What is IV vitamin C therapy, and what does the evidence show?

Overview

Scurvy is the disease caused by severe vitamin C deficiency.[1]

A 2026 review identified 280 published cases of scurvy in adults reported from 2000 to 2025, and many of the patients had restrictive diets, were homeless or were socially isolated.[2]

How IV vitamin C differs from vitamin C taken by mouth

In a study of 17 healthy volunteers, a 1.25 gram dose of vitamin C produced an average peak blood level of 134.8 micromoles per liter when taken by mouth and 885 micromoles per liter when given into a vein.[3] The same researchers used a computer model to predict peak blood levels of 220 micromoles per liter for the largest tolerated oral dose, 3 grams every 4 hours, and 13,400 micromoles per liter for a 50 gram IV dose, and noted that patient data were not available to confirm the model at high doses.[3]

In a 1996 study of 7 healthy volunteers who stayed in hospital for 4 to 6 months, blood levels of vitamin C stopped rising at a dose of 1,000 mg a day, and the share of each dose absorbed fell at single doses of 500 mg and above.[4] A higher blood level of vitamin C is a laboratory measurement, and a comparison of an infusion with the same dose by mouth on a health outcome in healthy people is missing from the studies we reviewed, so the higher level from an infusion has not been shown, in healthy people, to lead to better health.

Evidence by use

Evidence levels in this table follow our grading key, which defines Emerging as "Some human controlled evidence exists" that is "small, short, single", "open-label, exploratory, inconsistent or mixed (some primary outcomes positive, some null), resting on surrogate outcomes, or coming mostly or entirely from studies funded by, or with authors employed by, the maker." The key defines Experimental as "No controlled human evidence for the claim as stated. Support is only mechanism, animal, in-vitro, case reports or case series, biomarker or PK data offered for a benefit claim, or observational data offered for a causal benefit claim." It defines Evidence against as "Controlled human trials tested the claim on its primary outcome and did not find the effect, and no controlled trial found it."

In the rows marked No support found in healthy people, our searches of PubMed, Europe PMC and ClinicalTrials.gov on October 1, 2026 found no randomized trial of IV vitamin C in healthy people for that use. For the detox row, that means none that we could confirm was randomized, and for the aging row, the use searched for was slowing aging, lifespan or biological age. Trials in patients are not counted in those rows, and a search result does not show that no such trial exists.

Tiredness and energy

In a randomized, double-blind trial in Korea, 147 healthy office workers aged 20 to 49 were assigned to a single IV infusion of 10 grams of vitamin C or of saline, 141 were analyzed, and scores for current fatigue two hours and one day later were lower in the vitamin C group.[5] The trial also asked about usual fatigue and worst fatigue over the previous 24 hours, and neither differed between the vitamin C and saline groups one day after the infusion.[5]

The office-worker trial gave one dose and measured fatigue for one day, so it says nothing about repeated infusions or lasting effects. The office-worker trial was supported by the Korean Association for Vitamin Research, which the paper says had no role in the study, and one author chaired that association while another was a member.[5] In the office-worker trial, IV vitamin C lowered a blood marker of oxidative stress compared with saline, and a change in a blood marker does not show a health benefit.[5]

A 2021 review of IV vitamin C for fatigue resulting from various diseases identified 9 clinical studies with 720 participants and reported that three of the four controlled trials found lower fatigue scores with vitamin C, and one of the review's two authors was employed part time by Pascoe, a company that markets an ascorbic acid injection.[6][7]

Ascor and generic ascorbic acid injection are FDA-approved only for short-term treatment of scurvy, not for energy or fatigue. Using ascorbic acid injection for energy or fatigue is off-label. FDA has not reviewed whether it is safe and effective for that purpose.

Colds and immune function

A search of PubMed, Europe PMC and ClinicalTrials.gov on October 1, 2026 found no randomized trial of IV vitamin C in healthy people for immune function, colds or flu. A 2025 before-and-after study of healthy adults gave IV vitamin C at 7.5 grams a day for three days and reported higher CD4+ and CD8+ T lymphocyte and eosinophil counts afterward, with the results within accepted biological variability ranges, and a 1981 study of six volunteers given 1 gram by IV reported higher neutrophil motility and lymphocyte transformation an hour later.[8][9] Neither study described a control group or measured colds, flu or infections, and we read only their abstracts.[8][9] Our searches of PubMed, Europe PMC and ClinicalTrials.gov on October 1, 2026 returned other studies of this kind in healthy volunteers, and the abstracts we read for them also describe no control group or random assignment.

