Vitamin C (L-ascorbic acid or ascorbate) is a nutrient we must get from food or dietary supplements since the body cannot make it. Vitamin C is an antioxidant – it helps prevent oxidative stress and works with enzymes to play a key role in making collagen.

A severe lack of vitamin C in the diet causes scurvy, a disease with symptoms of extreme weakness, dry skin, lethargy, easy bruising, and bleeding.

A History of the Medical Use of High-Dose Vitamin C

High-dose vitamin C has been studied as a treatment for patients with cancer since the 1970s. A Scottish surgeon named Ewan Cameron worked with Nobel Prize-winning chemist Linus Pauling to study the possible benefits of Vitamin C Therapy in clinical trials of cancer patients in the late 1970s and early 1980’s.

Surveys of healthcare practitioners at United States CAM conferences in recent years have shown that high-dose IV vitamin C is frequently given to patients as a treatment for infections, fatigue, and various cancers, including breast cancer.

High-Dose Vitamin C as a Complementary Therapy

vit c drip

More than fifty years ago, a study suggested that cancer was a disease of changes in connective tissue caused by a lack of vitamin C.

In the 1970’s, it was proposed that high-dose ascorbic acid could help build resistance to disease or infection, and possibly treat cancer.

Later studies showed that the levels of vitamin C that collect in the bloodstream depend on how it is taken.

When taken by intravenous (IV) infusion, vitamin C can reach much higher levels in the blood than when taken by mouth. Studies suggest that these higher levels of vitamin C may cause the death of cancer cells in the laboratory.


Both Laboratory studies and Animal Studies have been done to find out if high-dose vitamin C may be useful in preventing or treating cancer. The anticancer effect of vitamin C in different types of cancer cells involves a chemical reaction that makes hydrogen peroxide, which may kill cancer cells.

Some of the animal studies showed that

  • High-dose vitamin C blocked tumour growth in animal models of pancreatic, liver, prostate, sarcoma, and ovarian cancers and malignant mesothelioma.
  • Vitamin C made a type of light therapy more effective when used to treat mice injected with breast cancer cells.
  • A study in a mouse model of ovarian cancer showed that combining intravenous high-dose vitamin C with the anticancer drugs carboplatin and paclitaxel made them more effective in treating ovarian cancer.

Several studies of high-dose vitamin C in patients with cancer have been done in recent years, including the following:

  • A study of IV vitamin C and high doses of vitamin C taken by mouth was done in patients with cancer that could not be cured. Vitamin C was shown to be a safe and effective therapy to improve quality of life in these patients, including physical, mental, and emotional functions, symptoms of fatigue, nausea and vomiting, pain, and appetite loss.
  • In a 2014 study of 27 patients with advanced ovarian cancer, treatment with chemotherapy alone was compared to chemotherapy along with IV vitamin C. Patients who received IV vitamin C along with chemotherapy had fewer serious side effects from the chemotherapy.
  • In a small study of 14 patients with advanced pancreatic cancer, IV vitamin C was given along with chemotherapy and treatment with a targeted therapy. Patients had very few bad side effects from the vitamin C treatment. The nine patients who completed the treatment had stable disease as shown by imaging studies
  • Patients with acute myeloid leukaemia, refractory metastatic colorectal cancer, or metastatic melanoma treated with IV vitamin C combined with other drugs had serious side effects and the disease got worse.

How is High-Dose Vitamin C Administered?

oranges and lemons

Vitamin C may be given by intravenous (IV) infusion or taken by mouth, although much higher blood levels are reached when given intravenously.

We can get a lot of vitamin C from various fruits, especially citrus fruits such as lemons, limes, and oranges.

Other foodstuffs that are high in Vitamin C, which most individuals are totally unaware of, include Chili peppers, Red bell peppers, Cauliflower, Brussels sprouts, Pineapple, Kale, Broccoli, Papaya, Green bell peppers, Strawberries, Kiwi Fruit, and Mango.

We can also take vitamin C tablets, but the amount of Vitamin C that we can get from those sources is not as high as what one can get with an intravenous (IV) infusion.

Side Effects or Risks

Intravenous high-dose ascorbic acid has caused very few side effects in clinical trials. However, high-dose vitamin C may be harmful in patients with certain risk factors:

  • Kidney failure has been reported in patients with a history of kidney disorders after ascorbic acid treatment. Patients with a tendency to develop kidney stones should not be treated with high-dose vitamin C.
  • Case reports have shown that patients with an inherited disorder called G-6-PD deficiency should not be given high doses of vitamin C, due to the risk of haemolysis (a condition in which red blood cells are destroyed).
  • Since vitamin C may make iron more easily absorbed and used by the body, high doses of the vitamin are not recommended for patients with hemochromatosis (a condition in which the body takes up and stores more iron than it needs).

Some drug interactions have been reported from combining high-dose vitamin C with anticancer drugs in laboratory and animal studies; No clinical trials have been done to further research these drug interactions in humans:

  • Combining vitamin C with an anticancer drug called bortezomiba, a targeted therapy that blocks several molecular pathways in a cell causing cancer cells to die, was studied in cell cultures and in animal models. Several studies showed that vitamin C given by mouth made bortezomib less effective, including in multiple myeloma cells. A study in mice transplanted with human prostate cancer cells, however, did not show that giving the mice different doses of vitamin C by mouth made bortezomib therapy less effective.
  • An oxidised form of vitamin C called dehydroascorbic acid has been studied in cell cultures and in animals with tumours. Several studies found that high doses of dehydroascorbic acid can interfere with the anticancer effects of several chemotherapy drugs. Dehydroascorbic acid is found in only small amounts in dietary supplements and in fresh foods.

As with any other complementary therapy, consult with your oncologist before embarking on any other type of therapy or medication and also inform the therapist of your cancer status and what medications you are taking etc.


Please note that the Little Fighters Cancer Trust shares information regarding various types of cancer treatments on this blog merely for informational use.

LFCT does not endorse or promote any specific cancer treatments – we believe that the public should be informed but that the option is theirs to take as to what treatments are to be used.

Always consult your medical practitioner prior to taking any other medication, natural or otherwise.