Essiac Side Effects

When we think of side effects we usually think in terms of possible harmful or unintended consequences of taking a certain pharmaceutical drug.  These side effects can affect people differently from person to person, are often debilitating and sometimes lethal.

Herbs, on the other hand, are rarely lethal or debilitating.  Compared to dangerous pharmaceutical drugs healing herbs are much safer and more effective in achieving good health.  Generally speaking, herbs help heal the body while Big Pharma drugs "treat" symptoms.  Doctors often prescribe more drugs to treat the unintended, harmful side effects of a drug and this can end up damaging one's health even further.

What some people would call Essiac "side effects" are actually Nature's processes in healing the body.  "Their fruit will serve for food and their leaves for healing.”  Ezekiel 47:12. 

In May of 1974 Rene Caisse wrote the following words to Dr. Chester Stock: 

"It took years to find out the one herb that actually worked on the growth itself [Sheep Sorrel].  The other herbs [burdock, slippery elm & turkish rhubarb]  I used to purify the blood and throw off any infection thrown off by the malignant growth as it regressed." 1

"The research showed Sheep Sorrel, the most acidic ingredient at pH 4.5, to be the one herb that had a directly destructive effect on cancerous cells.  All the initial experiments were carried out on laboratory mice:  'We found that on mice inoculated with human carcinoma, the growth regressed until it was no longer invading living tissue after nine days of Essiac experiments." 2 

Rene Caisse described this process in detail in the following three paragraphs: 

"Most importantly, and this was verified in animal tests conducted at the Brusch Medical Center and other laboratories, it was discovered that one of the most dramatic effects of taking this remedy was its affinity for drawing all the cancer cells which had spread back to the original site at which point the tumor would first harden, then later it would soften, until it vanished altogether or more realistically, the tumor would decrease in size to where it could then be surgically removed with minimal complications.

"In certain cases and at certain stages of the disease, the cancer would act as if it were 'coming to a head', similar to an abscess. It would then break down and slough away.  These people all reported that when the mass breaks, it isn't like pus but like a cottage cheese substance that comes away.  Still other types will enlarge until the mass is localized, then loosen and reduce in size until there is nothing left, having been absorbed into and carried off by the blood stream and body waste.  

"I found also that no matter where the malignancy may be in the human body, surgery would be much more successful after six to eight treatments of Essiac, followed by further treatments once a week after the operation for a period of three months; then there would be no recurrence of the tumor.  In the case of breast cancers, the primary growth will usually invade the mammary gland of the opposite breast or the auxilla (armpit), or both.  My treatment, I found, reduced the secondary growth into the primary mass, enlarging it for a time.  When it became localized, it was encapsulated and could then be removed without danger of recurrence.  In one instance, a patient with breast cancer was instructed by her doctor to have six Essiac treatments before undergoing surgery.  After the fifth treatment, however, the cancer disappeared, with no recurrence." 3

"It is very important to use the dosage as recommended, which was based on more than 54 years' experience.  Rene was very concerned about this, which is why she personally administered the dose to her patients.  The herbs are very potent, and in particular Sheep Sorrel can have the effect of enlarging the tumor too quickly, so that it may burst, or a vital organ may be blocked because of its increase in size.  Sometimes the tumors will soften, dissolve into small pieces and be eliminated through the bowel or the urinary tract.  Cancer growths in the breast have been known to become encapsulated within six weeks to three months, and can then be removed surgically with little danger of metastasising in the future.  Cancers of the oesophagus have also become encapsulated and removed cleanly and safely by surgery." 4 

"Depending on special circumstances, very occasionally in her later years, she would sometimes advise an initial dose of one fluid ounce twice daily for the first five, ten or (rarely) thirty days before reducing to one fluid ounce a day.  Rene was always very particular about this because she was aware that sometimes, when patients first began taking the Essiac formula, their tumours might enlarge suddenly as though they were gathering back the cancerous cells that had metastasised.  When that happened, she either gave lighter doses or stopped treatment altogether for a time, to prevent a vital organ from becoming blocked.  It all depended on the nature and position of the tumour.  For example, primary brain tumours rarely metastasise and we have had no reports of this type of swelling when taking Essiac in these cases.  Essiac should never be administered intravenously.  During the early days of Rene's pioneering research, she found that only Sheep Sorrel could be injected intramuscularly as an individual herb." 4

*It should be noted that Nurse Caisse often treated cancer patients with sheep sorrel solution injections in conjunction with the tea, which would produce more dramatic and quicker results than the tea alone.  The injections could understandably create a situation in some cases where a vital organ might be blocked if the tumor rapidly increased in size.  However, sheep sorrel injections are no longer used.  She also used other herbs, too, and sheep sorrel root was a necessary part of the Essiac formula to achieve the results she achieved at the Rene M. Caisse Cancer Clinic.

