science in February 2020 looked into determining the safety and tolerability of escalating doses of three cannabis oil formulations, containing predominantly CBD, THC, or CBD and THC. A hallmark dosing strategy for cannabis initiation is said to be “start low and go slow”, to avoid adverse effects associated with THC. Slow upward dose titration was used in this study, meaning the dose was increased very gradually. A secondary objective was to determine blood levels of CBD, THC, and their metabolites at higher dose levels of CBD (>50 mg/kg) and THC (>30 mg/kg).

The dose levels in this study went up to 640.5 mg of CBD. Previously, there was evidence that even lower doses than 20 mg per kg cause side effects, with gastrointestinal upset as the most common clinical sign.

In this randomized, placebo-controlled, and blinded study, 20 healthy adult purpose-bred Beagle dogs, aged three to 7.8 years, weighing 10 to 14 kilos, were randomized to one of five treatment groups with four dogs per group (two males, two females). The subjects of the trial were placed into steel boxes with a sufficient water supply and fed once a day with standard commercial feed.

The study observes that the dogs tolerated dose escalation of the CBD oil well. CBD for pets seems to be completely safe. Even with this high dosage, they were experiencing only mild adverse effects. The conclusion of this study is that the CBD-predominant oil formulations are safer and more tolerated in dogs than oil formulations containing higher concentrations of THC.

Also, CBD oil had the least effect on the food intake and physical activity of the dogs. Food intake decreased on dosing days as compared to non-dosing days by 4.6%. Nonetheless, their body weight remained stable throughout the study, as with other dogs included.

Risk of ataxia with THC

While CBD for pets proved to be safe, there should be some concern with THC. The most striking side-effect happened to one of four dogs in the THC oil group. The subject experienced severe ataxia at the 7th dose and was discontinued from further dosing. Two of four dogs in the CBD/THC oil group experienced severe ataxia and/or lethargy at the fourth or fifth doses (one dog at the fourth dose and a second dog at the fifth dose) and thus further dosing ceased for all dogs in this group. Again, with CBD oil or placebo group, no dogs were discontinued as a result of adverse effects.

Side-effects in high dosage

All in all, the adverse effects were reported in all 20 dogs across the five groups. Of the total number of adverse effects observed across the entire study (n = 505), 104 of them occurred in the placebo groups, and 401 occurred across the three cannabinoid groups: 80 with CBD oil (10 doses), 206 with THC oil (10 doses), and 115 with CBD/THC oil (five doses).

Compared to dogs receiving CBD oil, dogs receiving THC oil experienced more than double side effects. Those effects were 7-fold more neurological and constitutional, 5-fold more dermatological, and 3-fold more ocular and respiratory. The greatest difference between the CBD oil and THC oil groups seems to be the first dose given. Altogether, there was a 7-fold difference in the average number of adverse effects experienced per dog.

When intaking the remaining nine doses, dogs receiving the THC oil experienced between a 2- and 3-fold greater number of adverse effects per dose vs. dogs receiving the CBD oil. While CBD for pets can be used without concerns of serious side-effects when it comes to the CBD/THC oil group, there was a steep increase in the average number of adverse effects per dog at the fifth dose; each of the three dogs experienced 10 adverse effects at this dose vs. the other two cannabinoid oil groups wherein an average of 4.8 adverse effects (THC oil group) and 1.5 adverse effects (CBD oil group) were experienced per dog. The scientists find it noteworthy that the total number of adverse effects and the adverse effect profile in the CBD oil group were comparable to the MCT placebo oil group. Moreover, across the cannabinoid oil groups, at each escalating dose, dogs in the CBD oil group experienced a lower average number of adverse effects as compared to the THC oil group and the CBD/THC oil group.

Mild adverse effects accounted for 479 of the 505 in the total study (94.9%). The mild adverse effects occurred in all dogs and mainly manifested as gastrointestinal (nausea, emesis, diarrhea), constitutional (lethargy, hyperesthesia), or neurological (muscle tremor, ataxia) symptoms.

No moderate adverse effects with CBD oil

There were no severe adverse effects in the CBD oil group at any of the doses tested. Severe adverse effects accounted for 4 of the 505 total study (0.8%) and occurred in three of 20 dogs (15%) across two groups: THC oil (one dog at the seventh dose) and CBD/THC oil (one dog at the fourth dose and a second dog at the fifth dose). They manifested as severe ataxia and/or lethargy and were transient, resolving in 9–28 h.