A 2013 Cochrane review pooled 29 trial comparisons with 11,306 participants, and in its general-community trials, with 10,708 participants, taking vitamin C regularly did not lower the number of people who caught a cold (risk ratio 0.97, 95% confidence interval 0.94 to 1.00).[10] In the same Cochrane review, regular vitamin C shortened colds in adults by 8% (95% confidence interval 3% to 12%), and trials that used vitamin C to treat a cold showed no consistent effect on how long colds lasted or how severe they were.[10] The Cochrane review's summary reports no results for IV vitamin C, so its findings are not evidence about infusions.

Ascor and generic ascorbic acid injection are FDA-approved only for short-term treatment of scurvy, not for immune support or preventing infections. Using ascorbic acid injection for immune support is off-label. FDA has not reviewed whether it is safe and effective for that purpose.

Uses with no randomized trial in healthy people that we found

Our searches of PubMed, Europe PMC and ClinicalTrials.gov on October 1, 2026 found no randomized trial of IV vitamin C in healthy people for skin, slowing aging, lifespan or biological age, and none for detox that we could confirm was randomized.

A 1994 study of 28 adult volunteers, chosen for the highest urinary mercury among 89 screened, gave IV lactated Ringer's solution with and without up to 60 grams of ascorbic acid and reported that mercury excretion in the 24 hours after the vitamin C infusion (average 4.0 micrograms) was not significantly higher than after Ringer's solution alone (3.7 micrograms), and that lead excretion was similarly unaffected.[11] We read only the abstract, which does not say whether the order of the two infusions was randomized or whether the volunteers were healthy, and the full text was not available to us.[11]

The searches also returned acute IV vitamin C infusion experiments in healthy young and older adults, among them reports of no change in exercise capacity (Bell 2005), resting metabolic rate (Bell 2003) and arterial compliance (Eskurza 2004) and of higher baroreflex sensitivity in older men (Monahan 2004), and a registered randomized infusion trial in healthy adults aged 18 to 79 that lists Aging as its condition (NCT03775382) and has no results posted as of October 1, 2026, but the outcomes we read were exercise, metabolic and blood-vessel readings, not slowing aging, lifespan or biological age, and we read only the abstracts and the registry record.[12][13][14][15][16]

The Ascor and generic ascorbic acid injection labels cover short-term treatment of scurvy, not immune support, energy, skin health, cancer, sepsis or longevity (as of September 30, 2026).

Sepsis and critical illness

In the CITRIS-ALI and LOVIT intensive-care trials of sepsis, IV vitamin C did not improve the trials' main outcomes, and LOVIT, a trial of 872 people, found more death or lasting organ dysfunction with vitamin C than with placebo.[17][18]

In the LOVIT trial, 872 adults in intensive care with an infection who needed medicine to support their blood pressure were randomized to IV vitamin C or placebo, and death or persistent organ dysfunction at 28 days occurred in 191 of 429 people given vitamin C (44.5%) and 167 of 434 given placebo (38.5%).[18] The difference in the LOVIT trial was statistically significant, with a risk ratio of 1.21 (95% confidence interval 1.04 to 1.40).[18]

In the CITRIS-ALI trial of 167 adults with sepsis and severe lung failure, a 96-hour IV vitamin C infusion did not significantly improve organ failure scores or markers of inflammation compared with placebo.[17] In the VICTAS trial of 501 adults with sepsis, IV vitamin C combined with thiamine and hydrocortisone did not change ventilator- and vasopressor-free days (a median of 25 days compared with 26 with placebo), and the trial ended early and may have been too small to detect a difference.[19]