According to the authors of ESSIAC ESSENTIALS [p. 45], the following reactions may occur when treating cancer that demonstrate how Essiac works.  These are the intended effects, not "side" effects, of using Essiac tea as a remedy for cancer.  People without cancer do not have to be concerned about these effects since they do not have cancer or cancerous tumors.  Chemotherapy, for example, does have some very serious "side effects" which are printed on the black box warnings.  Chemotherapy can actually cause cancer as one of its side effects!  Chemotherapy can cause death as well amongst its many harmful side effects!  Thankfully, herbal medicine is much safer and reactions, if any, are usually mild and not life threatening.


a)  swelling--occurs when metastasised cells gather into the primary tumour.

b) cottage cheese effect--resembling curds and clear liquid, occurs as the cancer breaks up and discharges from either the body orifices or from localised cysts or swellings.  A jelly-like substance can also be discharged or coughed up from the lungs.

c) more frequent passing of urine/defecation and other inexplicable discharges--occurring as the body detoxifies.  If the symptoms are severe, with related nausea and pain, stop taking the formula for a few days until all the symptoms have subsided.  When you start drinking it again, take half an ounce every other day, gradually resuming the original dosage.  Remember that all diseases have a life cycle and a rhythm of their own, so follow your own judgement according to what your body is telling you about the dosage it needs.

d) aching 'on site' and headaches, linked to the detoxification process, have been noted as sometimes occurring when taking Essiac after surgery.  Treat as for (c) and drink more water to flush out toxins from the body.

e) fever or chills--sometimes occurring when the Essiac starts working directly on the cancerous cells. 5

It should be noted that these effects may sometimes occur in people with cancer.  People without cancer can drink Essiac tea without concern for these possible effects.  In fact, the grassroots reports (aka "anecdotal evidence") of Essiac tea use by people without cancer reveals it is a viable cancer preventive as well as a foundational health tonic. 

This phenomenon begs the question:  Why suffer through the hell of chemo, radiation, surgery and astronomical medical bills when one can prevent cancer in the first place with a cup of Essiac tea on a fairly frequent basis coupled with a healthy diet and exercise? 

Of course, Essiac tea cannot reverse the consequences of eating over-processed foods, many of which contain cancer-causing substances.  Therefore, the best health insurance one can obtain is a diet focusing on whole, organic foods while avoiding cancer-causing substances in over-processed foods, processed meats, fast foods, etc. 

The word "organic" in this sense means that the plants are not sprayed with cancer-causing herbicides or pesticides and are not overly processed.  Raw foods are essential to a healthy diet and have been shown to stop cancer (see Dr Max Gerson's diet) and diabetes (see Dr Gabriel Cousen's diet).  The "Eating Right for Your Blood Type" research by Dr Peter D'Adamo is a very helpful tool to find which foods are highly beneficial and which foods are detrimental to one's blood type.6

More information from Ingri Cassell of

For most people, consuming Essiac Tea is considered safe with minimal side effects, except for those who are taking pharmaceutical medications. Although some would caution pregnant and nursing mothers from drinking Essiac Tea, we have found that none of the ingredients are specifically harmful if taken during pregnancy or while nursing. People react differently to pharmaceuticals and dietary supplements. While some people experience adverse side effects, others experience no problems or side effects at all. Negative side effects of taking the tea are possible, but not probable. As with any herbal supplement, you may want to consult with your naturopath before using Essiac Tea. Based upon your health history, your naturopath may have a good reason why you should not drink Essiac Tea at this time.

We highly recommend that anyone drinking Essiac Tea for the first time start out with very small doses and work up to the recommended amount of 2 oz. of the concentrated tea, with 8 oz. of boiling water added to each dose, twice a day on an empty stomach.

Sheila Snow wrote in her book Essence of Essiac, page 48:

Here are three possible causes of adverse reactions:

  • A full stomach of undigested food or consuming beverage just before taking the remedy, especially tea or coffee.
  • As waste materials build up in the body, it attempts to eliminate them all at once. This could create extreme discomfort in the digestive tract, occasionally to the point of vomiting.
  • A tumor may increase in size (as metastasized cells are gathered to original site) and could cause a blockage in some vulnerable area of the body before it softens and reduces in size.