CBD can potentiate the effects of THC

In blood, there was at least a 2-fold increase in total bilirubin or plasma levels of liver enzymes. The enzyme mostly affected by the highest doses of CBD was alkaline phosphatase (ALP). After the final dose, the levels exceeded the upper limit of normal. The altered liver functions were observed only in CBD and CBD/THC groups, while plasma levels of liver enzymes and total bilirubin were stable in the THC oil group. All abnormalities resolved seven days following the final dose.

Considering that the CBD/THC group was the only group with recorded severe side effects, the scientist concluded that CBD is not always a functional antagonist of THC. In fact, CBD can potentiate, rather than antagonize, the psychoactive and physiological effects of THC. The interaction depends on the dosage and the sequence of administration – whether CBD is administered before THC (pharmacokinetic interaction more likely) or concurrently with THC. In very high doses, CBD for pets could be most safely used as an isolate.

CBD for pets: The first feline safety study

There are no published studies on the efficacy of cannabinoids in cats but a brand new study on the safety and tolerability of escalating cannabinoid doses in healthy cats, published in the Journal of Feline Medicine and Surgery in March 2021, shows that cats can tolerate maximum doses of 30.5 mg/kg CBD (CBD oil), 41.5 mg/kg THC (THC oil) or 13.0:8.4 mg/kg CBD:THC (CBD/THC oil).

Although CBD for pets is gaining in popularity, this was the first feline study to explore the safety and tolerability of CBD and THC, alone and in combination, in a controlled research setting. In a placebo-controlled, blinded study, 20 healthy adult cats were randomized to one of five treatment groups and given up to 11 escalating doses.

All observed adverse events were mild, transient, and resolved without medical intervention. Gastrointestinal adverse effects were more common with formulations containing medium-chain triglyceride oil (MCT). Again, the constitutional (lethargy, hypothermia), neurologic (ataxia), and ocular (protrusion membrana nictitans) adverse effects were more common with oils containing THC (CBD/THC and THC oils).

Previously, a 2019 study showed that 2 mg per kg twice daily was well tolerated in both, cats and dogs. In this study, the doses went up to 30.5 mg per kg of CBD and 41.5 mg per kg of THC. For the combination of CBD and THC, the maximum dose used was 13.0/8.4 mg/kg. The subjects were fasted, kept in steel boxes with sufficient water supply, and exercised together daily for at least one hour, except on dosing days or when an adverse event was being monitored.

All adverse effects were mild

This study investigated 11 escalating volumes/doses of placebo or test formulations with at least three days separating doses. The total study duration was 71 days.

The study included 20 randomized subjects, aged 1.0–1.2 years, weighing over four kilograms. Interestingly, body weight increase over the treatment phase was significant for the CBD group compared with the MCT oil placebo. The CBD/THC oil group showed a small but significant decrease in body weight relative to the sunflower (SF) oil placebo group, as well as the THC oil group and the CBD oil group, whereas the CBD group exhibited a small increase in body weight relative to the THC oil group. Following the completion of the last dose, the CBD/THC oil group exhibited a gain in weight relative to the SF placebo oil group.

Most importantly, all the adverse effects in the study were rated as mild. Adverse effects that occurred within 24 h of dose administration across 11 escalating doses were classified as gastrointestinal (27.6%), respiratory (15.4%), neurologic (14.6%) or ocular (8.3%), or as constitutional signs (29.9%; non-specific clinical signs that can affect multiple body systems and have several potential causes). Cardiovascular adverse effects (pale mucous membranes, bradycardia, tachycardia) and respiratory adverse effects (primarily tachypnoea), occurred with uniform frequency across all treatment groups.

Intolerability to MCT carrier oil?

The occurrence of gastrointestinal adverse effects significantly differed between the two placebo groups – their occurrence was greater with MCT oil (n = 43) than SF oil (n = 1). Moreover, 99% of emesis and diarrhea occurrences (n = 89/90) were with MCT oil formulations (placebo, CBD oil, THC oil). The occurrence of the two most frequently observed gastrointestinal adverse effects – hypersalivation and emesis – did not significantly differ between CBD or THC vs MCT oil. Emesis was not observed in the CBD/THC or SF oil treatment groups but was more frequently observed with CBD than THC oil. Hypersalivation did not significantly differ between CBD, THC, or CBD/THC treatment groups.