A 2023 international guideline panel of 21 experts from 16 countries suggests against using IV vitamin C in adults with sepsis beyond standard nutritional supplementation, as a conditional recommendation.[20] CITRIS-ALI also recorded 28-day mortality of 29.8% with vitamin C and 46.3% with placebo, a result its authors called exploratory because it was one of 46 secondary outcomes analyzed without adjusting for multiple comparisons.[17] A 2026 pooled analysis of 14 randomized trials with 1,958 patients found lower 28-day mortality with IV vitamin C (risk ratio 0.70, 95% confidence interval 0.53 to 0.93), rated that evidence low quality, and reported that the benefit came from single-center studies and was not seen in multicenter trials.[21]

In the 2026 VICTORY trial of 238 adults with severe burns, which was stopped early for futility or harm, 28-day mortality was 15.0% with IV vitamin C and 7.6% with placebo, while the trial's main combined outcome did not differ significantly between the groups.[22] The sepsis and burns trials studied critically ill adults in hospital, and they are not evidence about IV vitamin C given to healthy people at a clinic.

Ascor and generic ascorbic acid injection are FDA-approved only for short-term treatment of scurvy, not for sepsis or other critical illness. Using ascorbic acid injection for sepsis or other critical illness is off-label. FDA has not reviewed whether it is safe and effective for that purpose.

Cancer research

Lab studies show that high levels of vitamin C can kill some cancer cells, but results in people have been mixed: a small trial in advanced pancreatic cancer found longer survival, and trials in prostate and colorectal cancer found no benefit on their main outcomes.[23][24][25][26]

The Ascor and generic ascorbic acid injection labels cover short-term treatment of scurvy, not immune support, energy, skin health, cancer, sepsis or longevity (as of September 30, 2026).

Our PubMed, Europe PMC and ClinicalTrials.gov searches on October 1, 2026 found no published randomized trial that tested IV vitamin C by itself as a cancer treatment. A 1976 report by Cameron and Pauling compared 100 people with terminal cancer who were given vitamin C with 1,000 similar patients who were not.[27] A 1978 report compared 100 people with terminal cancer who were given vitamin C, usually 10 grams a day, with 1,000 matched controls and put average survival about 300 days longer in the vitamin C group.[28] The 1978 report was a reevaluation, and its paper says its 100 treated patients were mostly the same as those in the 1976 report and that its new set of 1,000 controls overlaps largely with the first set.[28] The 1976 paper says its 1,000 controls came from what it calls a random search of the hospital's case record index of similar patients treated by the same clinicians over the previous 10 years.[27][28] The 1976 report says its 100 treated patients usually received vitamin C at 10 grams a day, by IV infusion for about 10 days and then by mouth.[27] The 1976 paper says it was supported by research grants from the Secretary of State for Scotland and The Educational Foundation of America and by contributions by private donors to the Linus Pauling Institute, and the 1978 paper adds The Foundation for Nutritional Advancement to its grant sources.[27][28] Linus Pauling, the second author of both papers, gave the Linus Pauling Institute of Science and Medicine in Menlo Park, California, as his affiliation, and Ewan Cameron gave the Vale of Leven District General Hospital in Scotland.[27][28] Those reports compared treated patients with matched controls and were not randomized trials, the 1976 report gave vitamin C by IV and then by mouth, and the 1978 paper does not state the route in the text we read, so they do not show what IV vitamin C does by itself.[27][28]

Two double-blind trials published in 1979 and 1985 gave people with advanced cancer 10 grams of vitamin C a day by mouth or a placebo, and neither found longer survival with vitamin C, but neither trial gave vitamin C by IV.[29][30][31]

ClinicalTrials.gov lists a randomized, double-blind trial planned to compare IV vitamin C with saline for quality of life in 40 people with terminal colon cancer (NCT03224572), with a record last updated in January 2018, a status listed as unknown and no results posted.[32] ClinicalTrials.gov also lists a randomized add-on trial of IV vitamin C at 1 gram per kilogram twice weekly for 6 months, compared with saline, planned for 90 people with advanced non-small-cell lung cancer who will all receive platinum doublet chemotherapy (NCT05849129), with a recruiting status in a record last updated in January 2026 and no results posted.[33]

A 2014 systematic review of IV vitamin C in cancer found 2 randomized trials, 15 uncontrolled trials, 6 observational studies and 14 case reports, and concluded that the existing evidence is preliminary and cannot be considered conclusive.[34] In a 2005 laboratory study of 10 cancer and 4 normal cell types, high concentrations of vitamin C killed several cancer cell lines and did not affect normal cells, and a laboratory result does not show that a treatment works in people.[23]

