Intravenous vitamin C


As many of you know, I am a proponent of using high doses of intravenous vitamin C in certain cancer patients, patients with chronic infections and immune deficiencies. Intravenous vitamin C is one of the more widely available treatments in Vancouver and Richmond, done by many naturopathic doctors.


High doses of vitamin C given intravenously (as opposed to the 10 grams given orally and studied in the past at the Mayo Clinic) may have the interesting effect of being an oxidative treatment.  We all know that vitamin C taken orally acts as an antioxidant, but an important point is that very high doses given intravenously, usually between 25-100 grams, has a pro-oxidative effect.  The mechanism involves the generation of hydrogen peroxide within the tissues that accumulate the vitamin C.  

Semin Radiat Oncol. 2019 Jan;29(1):25-32. doi: 10.1016/j.semradonc.2018.10.006.

Pharmacological Ascorbate as a Means of Sensitizing Cancer Cells to Radio-Chemotherapy While Protecting Normal Tissue.

Schoenfeld JD1, Alexander MS2, Waldron TJ3, Sibenaller ZA1, Spitz DR3, Buettner GR3, Allen BG3, Cullen JJ4.

Author information


Chemoradiation has remained the standard of care treatment for many of the most aggressive cancers. However, despite effective toxicity to cancer cells, current chemoradiation regimens are limited in efficacy due to significant normal cell toxicity. Thus, efforts have been made to identify agents demonstrating selective toxicity, whereby treatments simultaneously sensitize cancer cells to protect normal cells from chemoradiation. Pharmacological ascorbate (intravenous infusions of vitamin C resulting in plasma ascorbate concentrations ≥20 mM; P-AscH-) has demonstrated selective toxicity in a variety of preclinical tumor models and is currently being assessed as an adjuvant to standard-of-care therapies in several early phase clinical trials. This review summarizes the most current preclinical and clinical data available demonstrating the multidimensional role of P-AscH- in cancer therapy including: selective toxicity to cancer cells via a hydrogen peroxide (H2O2)-mediated mechanism; action as a sensitizing agent of cancer cells to chemoradiation; a protectant of normal tissues exposed to chemoradiation; and its safety and tolerability in clinical trials.

One postulated mechanism of this formation involves vitamin C displacing iron from its carrier protein, with the subsequent intracellular generation of hydrogen peroxide.  This is selectively toxic to cancer cells because they lack an enzyme that other healthy cells have in abundance: catalase.


Catalase is one of the fastest enzymes ever studied.  Its’ job is to do the following conversion:


2H2O2 (hydrogen peroxide) -->  2 H2O (water) + O2 (oxygen)


The products water and oxygen are of course harmless.  If this reaction does not occur efficiently theoretically due to lack of the catalase enzyme (ie in cancer cells) the hydrogen peroxide can react with the displaced iron and create an excess of free radicals.  These free radicals then stimulate apotosis or cell suicide in the cancer cells.  


The IV treatments are generally painless, and while very safe and well tolerated, can carry some risks as with any IV procedure. They are a slow IV drip over 45 minutes to 2-3 hours depending on the dose given.  


In some of the articles, the study’s author makes a clear distinction from the generation of tissue peroxide and giving hydrogen peroxide intravenously.  This is an important distinction as the mechanism of action is different.  Intravenous dilute hydrogen peroxide has also been used as an adjunctive cancer treatment, but the peroxide is reacted with immediately in the blood by catalase.   Instead, the effect is theorized to be an immune system stimulation, with the generation of cytokines (chemicals that act on the immune system) that provoke a redirection of resources to focus on the fighting of the immune system.  It is the same mechanism that applies to ozone therapy.  In these oxidative therapies, the generation of the chemicals interferon gamma and tumor necrosis factor alpha.  With vitamin C, it seems that we can get similar releases of chemicals, but only if the immune cells are already stimulated.


Dosages used in intravenous vitamin C


In my Vancouver and Richmond patients, many have reported that they have received intravenous vitamin C at other clinics, usually in dosages ranging from 12.5 to 50 grams. It is similar in my office.


Frequency of use


Most of the studies on vitamin C are "test tube"studies, but they are markedly positive, when studied alone against cancer and also when studied with a variety of chemotherapy agents. It is always best to check with your naturopathic doctor and oncologist regarding the use of vitamin C during chemotherapy. Clinician experience usually sets the frequency of intravenous vitamin C at 2-3 times per week to start, and then reduction in frequency.

Side effects during intravenous vitamin C


  • nausea (prevented by eating during and before treatment)

  • thirst

  • frequent urination

  • Very Rare: risks of vein irritation, volume overload, infection, clots.