Written by Helen Cooke, Helen Seers and the CAM-Cancer Consortium.
Updated February 8, 2017

Gerson therapy

Is it safe?

There is concern that people may choose to use this regime as an alternative to chemotherapy, thereby avoiding mainstream treatment. The Gerson Institute does not recommend the use of chemotherapy with the diet since the chemotherapy is seen as a poison in the body, and during detoxification the body would find difficulty in dealing with the level of toxins.1 Several aspects of the Gerson therapy itself have been seen as possible causes of adverse effects. These include: coffee enemas,17 the restrictive nature of the diet, thyroid supplements and also the now disused practice of drinking liver juice. The American Cancer Society and the US National Cancer Institute, do not recommend the use of the Gerson therapy, warning that patients should not turn away from mainstream therapy to rely only on this alternative approach.

Adverse effects

Coffee enemas

Serious illnesses, colitis, electrolyte imbalance and even death have been associated with the use of coffee enemas.17 However, these incidences have not been reported in patients undergoing the Gerson treatment at the clinic. In two isolated cases reported two women in Seattle (one with cancer) died due to the enemas removing potassium from the body leading to serious electrolyte imbalance. In either case enemas were used more frequently than is recommended by the Gerson therapy guidelines. It is thought that continued home use of enemas may weaken the colon’s natural function leading to problems such as constipation and colitis.17

Restricted diet

The use of a restricted detoxifying metabolic diet alongside enemas may cause an “inflammatory reaction” which is believed to be part of the healing process.10 Negative symptoms of this inflammatory reaction include dehydration, nausea, diarrhoea, flu-like symptoms and death.18


There are safety concerns over the excessive ingestion of potassium. Those with too much potassium in their blood may suffer from hyperkalemia; symptoms include muscle numbness, tingling, abnormal heart rhythm, paralysis and possible heart failure.19

Calves liver juice

The drinking of calves’ liver juice was removed from the Gerson therapy guidelines in 1989 after a history of it being associated with infection with Campylobacter fetus subspecies fetus.20 An outbreak of this bacterial infection was seen in 1981 which killed nine cancer patients who were thought to be using the Gerson treatment.20,21 After learning of this outbreak staff at the Gerson Institute worked with those at the clinic in Mexico to ensure patient safety and by 1989 the policy of drinking liver juice was altered to receiving crude liver extract injections.


Due to the complex nature of the therapy many interactions with other drugs may occur.


The National Cancer Institute 22 urges patients to not seek treatment from the Gerson clinic due to a lack of evidence of the anti-cancer effects and also potential hazards associated with the therapy.


Helen Cooke, Helen Seers, CAM-Cancer Consortium. Gerson therapy [online document]. http://cam-cancer.org/The-Summaries/Dietary-approaches/Gerson-therapy. February 8, 2017.

Document history

Assessed as up to date in February 2017 by Barbara Wider
Assessed as up to date in April 2016 by Barbara Wider.

Assessed as up to date in January 2015 by Barbara Wider.
Assessed as up to date in August 2013 by Barbara Wider.
Most recent update and revision in September 2012 by Helen Cooke.
Fully revised and updated in August 2011 by Helen Cooke.
Fully revised and updated in November 2009 by Helen Cooke.
Summary first published in July 2005, authored by Helen Seers and Helen Cooke.


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