In a 2024 trial, 36 people with stage IV pancreatic cancer were randomized and 34 were treated, and adding 75 grams of IV vitamin C three times a week to gemcitabine and nab-paclitaxel chemotherapy was followed by overall survival of 16 months, compared with 8.3 months with the chemotherapy alone.[24] The pancreatic cancer trial treated 34 people and reported its result with a 90% confidence interval (hazard ratio 0.46, 0.23 to 0.92), and in searches of PubMed, Europe PMC and ClinicalTrials.gov on October 1, 2026 we found no other published randomized trial of IV vitamin C in pancreatic cancer.[24]

ClinicalTrials.gov lists another completed randomized trial in advanced pancreatic cancer (NCT01905150, 34 people enrolled), whose posted results describe two groups that both received IV vitamin C with chemotherapy, one of them after a delay, and neither the record nor our PubMed and Europe PMC searches on October 1, 2026 turned up a journal article reporting it.[35]

In a 2024 double-blind trial, 50 men with metastatic castration-resistant prostate cancer were randomized and 47 were treated, and adding IV vitamin C to docetaxel chemotherapy did not improve the PSA response rate among those treated (41% of the 32 men given vitamin C and 33% of the 15 given placebo), and the trial was suspended after an interim analysis indicated futility.[25] In the prostate cancer trial, median overall survival was 15.2 months in the vitamin C group and 29.5 months in the placebo group, a difference that was not statistically significant (hazard ratio 1.98, 95% confidence interval 0.85 to 4.58).[25]

In a 2022 open-label phase 3 trial of 442 people with metastatic colorectal cancer, adding IV vitamin C to FOLFOX chemotherapy with or without bevacizumab did not lengthen progression-free survival (a median of 8.6 months compared with 8.3 months) or overall survival (a median of 20.7 months compared with 19.7 months).[26] In the colorectal cancer trial, a subgroup analysis that the paper says was planned in advance found longer progression-free survival with added vitamin C among the 203 people whose tumors had a RAS mutation (a median of 9.2 months compared with 7.8 months; hazard ratio 0.67, 95% confidence interval 0.50 to 0.91), and overall survival in that subgroup did not differ significantly (20.2 months compared with 16.8 months).[26] That finding comes from one subgroup of one open-label trial whose main result showed no benefit, and its authors said it justifies larger trials in people with RAS-mutant colorectal cancer, so it is a question for further research and, on its own, is not a reason to seek IV vitamin C.[26] The colorectal cancer trial's paper says it was supported by grants from the Sun Yat-sen University Clinical Research 5010 Program, the National Natural Science Foundation of China, the Science and Technology Program of Guangdong, the Science and Technology Program of Guangzhou and the Program of Guangdong Provincial Clinical Research Center for Digestive Diseases, and that its authors reported no disclosures.[26]

The 2024 pancreatic cancer trial, the 2024 prostate cancer trial and the 2022 colorectal cancer trial described here added IV vitamin C to chemotherapy, and none of the three tested it in place of chemotherapy. The National Cancer Institute's patient summary says that when IV vitamin C is combined with certain anticancer drugs, the anticancer drugs may not work as well, and that so far these effects have been seen only in some laboratory and animal studies.[36] Anyone having cancer treatment who is considering IV vitamin C should talk with their cancer care team first.

Limitations

Our PubMed, Europe PMC and ClinicalTrials.gov searches on October 1, 2026 found no randomized trial in healthy people that assigned people to IV or to oral vitamin C and compared the two routes on a health outcome. In a 2005 open-label trial, 21 people on hemodialysis with iron overload were randomized to 250 mg of vitamin C three times a week by IV or by mouth for 8 weeks, and hemoglobin did not change with either route.[37]

For immunity, colds, skin, slowing aging, lifespan and biological age, our searches of PubMed, Europe PMC and ClinicalTrials.gov on October 1, 2026 found no randomized trial of IV vitamin C in healthy people, and for detox they found none that we could confirm was randomized. These searches looked for trials in healthy people and were not designed to find trials in people who were already ill.

What are the side effects and risks of IV vitamin C?