“When any discomfort occurred, Rene always cautioned her patients to stop taking the decoction for several days until they felt better. Then they were told to begin again with just half an ounce every other day and gradually to increase the dose to one ounce each day. This usually corrected the problem.”

How To Avoid Side Effects From Drinking Essiac Tea

  1. Start with a small dose (½ an ounce once a day) to see how your body reacts.
  2. Take the tea on an empty stomach. First thing in the morning and an hour before bed are good times.
  3. Drink plenty of water to aid in the removal of toxins.
  4. Stick to a reasonable dose, paying attention to how your body responds to each increase in the amount Essiac Tea consumed. Most Essiac Tea side effects are caused by taking too much. It is ultimately up to you to decide what is best for your body to heal.

Water Intake

Other side effects, such as diarrhea, a mysterious lower-back kidney ache, flu-like symptoms or upset stomach may be caused by using too high of a dose and not drinking enough water. Anyone taking Essiac Tea should increase their water intake, due to its detoxification properties, which cause the release of toxins from tissues and blood, excreting them via the intestinal and urinary tracts. The toxins must be diluted as they are released from the body tissues or they become concentrated, causing stress on the liver and kidneys which can lead to headaches, nausea and a general feeling of ill health.

We recommend that you drink a minimum of half your body weight in ounces of purified water daily in addition to the Essiac Tea. Dehydrating drinks such as soda pop, black tea, coffee, and juice do not count in that amount. In fact, you should completely avoid drinking soda pop, coffee and alcohol while drinking Essiac Tea. See Why to Drink More Water

See also The Importance of Colon Cleansing


Diabetics who are insulin dependent may need to adjust their dosage, as well as those on anti-diabetes medications. We recommend that diabetics monitor their blood sugar closely while on this tea. Some of the constituents in this tea are known to affect the way glucose and insulin are taken up by the cells and utilized. Most people find they need less medication while taking this tea. While this is not always the case, it would be wise to monitor your blood pressure and blood sugar while taking Essiac consistently.

Monitoring is critical because blood sugar may drop too low, or your blood sugar might shoot up too high, according to this email comment:

“You need a stronger warning for diabetics. I have been a well regulated insulin dependent diabetic for over fifty years. I followed all directions for making and drinking at proper time. I got very nauseated and my blood sugar shot up to 284 four hours later.”

This person had decided to take our recommended dosage of 2 oz. twice a day (4 oz. of the decoction twice a day). Apparently his blood sugar shot up after the first 2 oz. dose.

This is worth repeating…. “When any discomfort occurred, Rene always cautioned her patients to stop taking the decoction for several days until they felt better. Then they were told to begin again with just half an ounce every other day and gradually to increase the dose to one ounce each day. This usually corrected the problem.”

We advise diabetics to start with a tiny dose of ½ oz. tea (1 Tablespoon) every other day before gradually increasing the dose to ½ oz. tea per day ( ½ Tablespoon twice a day) to 1 oz. tea per day (1 Tablespoon twice a day). Monitoring should reveal whether blood sugar levels go up or down.

Kidney Disease, Kidney Stones

Some sources advise not taking Essiac Tea if you have kidney disease or are prone to kidney stones because of the oxalic acid in sheep sorrel. Although using a small dosage amount shouldn’t cause problems, people with kidney disease should consult with their naturopath before using Essiac Tea.

Allergic Reactions

With the increase in allergies today, it has been suggested that you may be allergic to one (or more) of the Essiac Tea herbs if you develop an itchy rash anywhere on your body, or you come down with a sudden case of hay-fever symptoms with sneezing, runny nose and eyes. According to noted researcher and author Mali Klein, who happens to be slightly allergic to sheep sorrel, she has warned others that they, too, may be allergic to sheep sorrel. We strongly suggest that you do a series of liver cleanses until you are able to reduce your allergic reactions before attempting to retry consuming Essiac Tea.

If you have NO allergic reactions from taking the tea, we recommend that you stick to a reasonable dosage ranging from a minimum of 1 oz. per day as a “tonic” to a maximum of no more than 2 oz. of the decoction twice a day for “illness”.7


1.  ESSIAC:  Secrets of Rene Caisse's Herbal Pharmacy, p. 23

2.  ESSIAC:  Secrets of Rene Caisse's Herbal Pharmacy, p. 23, 24







The information on this page and on this website is for educational, historical and general information purposes only and should not be construed as medical advice.

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