Vitamin C, intravenous
Also called: IV vitamin C, pharmacological ascorbate.
Last reviewed 2026-09-16. How this works.
Treating cancer Grade D
No human evidence of benefit, or none that survived testing.
Given by drip, vitamin C does reach the levels the lab work needs, but no trial has tested if that helps.
The concentration is reachable. Nobody has run the outcome trial.
The claim
The claim is that vitamin C given into a vein, unlike vitamin C swallowed, reaches concentrations high enough to act against cancer.
What it does
Unusually for this register, the first half of that claim is correct and measurable. By mouth the plasma concentration is held at a ceiling of roughly 100 to 220 micromolar. Into a vein it reaches the millimolar range, around a hundred times higher, because the intravenous route bypasses the absorption and excretion controls entirely.1
At those concentrations ascorbate is proposed to act as a source of hydrogen peroxide around cells rather than as an antioxidant, which is a different mechanism from the one people usually have in mind.1
The evidence
This is the part that is missing. Phase I and II studies of pharmacological ascorbate in advanced cancer have addressed tolerability rather than whether it helps. There is no outcome trial.2
That absence is why the grade is D, and the reason matters. This is not a compound defeated by the concentration argument, the way curcumin is. It clears that hurdle and then nobody built the trial.12
The history also explains an old confusion. The trials that found nothing gave vitamin C by mouth; the series that reported a benefit gave it intravenously as well as orally. Nobody knew that mattered, because the pharmacokinetics were not done until decades later. Twenty years of a settled conclusion rested on a measurement nobody had taken.1
The studies this rests on
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Phase I and II studies of pharmacological ascorbate in advanced cancer2
A trial with no comparison group, open label, phase 1, measured safety.
addressed tolerability rather than efficacy.
What is absent
No trial has tested whether intravenous ascorbate changes a cancer outcome. The human studies that exist measured whether it can be given, not whether it does anything.
Scope: any cancer outcome, intravenous route.
Established by published review, current reviews of pharmacological ascorbate, as recorded in chapter 17 note 11, checked 2026-09-16. Result: the phase I and II studies addressed tolerability rather than efficacy.2
What to ask
Is intravenous vitamin C something with trial evidence behind it, or is it still an open question?
The dish-to-person gap
Given into a vein, ascorbate bypasses the controls that cap the oral route and reaches concentrations in the millimolar range, roughly a hundred times higher than anything achievable by mouth. This is the rare case in the register where a compound does reach the concentration its mechanism requires.1
When to call your team — no warning signs are recorded
Whatever you are taking or thinking of taking, the people treating you can only weigh it if they know about it. That is true when nothing has been written down here, and it is most true then.
The register records no warning signs for intravenous vitamin C. That is not a statement that nothing can go wrong.
Interactions
The register holds no measured interaction between intravenous ascorbate and a cancer treatment class.
Nobody having looked is not the same as nothing being there. That is what this line says and all it says.
The whole interaction list, and how to turn it into a pharmacy review request.
Find a trial instead
This is an entry where the honest answer to "should I try it" is that the outcome trial has not been done, and a trial is where it would be.
Search ClinicalTrials.gov for recruiting studies of ascorbic acid OR ascorbate
A trial is the same decision with monitoring, a known preparation and a doctor who knows what else you are taking.
References
Padayatty SJ, Levine M, and colleagues, 2004, and related pharmacokinetic work.
doi:10.7326/0003-4819-140-7-200404060-00010 · PubMed 15068981
How this was reached: transcribed from chapter note, via docs/CHAPTER-NOTES.json, chapter 17 note 10. The author string is abbreviated in the source that was read and has not been expanded.
Phase I and II studies of pharmacological ascorbate in advanced cancer, cited in current reviews as Hoffer 2008 and 2015 and Stephenson 2013.
No persistent identifier recorded.
How this was reached: transcribed from chapter note, via docs/CHAPTER-NOTES.json, chapter 17 note 11.