Reported risks of IV vitamin C include kidney damage from oxalate, kidney stones, breakdown of red blood cells in people with G6PD deficiency, and wrong readings on some blood sugar tests.[1][36]

The Ascor label warns that acute and chronic kidney damage from oxalate has been reported with prolonged use of high doses of ascorbic acid.[1] People with kidney disease, people with a history of oxalate kidney stones, older adults and children under 2 may be at higher risk of that kidney damage, according to the Ascor label.[1] Ascorbic acid also makes urine more acidic, which the Ascor label says may lead to cysteine, urate or oxalate stones.[1]

A 1985 case report describes a patient with primary amyloidosis and nephrotic syndrome who developed acute kidney failure after a single 45 gram IV dose of ascorbic acid, and an examination after death found calcium oxalate deposits in the kidney tubules.[38]

Hemolysis, the breakdown of red blood cells, has been reported in people with G6PD deficiency given ascorbic acid, and the Ascor label warns that people with this inherited condition may be at higher risk of severe hemolysis.[1][36] A 2022 review found 14 published case reports of hemolysis after vitamin C at doses of 1 to 200 grams a day, 57.1% of them after IV use, and about 71.4% of the patients had G6PD deficiency and one death was reported.[39]

Pain and swelling at the infusion site are among the adverse reactions on the Ascor label, which also says infusing faster than 250 mg a minute may cause temporary faintness, nausea, lethargy, flushing, dizziness and headache.[1] On drug interactions, the Ascor label says ascorbic acid may lower the activity of the antibiotics erythromycin, kanamycin, streptomycin, doxycycline and lincomycin, and that limited case reports suggest it may interfere with the blood thinner warfarin, although no effect was seen at up to 1,000 mg a day for 2 weeks.[1]

A 2020 scoping review of 74 studies, in which 2,801 people received high-dose IV vitamin C, found no consistent evidence that it was more harmful than placebo in double-blind randomized trials, and counted five cases of oxalate kidney damage, five of high blood sodium, three of hemolysis in people with G6PD deficiency and two of glucose meter error.[40] That scoping review was published in 2020, before the LOVIT sepsis trial and the VICTORY burns trial reported worse results with IV vitamin C in critically ill adults.

LOVIT, a trial that randomized 872 intensive-care patients, recorded death or persistent organ dysfunction at 28 days in 191 of 429 given IV vitamin C (44.5%) and 167 of 434 given placebo (38.5%), a statistically significant difference.[18] In the LOVIT trial, one patient in the vitamin C group had a severe episode of low blood sugar and another had a serious anaphylactic reaction.[18] In the VICTORY burns trial of 238 adults, which was stopped early, 28-day mortality was 15.0% with IV vitamin C and 7.6% with placebo, although the trial's main combined outcome did not differ significantly.[22] Both trials enrolled critically ill adults in hospital, so their results do not show what happens when healthy people have IV vitamin C at a clinic.

High-dose IV vitamin C can make some blood sugar tests read wrong, too high or too low depending on the device and test method, for up to a day after an infusion.[1][41] The Ascor label says ascorbic acid may interfere with laboratory tests based on oxidation-reduction reactions, including blood and urine glucose tests, and that such tests should be delayed until 24 hours after an infusion if possible.[1] In a 2022 study of one hospital glucose meter, the Accu-Chek Inform II, blood samples with vitamin C added read 1.4 mmol/L higher for every 1 mmol/L of vitamin C, and vitamin C levels below 0.8 mmol/L did not interfere.[41] In the same study, 83% of the meter's readings in 41 blood samples from 16 critically ill patients given IV vitamin C at 25 mg per kilogram every 6 hours met the ISO 15197:2013 accuracy standard, and the authors concluded that this dose does not interfere with the meter unless the patient has kidney impairment, in which case laboratory glucose tests should be used.[41] People who check their blood sugar should tell the clinician giving the infusion and ask how to test in the day after it.[1]

Anyone with a medical condition, or taking other medicines, should ask a licensed clinician before having IV vitamin C.

Sources: Ascor injection prescribing information, Revised 7/2022.

Who should not get high-dose IV vitamin C?

