Essiac Tea: More Snake Oil for Pets with Cancer

I recently had a patient I was treating for lymphoma, a white blood cell cancer, whose owner was interested in giving the dog Essiac Tea, a well-known herbal remedy sometimes recommended for cancer patients. In order to advise this client, I investigated this remedy, and I want to share the results of that investigation.

What Is It?

Essiac tea contains four plants:

Burdock root

Sheep Sorrel

Slippery Elm

Indian Rhubarb root

There is also a related product, Flor Essence, that contains an additional four ingredients:


Blessed thistle

Red clover


The inventor of this concoction claimed it to be a Native American recipe, however there is no evidence this is actually true, and some reason to doubt this story. In any case, the product came into use in the 1920s, and since it has been recommended as a cancer therapy and treatment for many other health problems. It is marketed as a dietary supplement, which means there is no requirement for scientific evidence showing it is safe or effective so long as those selling it don’t make any specific claims that it can prevent or treat disease. This does not stop many people, however, from making numerous claims about health benefits for a wide range of conditions, including the potential to treat or even cure cancer. These claims are made for pets as well as humans.

Does It Work?

The short answer is, “No.” The longer answer is that there is no reason to believe it has any benefits at all based on the limited research that currently exists. It is never possible to completely disprove any possible effects of any chemical compound, even eith extensive clinical testing. However, with no sound biologic rationale and no compelling evidence so far despite miraculous claims made over nearly a century, the chances of any real benefits being yet undiscovered is vanishingly low. Here are the conclusions of a number of existing:

1. Katja Boehm, CAM-Cancer Consortium. Essiac.

“There is no evidence from clinical trials to indicate that it is effective. No clinical trial has been carried out to assess its efficacy and the only published uncontrolled clinical investigation did not suggest that Essiac has an effect on tumour burden.

2. Cancer Research UK- Essiac

“There is no scientific evidence to show that Essiac can treat, prevent or cure cancer or any other serious illness in humans.”

3. National Cancer Institute- Essiac

“There is no evidence reported in peer-reviewed scientific journals to show that the exact formulas of Essiac and Flor Essence are effective in patients with cancer or other health conditions…”

4. Ulbricht C, Weissner W, Hashmi S, Rae Abrams T, Dacey C, Giese N, Hammerness P, Hackman DA, Kim J, Nealon A, Voloshin R. Essiac: systematic review by the natural standard research collaboration. J Soc Integr Oncol. 2009 Spring;7(2):73-80.

“A review of the literature on Essiac and essiac formulations showed a lack of high-quality clinical trials to substantiate any of Essiac’s traditional uses. Weak evidence from preclinical, animal, and laboratory data warranted a discussion regarding Essiac’s use for cancer, but the results are inconclusive. Several other essiac preparations are noted in the literature, adding confusion to the exact formula and its proposed benefits. In general, there is a lack of both safety and efficacy data for Essiac and essiac formulations.”

There are no research studies at all to establish efficacy in dogs and cats.

Is It Safe?
The short answer is, “Who knows?” The limited evidence in lab animals has turned up some potential risks, including actually increasing the risk of cancer. However, the quality of evidence concerning safety is no better than that concerning any benefits. All of the individual ingredients have been reported to have undesirable side effects in humans, though the seriousness of these or the effects of using the individual ingredients together has not been studied. It is important to remember that anything which has any effect at all on the body can potentially have undesirable effects. The lack of good evidence does not mean the product is safe, only that we don’t know whether it is safe or not.

Bottom Line
There is no reason to believe Essiac has any benefits for dogs or cats with cancer or any other medical condition. The research evidence is limited, but without a good reason to think there might be benefits, the lack of evidence means no claims of benefits are justified. An absence of evidence, especially given nearly a century of claims for dramatic results, is more consistent with there being no benefit rather than with the product being a powerful treatment. Additional research could possibly show actual benefits in the future, but for now any use of this product is simply rolling the dice with your pet’s health.

Similarly, the evidence does not show whether or not the product is safe. Safety cannot be assumed in the absence of evidence, and it is more appropriate to assume there is some risk until safety is proven. Even individuals with cancer can have their lives made worse by the harm done by untested treatments, so there is currently no justification for inflicting this remedy on dogs and cats.

As usual, I will probably receive numerous anecdotes along the lines of “Well, I tried it and it worked for me/my dog.”  I have responded many times in detail as to why these are not useful in evaluating therapies like Essiac, so to save time I will list the articles that address this topic for anyone who thinks anecdotes contribute something to answering the questions of safety and efficacy:

Why We’re Often Wrong The Role of Anecdotes in Science-Based Medicine Why We Need Science: “I saw it with my own eyes” Is Not Enough

Don’t Believe your Eyes (or Your Brain)

Medical Miracles: Should We Believe?

Testimonials Lie

Alternative medicine and placebo effects in pets

Medical Practices Once Widely Accepted that Proved Ineffective or Harmful when Studied Scientifically




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14 Responses to Essiac Tea: More Snake Oil for Pets with Cancer

  1. linda pearson says:

    When conventional western medicine has no solutions and your pet is going to die anyway, what have you got to lose? Many have claimed their pets lived longer than expectations. There may be no scientific eveidence to support this but there is also no scientific evidence to refute it either.

  2. skeptvet says:

    There is plenty of evidence that unproven alternative therapies can do harm. There is even a study of an alternative treatment in people dying of incurable pancreatic cancer. The same “what do we have to lose?” argument was used to justify this study. It turned out that even people with this awful disease for which there is not effective conventional treatment died sooner and suffered more when managed with the alternative approach.

    The idea that grasping blindly at straws is good for our pets is mistaken. We can make them worse, and we can deprive ourselves and them of a chance to accept the end gracefully and find peace if we are constantly reaching for the next snake oil miracle.