Neurologic adverse effects in cats occurred more frequently with THC oil and CBD/THC oil than with CBD oil but did not differ between THC and CBD/THC groups. Again, ataxia occurred predominantly following the administration of THC-containing oils, with eight-fold and 11-fold greater frequency than with CBD oil, but did not differ between THC and CBD/THC treatment groups. In the CBD oil group, ataxia did not occur until the ninth (24.9 mg/kg CBD + 0.94 mg/kg THC) or tenth dose (27.7 mg/kg CBD + 1 mg/kg THC).

Liver markers remained within the normal reference intervals at all measured time points. The exception was one cat that received the MCT placebo and had elevated alanine aminotransferase (ALT) that resolved in one week. Furthermore, the comparison of gastrointestinal adverse effects between the two placebo oils suggests that SF oil is better tolerated by healthy cats than MCT oil. Therefore, emesis and diarrhea secondary to CBD or THC oil administration may be explained by intolerability to the MCT carrier oil rather than the cannabinoids themselves.

These findings support continuing research on the potential therapeutic uses of orally delivered CBD in cats, and for its consideration as a safe treatment option in veterinary medicine. CBD for pets will most probably continue to grow in popularity.

Reviewed by Sasha Bajilo, founder of ILESOL Pharmaceuticals, an industrial scale producer of CBD products and formulations. Expert on Hemp/Cannabis policy, member of the Croatian Ministry of Health regulatory commission for medical cannabis.

FAQs about CBD Use in Pets

A: Cannabidiol, or CBD, is a cannabinoid produced by the plant Cannabis sativa, commonly known as marijuana. After many anecdotal reports of CBD’s potential health benefits, studies are now underway to look at the potential benefits of CBD for controlling pain from conditions such as osteoarthritis, calming anxious pets, and as a possible treatment for epilepsy in dogs. CBD is being used by many pet owners today, so it’s essential to know enough about it to discuss the potential risks of use.

Q: Is CBD psychoactive?

A: No; however, there are several possible reasons a dog who has ingested CBD may look high:

  1. The product that the pet ingested contains both THC and CBD. There are many products on the market, some even labeled for use in pets, that contain both CBD and THC at varying concentrations, so check the labels or look up the product online to see what’s in it.
  2. The pet ingested enough of a CBD product to cause THC toxicity. Hemp can legally contain up to 0.3% THC, so if a pet ingests a large amount of a hemp-based CBD product, mild THC toxicity can occur.
  3. The product has not undergone quality assurance testing and contains THC.
  4. The dog also found some marijuana or THC edibles. Ask about any other cannabis products in the home.

Q: What are the most common signs reported in pets after the ingestion of CBD products?

A: Vomiting, lethargy, inappetence, and diarrhea are the most common clinical signs reported. Ataxia can occasionally occur with large ingestions.

Q: How do I treat these cases?

A: Most cases need no treatment, aside from symptomatic care for gastrointestinal upset if it occurs. If it’s a large dose, where the THC content might be a factor, mild sedation, urinary incontinence, hyperesthesia, and ataxia could develop, and the pet should be confined to prevent injury from misadventure. If you see significant signs that look like THC toxicity, treat the pet in front of you and provide IV fluid support, anti-nausea medication, and good nursing care as needed.

Q: Is there anything special I need to know about pet hemp treat overdoses?

A: Products sold as “soft chews” can have an osmotic effect when large amounts of chews are ingested and pull fluid from the body into the gastrointestinal tract. In mild cases, this can lead to diarrhea and dehydration. In severe cases, hypernatremia, hyperglycemia, hyperkalemia, azotemia, and acidosis can occur. Aggressive fluid therapy, while monitoring hydration status and electrolytes in these pets, is critical.

Q: What about interactions with other medications? Any long-term effects to be concerned about?

A: CBD is an inhibitor of cytochrome P450 and has the potential to affect the metabolism of other drugs. While this appears to be of minimal clinical significance in most cases, this may be important when CBD is used in a pet for seizure control. Doses of other anticonvulsants may need to be adjusted. Remember that owners may discontinue anticonvulsants on their own if they feel that CBD is controlling their pet’s seizures, so this is an important discussion to have.

CBD has also been shown to cause dose-dependent elevations in liver enzymes in various safety studies. This has not been noted in acute overdose situations but could be a concern in pets taking CBD long-term. Monitoring liver enzymes and total bilirubin in these pets is recommended.