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What is Oregano Poisoning?

Oregano contains an essential oil that is capable of causing gastrointestinal upset in cats. This reaction is generally mild, and only occurs if a lot of plant material has been consumed. The real danger exists from owners believing the plant to be safe for cats, and in turn thinking that oregano essential oil would also be safe, as it is used medicinally in a lot of home remedies. Oregano essential oil, or OEO, is far too concentrated to be used on cats. It is high in both phenols and terpenoids, which cats can not properly digest due to a lack of glucuronyl transferase digestive enzymes in the liver. This can result in a toxic reaction and permanent liver damage to the cat.

Oregano is a widely used culinary herb that can grow successfully in many climates. Its scientific name is “Origanum vulgare hirtum” of the Lamiaceae plant family, and it is sometimes called Greek oregano. The herb is often kept in a pot but can also be used as a ground covering for its rapid growth. Oregano grows long stems covered with rounded, green leaves. It is very aromatic, especially when the leaves are crushed. Small white flowers bloom from the plant during the late summer months. 

Symptoms of Oregano Poisoning in Cats

Plant consumption usually only results in mild digestive upset, if any illness even develops. Severe reactions can occur from administering oregano essential oil internally or topically to a cat. Symptoms may develop over time if use is continuous. All signs to watch for include:

  • Nausea
  • Vomiting
  • Diarrhea
  • Shallow breathing
  • Oral irritation
  • Anorexia
  • Liver-related issues
  • Collapse

Causes of Oregano Poisoning in Cats

The oregano plant is likely to be found around the home as it is a very common cooking herb that is easy to grow. Some people keep oregano growing in their kitchen for easy access while cooking. A cat will likely only come into contact with oregano essential oil if someone in the household is purposely applying it to the animal. Many mistakenly believe that OEO may be used in place of antibiotics, which can lead to a very dangerous situation for the affected cat. 

Diagnosis of Oregano Poisoning in Cats

If your cat begins to exhibit any of the symptoms listed above, take it in to be professionally assessed by a veterinarian. It is of the utmost importance that you disclose any at home treatments you have been giving to your cat in full detail. This can help quicken the diagnostic process immensely and get your cat the medical attention it needs. The veterinarian will likely ask what ailment was being treated with oregano essential oil so that it also may be addressed after the cat has been stabilized. You may also be asked to provide your cat's full medical history to help identify any health issues that may pose further complications.

The vet will then perform a complete physical examination of the cat including an oral or dermal examination if burns from OEO application have occurred. All vital signs and functions will be measured, including temperature, blood pressure and heart rate. A sample of the cat's blood will be taken so that standard tests can be run to measure levels of cells and minerals in the bloodstream. These tests generally include a complete blood count and a biochemical profile. Urinalysis may be used to determine how the liver is functioning. In extreme cases, a biopsy of the liver may be taken and sent for microscopic examination.

Treatment of Oregano Poisoning in Cats

In cases which a cat has eaten oregano plant material, it is likely that the only course of action will be to monitor the animal until symptoms subside. If a cat has been poisoned by oregano essential oil more severe reactions may develop.

Supportive Care 

Depending on the symptoms that have manifested in the cat, extra care and hospitalization may be required. Intravenous fluids may need to be administered to counteract dehydration from extended periods of gastrointestinal distress. The cat's breathing may need to be regulated throughout the episode. The cat will be kept as comfortable as possible during hospitalization. 

Wash Oral Cavity 

If the cat has experienced burns or irritation from OEO exposure, its mouth will need to be flushed with water. Any other body parts that have contacted the oil may also need to be thoroughly washed to soothe the inflammation.

Recovery of Oregano Poisoning in Cats

If the oregano plant has been ingested by a cat, a full and quick recovery is to be expected with no lasting health effects. Consuming oregano essential oil has the potential to cause permanent damage to the liver which may require ongoing treatment to manage. Skin and oral burns should heal as soon as OEO administration has been stopped.

Do not use oregano essential oil on cats under any circumstances. Even topical use can result in irritation and pain for the cat. Consult with your veterinarian before using any other type of essential oil on your cat to confirm that it will not cause injury to the animal. Keep all potted herbs out of your cat's reach to prevent them from being eaten. Keeping your cat indoors can protect it from contacting toxic plants in surrounding areas and gardens.

Oregano Poisoning Questions and Advice from Veterinary Professionals

2 Years
Serious condition
1 found helpful
Serious condition

Has Symptoms

Face swollen

My cat ingested oregano oil will he go into liver failure ? We went to the emergency vet they said if he did that he could die tomorrow.. not comforting. Have cats lived from having essential oil on them?

Dr. Callum Turner, DVM
Dr. Callum Turner, DVM
3320 Recommendations

Many people used essential oils on their pets without understand that they need to be diluted first. I do not have any toxicology data for oregano oil in cats, but if treatment isn’t taken immediately then liver failure is an almost certainty. Regards Dr Callum Turner DVM

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Isabella , lupey and minina
Domestic cats
14 Years
Fair condition
1 found helpful
Fair condition

Has Symptoms


So oregano oil can be used to cure toe nail fungus and i want to try it. I have 3 senior cats 2 at 14 and 1 at 17 . Is it safe to use knowing they will smell it everyday ? I put it on once and even with keeping socks on i smelt of oregano oil its very potent

Dr. Callum Turner, DVM
Dr. Callum Turner, DVM
3320 Recommendations
Normally I recommend against the use of oregano or any other oils around pets; however if you are using it make sure they are unable to lick or ingest any of the oil and monitor them for any signs of poisoning. I cannot say it is 100% safe to use or not, but use with caution and monitor for any symptoms listed on this page. Regards Dr Callum Turner DVM

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1 Year
Moderate condition
1 found helpful
Moderate condition

Has Symptoms

Ringworm..dry itchy spots.

Hi! I have a cattery severalcactcsc hace ringworm. I've had a horrible time getting rid of it & read that diluted oregano oil can get rid of it. Do you have any info on this? Any help would be appreciated. Thank you!

Dr. Michele King, DVM
Dr. Michele King, DVM
1611 Recommendations
I don't have any knowledge of Oregano oil treating Ringworm, but there are shampoos and systemic medications that the cats may need. Strict cleaning and washing of all bedding helps in a cattery situation, as does isolation of affected animals. I hope that all goes well.

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