Written by Luc Geeraert and the CAM-Cancer Consortium.
Updated July 9, 2014

Intravenous high-dose vitamin C

Abstract and key points

  • Vitamin C (L-ascorbate or L-ascorbic acid) has been used in the treatment of cancer patients. Intravenous administration of vitamin C is used to attain pharmacologic concentrations.
  • Anti-cancer activity of high intravenous doses of vitamin C has not been confirmed in clinical trials.
  • There is limited evidence indicating that high-dose intravenous vitamin C might improve the quality of life of patients with advanced cancers.
  • High intravenous doses of vitamin C are generally safe, causing only minor side effects, but are contraindicated in people with renal disease or glucose 6-phosphate dehydrogenase deficiency. They may interact with conventional anti-cancer therapies. 

Physiological concentrations of vitamin C (L-ascorbate or L-ascorbic acid) in the body are controlled through intestinal absorption, tissue accumulation, and renal reabsorption and excretion. Therefore, intravenous administration is used to achieve pharmacologic doses.

In the context of cancer, high-dose intravenous vitamin C (> 0.5 g per kg body weight) is claimed to have several effects: a) cytotoxicity for cancer cells, but not for normal tissue, b) improved quality of life for cancer patients, c) protection of normal tissues from toxicity caused by chemotherapy, and d) reinforcement of the action of radiation and some types of chemotherapy.

A limited number of Phase I clinical trials, including only one controlled trial, confirm the non-toxic character of the treatment, and give some indications that the treatment may improve quality of life, but do not suggest distinct anti-cancer effects. Several case reports argue for a positive effect on survival time, even reporting cancer remission, and improved quality of life.

High-dose vitamin C is essentially non-toxic. Reported side-effects are minor if patients are adequately screened for renal disease and glucose 6-phosphate dehydrogenase deficiency, and when doses are gradually increased with careful monitoring of the patient. Vitamin C might reduce the therapeutic response to some conventional anti-cancer therapies, but may act synergistic with other conventional therapies.


Luc Geeraert, CAM-Cancer Consortium. Intravenous high-dose vitamin C [online document]. http://www.cam-cancer.org/The-Summaries/Other-CAM/Intravenous-high-dose-vitamin-C. July 9, 2014.

Document history

Most recent update and revision in July 2014 by Luc Geeraert.

Fully updated and revised in October 2012 by Luc Geeraert.

Summary first published in February 2011, authored by Luc Geeraert.


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