Essiac is a mixture of roots, bark and leaves that you boil to make a drinkable liquid. Other Essiac products are known as Flor-Essence. There is no scientific evidence to use it as a treatment for cancer.


  • Essiac is a mixture of herbs from Canada
  • There is no scientific evidence to support its use as a treatment for cancer
  • Essiac can have side effects

What is essiac?

Essiac is a herbal remedy from Canada.

It has 4 ingredients:

  • burdock root
  • sheep sorrel
  • slippery elm
  • Indian Rhubarb root

A modified Essiac product called Flor Essence also includes:

  • watercress
  • blessed thistle
  • red clover
  • kelp

A Canadian nurse called Rene Caisse created Essiac. She named the remedy after herself. Essiac is her surname spelled backwards.

A commercial company now owns Essiac. Essiac is a registered trademark. Essiac Canada International is the only manufacturer that has rights to Rene Caisse's original formula of herbs.

Why people with cancer use it

Websites promote Essiac as a cure or treatment for cancer. But there is no scientific evidence to prove that Essiac can do this.

Some people call Essiac 'the tea of life' and claim it is a miracle cure for cancer. There have been reports of cancers completely disappearing after taking Essiac.

But, in many of these reports, detailed information on the diagnosis was missing. Or what types of conventional cancer treatments doctors used as part of the treatment.

Conventional treatments are more likely to be the reason for the cancer disappearing.

A laboratory study on mice showed that Essiac killed certain cancer cells. Researchers linked it to a chemical found in rhubarb. But we need studies in humans before we can say that Essiac can be used as a cancer treatment.

Some people believe that alternative or complementary therapies can boost the immune system. That way it helps to fight their cancer.

A laboratory study on Essiac showed that it had antioxidant features. That means it can protect cells from damage. It also showed that it had some effect on the immune system. But there is not enough scientific evidence to say it can work as a treatment for cancer.

A study on mice in 2007 showed that Essiac did not affect the immune system.

We need more evidence from research to be sure exactly how Essiac might affect the immune system.

Some people take Essiac because they think it helps to:

  • relieve pain
  • shrink tumours
  • reduce weight loss (cachexia) in advanced cancer
  • improve health, energy levels and wellbeing
  • detoxify and cleanse the body

Laboratory studies showed that Essiac could kill certain cancer cells. But this was when researchers used a high concentration of Essiac. The researchers suggested more research. In another study Essiac caused breast cancer cells to grow.

Researchers also did a retrospective study on people with breast cancer. It showed that Essiac did not improve quality of life or mood.

Your doctor might tell you there are no further conventional cancer treatments to cure your cancer. But there are treatments to control your symptoms.

The news that your cancer can’t be cured can be difficult to accept. So, it isn’t surprising that some people consider using alternative therapies.

It is understandable that you might hope that Essiac will help you to live longer.

How you have it

Essiac is available as:

  • a powder – you make this into a tea that you drink
  • a liquid (extract) – that you can mix with water
  • capsules
  • dry versions
  • drops

The manufacturers advise you not to eat 1 hour before or after taking Essiac.

Using Essiac safely

The makers of Essiac and Flor essence say that Essiac can be used alongside cancer treatment. But some websites advise that you stop your cancer treatments while you have it.

Stopping cancer treatment such as cancer drugs, chemotherapy and radiotherapy could be very harmful to your health. Do not replace your conventional cancer treatment with any type of alternative cancer therapy.

It is understandable that you and the people who care about you might want to try something if you think it might help. Only you can decide whether or not to use an alternative cancer therapy such as Essiac.

Remember that Essiac:

  • is not accepted or licensed as a drug
  • is usually sold as a nutritional supplement
  • has no scientific evidence to support the claims made by its promoters

Side effects

The only side effects linked to Essiac are nausea and vomiting.

The makers say that it might cause:

  • swollen glands
  • flu like symptoms
  • headaches
  • skin redness and inflammation
  • passing urine or opening your bowels more often than usual

In 1 case report a woman had a lack of appetite. She also felt sick, had tiredness, and abdominal pain after taking Essiac tea for 6 months. Her symptoms got better when she stopped taking the tea.

Another case report suggests that Essiac may slow down the rate at which your body breaks drugs down. This can mean that some drugs will be more potent or that their effects last longer in your body. The case report suggests that Essiac may block liver enzymes called cytochrome p450. These enzymes are important in getting some cancer drugs out of your system.

Talk to your cancer specialist about this if you are thinking of taking Essiac.

Research into Essiac in cancer treatment

Most of the websites that promote Essiac use opinions not backed up by research. Some of this information is often anecdotal evidence. That means it is based on hearsay.

The Memorial Sloan Kettering Cancer Centre tested Essiac in the laboratory. They found it had no anti-cancer features.

The National Cancer Institute (NCI) in the U.S tested Essiac several times. Their testing found that Essiac had no anti-cancer effects. One study in 2006 found that when Essiac was added to breast cancer cells in test tubes, it stimulated the cancer cells to grow.

In 2009 researchers reviewed all studies into Essiac and Essiac preparations. They found there were no well carried out clinical trials to show that Essiac can help with cancer. 

The CAM-Cancer organisation reviews scientific research evidence. In 2011, they looked at all the reviews about Essiac and Flor Essence. They couldn’t find any well carried out clinical studies. They said that some of its ingredients could cause harm.

We need well designed clinical trials to test Essiac and its herbs. Only then will we know if Essiac works or is safe for people with cancer.

How much it costs

Be cautious about believing information or paying for any alternative cancer therapy on the internet.

A word of caution

It is understandable that you might want to try anything if you think it might help treat or cure your cancer. Only you can decide whether to use an alternative cancer therapy such as Essiac.

You could harm your health if you stop your cancer treatment for an unproven treatment.

Some websites might promote Essiac as part of treatment for cancer. But no reputable scientific cancer organisations support any of these claims.

  • Flor-Essence® herbal tonic does not inhibit estrogen receptor negative mammary tumor development in a transgenic mouse model

    L Bennett and others

    Journal of Complementary and Integrated Medicine. 2011 January; 8: 10.2202/1553-3840.1157

  • Essiac: systematic review by the natural standard research collaboration

    C. Ulbricht and others

    Journal of the Society for Integrative Oncology, Spring 2009, Vol 7 (2): 73-80.

  • Essiac and Flor-Essence herbal tonics stimulate the in vitro growth of human breast cancer cells

    K.S Kulp and others

    Breast cancer research and treatment, August 2006. Vol 98, (3): 249-59. 

  • Essiac/Flor Essence (PDQ®)–Health Professional Version

    National Cancer Institute (NIH)

    Accessed February 2019

  • Essiac tea: Scavenging of reactive oxygen species and effects on DNA damage

    S Leonard and others

    Journal of Ethnopharmacology 103 (2006) 288–296

  • The chemistry and biological activity of herbs used in Flor-Essence herbal tonic and Essiac

    C.Tamayo and others

    Phytotherapy Research, Feb 2000. Vol 14, (1):1-14. 

  • The information on this page is based on literature searches and specialist checking. We used many references and there are too many to list here. If you need additional references for this information please contact with details of the particular issue you are interested in.

Last reviewed: 
26 Sep 2022
Next review due: 
26 Sep 2025

Related links