The groups that the sources we reviewed name for caution with high-dose IV vitamin C include people with kidney disease, people prone to kidney stones, people with G6PD deficiency and people with hemochromatosis.[1][36]

The National Cancer Institute's patient summary says kidney failure has been reported after IV vitamin C in people with a history of kidney disease.[36] According to the same summary, people who are likely to develop kidney stones should not be treated with IV vitamin C.[36] People with G6PD deficiency, an inherited disorder, should not be given high doses of vitamin C because it may cause hemolysis, the summary says, citing case reports.[36] The summary also says high doses of vitamin C are not recommended for people with hemochromatosis, because vitamin C may make iron more easily absorbed and used by the body.[36]

Women who are pregnant or breastfeeding, and people with G6PD deficiency, should not exceed the recommended dietary allowance or adequate intake of vitamin C for their age group and condition, according to the Ascor label.[1]

Sources: Ascor injection prescribing information, Revised 7/2022.

If you have severe symptoms, call 911 or seek emergency care. Report side effects to FDA MedWatch.

Administration methods

In the sepsis, burns, cancer and fatigue trials we reviewed, fixed doses ranged from 1.5 grams to 75 grams per infusion, and weight-based doses ranged from 50 mg per kilogram every 6 hours to 1.5 grams per kilogram a day.[5][17][18][19][22][24][25][26] The Ascor label gives 200 mg as the largest recommended single dose.[1]

The Ascor prescribing information recommends daily treatment for no more than seven days, says to treat again until scurvy symptoms resolve if they have not improved after one week, and does not recommend repeat dosing in children under 11.

The label dose on this page is taken from the Ascor prescribing information, and the study doses are the ones the trials we reviewed used. Neither is an instruction to follow, and a prescriber sets the dose.

Sources: prescribing information, Dosage and Administration section, for Ascor injection prescribing information, Revised 7/2022.

Is IV vitamin C FDA-approved?

Ascorbic acid injection, given into a vein, is an FDA-approved prescription product for short-term treatment of scurvy when oral vitamin C is not possible, insufficient or contraindicated, according to the Ascor and generic labels (as of September 30, 2026).

The FDA status table lists the ascorbic acid injection products whose prescribing information we reviewed, with how each is given and the use on its label.

Each ascorbic acid injection product in the FDA status table is available only with a prescription (as of September 30, 2026).

Completing an intake form or making a payment does not guarantee a prescription.

Ascor and generic ascorbic acid injection are FDA-approved only for short-term treatment of scurvy. The Ascor label states: 'ASCOR is not indicated for treatment of vitamin C deficiency that is not associated with signs and symptoms of scurvy.' Using ascorbic acid injection for vitamin C deficiency without signs of scurvy is off-label.

Compounded ascorbic acid injection is a different product from the ascorbic acid injection products in the FDA status table. We do not know which one a given provider uses.

Compounded ascorbic acid injection is not FDA-approved. FDA states: 'Compounded drugs are not FDA-approved. This means that FDA does not verify the safety, effectiveness or quality of compounded drugs before they are marketed.' As of FDA's list updated March 21, 2025, ascorbic acid and sodium ascorbate are on FDA's list of substances under evaluation for use by outsourcing facilities (503B Category 1), and this listing is not an FDA approval of any compounded product.

Regulatory status checked September 30, 2026. Sources: dailymed.nlm.nih.gov/…/lookup.cfm; dailymed.nlm.nih.gov/…/lookup.cfm; www.fda.gov/…/download; www.fda.gov/…/download; www.fda.gov/…/compounding-and-fda-questions-and-answers; www.fda.gov/…/fda-notification-regarding-ascorbic-acid-injection

Questions to ask a provider

• Have I been checked for G6PD deficiency?
• Do my kidney function or a history of kidney stones change whether this infusion is appropriate for me?
• What dose will I receive, and how fast will it be infused?
• How should I check my blood sugar in the day after the infusion?
• Could this infusion interact with my cancer treatment or my other medicines?
• Which vitamin C product do you use, and who makes it?

Provider directory

Compounded ascorbic acid injection is not FDA-approved. See FDA's statement.

You can connect with a licensed provider to ask about an evaluation.

Find a Provider · Connect With a Licensed Provider

A licensed clinician decides whether treatment is appropriate. A prescription is not guaranteed.