  3. Diane Kalina says:

    My lab was diagnosed with an aggressive sarcoma when he was 5…they gave him 2 months at best. He was in bad shape and wouldn’t drink or eat anything and could even get up (we had to carry him outside to go to the bathroom). I gave him some essiac tea and he drank it! That was the only thing he would take. Within 3 weeks, he was like a new puppy, eating everything, drinking, running around like a puppy. I was AMAZING! I stopped giving it to him after a month and we noticed the tumor growing again. I started him back on the essiac tea and kept him on it for 6 months. He lived to be 14 and died from a car accident. It is definitely worth trying!

  4. skeptvet says:

    If only it were that easy. If only hearing stories like this and believing they show us the truth actually worked. Sadly, we tried that for most of human history, and we got terrible results. Science has given us far better improvements in our health that stories.

    Here are some other discussions of why anecdotes can’t be trusted:

    Why Anecdotes Can’t Be Trusted

  5. Me says:

    “There is no evidence from clinical trials to indicate that it is effective. No clinical trial has been carried out to assess its efficacy…”

    What’s wrong with this sentence?
    There is no evidence to indicate that it is effctive. Uh, maybe because there have been no trials to assess its efficacy.

  6. skeptvet says:

    Right, which means the appropriate answer to the question “Does it work?” is “We don’t know because there is no evidence.” Of course, this is not what people recommending or using it say. They say “It works because I’ve seen it work,” which is anecdotal and totally unreliable. There is also, of course, no reason to think it should work based on basic physiology and pharmacology, so I’d bet against it, but no definitive claim for or against has yet been proven, and that makes all the claims in favor of it invalid.

  7. Dogowner says:

    Me- the evidence from preclinical trials is “weak and inconclusive.” So prliminary evidence was collected, was looked at, and was so weak that no-one thought there was much point in going any further.

  8. jim Rocchio says:

    My cat Tigger was very sick with sores that would not heal on his skin. After many tests the vet found a large mass in his lung. He was diagnosed as lymphoma and Leukemia. I had to have surgery to remove his skin surrounding the sores. Using Essiac tea that I make from the herbs found on Amazon, have completely allowed the skin to heal. The tumor has also began to shrink. It has been two years. He was supposed to have passed by now. He was doing well and is a very happy kitty.

  9. skeptvet says:

    I’m glad your cat is well, but this story says nothing about the value of Essiac for all the reasons anecdotes simply can’t be relied on to identify what is safe and effective in medicine. Here are several articles (and a bit of humor) to illustrate some of the reasons why:

    Why Anecdotes Can’t Be Trusted

  10. Annie Ok says:

    For 48 years the “science” showed –“definitively”– that low-fat diets were the healthiest, that meat, eggs, and dairy were dietary killers. Everyone believed it. After all, these low-fat diets were promoted by the US government and by the medical establishment…and by the media. But….low-fat means high-carbohydrate. Forty years later, as a result of the fake “science”, our country suffers from an epidemic of obesity, diabetes and all of the diseases that cluster around a diet saturated in carbohydrates. The doctors who were conducting the clinical studies that refuted the party line were ignored. Why? Because they were not considered scientific enough. My point? Scientists have discredited science, and like the low-fat “scientists” you too could be wrong. In fact, there’s a 50-50-50 chance you are wrong. You have no proof that it does not work. So, all we have is anecdote, which is good enough for me. (Another “fake” science is human-caused global warming, but I won’t go there.)

  11. skeptvet says:

    That is a truly misleading oversimplification of the natural evolution of scientific knowledge concerning nutritional risk factors for disease. “Fat is bad” was a popular oversimplification of science just as “carbs are bad and fat is good” is a popular oversimplification of complex and nuanced information. The fault here is not in science but in the human need to oversimplify and ignore nuance and uncertainty. The science that suggested high-fat diets increase the risk of obesity and cardiovascular disease wasn’t “wrong.” We now know more about the role of various kinds of fats in the pathophysiology of disease, but anyone who has decided they can now eat nothing but bacon and eggs and live forever is still mistaken. Similarly, the folks now blaming grains and carbs for every ill are misrepresenting science, and when fads like kept and gluten free turn out not to be miraculous life-savers, folks like you will likely point to that and say “see, science was wrong” even though science didn’t make those claims in the first place.

    As for “anecdotes are good enough for me,”that blithely ignores what a dismal failure anecdotes have been throughout human history and how dramatically better our lives our since we started paying more attention to science. Anecdotes would still have you going to a barber for blood-letting and a purgative for your pneumonia, from which you would likely. die, rather than getting a diagnosis and treatment that could save you. Your anti-science, my-gut-knows-better narrative is a sadly widespread and deeply mistaken view that leads to much unnecessary suffering.

  12. Linda Nicholson says:

    Does it work ? Well…. I have given it to 12 people ( learned of it when my hubby was ill ) 4 of the 12 terminal. Well all 4 are thriving. The other 8 doing great . Not 1 month later. Longest is 8 years later. Snake oil my ass !!!
    Cancers ranged from pancreatic to colon to ovarian. All followed doctors protocol plus essiac. Except one who did not want to do chemo for her breast cancer. She is doing very well. I buy from a reliable source which I feel is key. Never had the need to give to a dog.

  13. Vb says:

    Saved my dogs life. Recersed osteosarcoma. She has two disgnosis of cancwr from different vets. She lived and her case was researched by university of illinois vet school. My vet was blown away. It works

  14. skeptvet says:

    I’m glad your pet is doing well, but such anecdotes don’t, unfortunately, prove anything. Here area number of articles (and a little humor) looking at why:

    Why Anecdotes Can’t Be Trusted

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