What Type of Vitamin C Is Used in IV?

January 3, 2026 •

3 min read

Intravenous (IV) vitamin C is delivered directly into the bloodstream, achieving concentrations up to 70 times higher than oral supplements. This process requires a specific, carefully prepared form of vitamin C to ensure safety and effectiveness, bypassing the digestive system's limitations.

Quick Summary

IV therapy uses a buffered form of vitamin C, typically sodium ascorbate, created by adjusting pure ascorbic acid to a neutral pH for safe intravenous infusion. This bypasses gastrointestinal issues and allows for significantly higher plasma concentrations.

Key Points

Specific Form: The vitamin C used for intravenous infusion is the buffered form known as sodium ascorbate, not pure ascorbic acid.
Why it's Buffered: Buffering is necessary to neutralize the natural acidity of ascorbic acid, preventing irritation to blood vessels and making high-dose infusions safe for the body.
Higher Concentration: IV administration allows for significantly higher vitamin C plasma concentrations than oral intake, which is critical for its therapeutic effects.
Preparation is Key: Concentrated vials of ascorbic acid injection (which becomes sodium ascorbate) are diluted with a carrier fluid like saline before infusion under sterile conditions.
Medical Screening is Crucial: High-dose IV vitamin C is not for everyone; screening is necessary to identify risks for individuals with G6PD deficiency, kidney issues, or hemochromatosis.
Diverse Applications: Beyond treating scurvy, IV vitamin C is explored for immune support, its pro-oxidant effects against some cancer cells, and overall wellness.
Not FDA Approved for Cancer: Despite research, the FDA has not approved high-dose IV vitamin C as a treatment for cancer, and it is considered a complementary therapy.

The Primary Form: Sodium Ascorbate

When vitamin C is administered intravenously, it's typically in the form of sodium ascorbate, not pure ascorbic acid. Ascorbic acid is naturally acidic, which can irritate blood vessels and cause discomfort when infused directly, especially at the high concentrations used in IV therapy. To make it suitable for IV use, buffering agents like sodium bicarbonate or sodium hydroxide are added to ascorbic acid to neutralize its acidity. This process creates sodium ascorbate, the sodium salt of ascorbic acid, which is significantly safer and better tolerated for intravenous administration. Although the product might be labeled “Ascorbic Acid Injection,” it is formulated to yield sodium ascorbate when prepared for IV use.

The Preparation Process

Concentrated injectable vitamin C solutions require dilution before intravenous administration. A healthcare provider or pharmacist prepares the solution by adding the concentrated vitamin C to a compatible carrier fluid, such as normal saline or 5% dextrose in water, using aseptic techniques. This dilution ensures the infusion is safe and isotonic, matching the concentration of the body's fluids. This meticulous preparation is vital for safely achieving the high vitamin C levels in the bloodstream that oral intake cannot provide.

Ascorbic Acid vs. Sodium Ascorbate for IV Use

The distinction between ascorbic acid and sodium ascorbate is crucial for intravenous administration due to their differing properties.


Feature	Ascorbic Acid (Pure)	Sodium Ascorbate (Buffered)
Acidity (pH)	Highly acidic, unsuitable for direct IV infusion.	Neutral pH (5.6-7.0), making it safe for intravenous use.
Form	The natural form of vitamin C.	A mineral salt of ascorbic acid created by buffering.
Tolerability	Can cause vessel irritation and gastrointestinal distress.	Significantly better tolerated by blood vessels and the body.
Delivery Method	Not for IV use in its pure, unbuffered state.	The standard and only medically accepted form for intravenous use.
Effect in Body	Acts as an antioxidant, but high oral doses have limited absorption.	Achieves very high plasma concentrations, potentially acting as a pro-oxidant in high doses.
Application	Used in oral supplements and certain food products.	Used for all high-dose intravenous vitamin C therapies.

Benefits of High-Dose IV Vitamin C

High-dose intravenous vitamin C is utilized for applications where very high plasma concentrations are desired, levels unattainable through oral supplements. It is a medical treatment for severe vitamin C deficiency (scurvy) when oral administration is not feasible. Additionally, IVC is used in integrative medicine for potential benefits in immune support, anti-aging, and as an adjunctive therapy in cancer care.

Immune System Support: High doses can enhance immune function by supporting white blood cell activity.
Antioxidant/Pro-oxidant Balance: While an antioxidant at normal levels, high IV concentrations may act as a pro-oxidant, potentially affecting certain cancer cells.
Improved Quality of Life: Some studies suggest high-dose IVC may improve the quality of life and reduce side effects for cancer patients.
Collagen Synthesis: Essential for collagen production, IV therapy may aid tissue repair and wound healing.

Safety Considerations for IV Vitamin C

Despite being generally well-tolerated, high-dose intravenous vitamin C requires medical oversight and is not suitable for everyone. Patients must be screened for specific health conditions that could increase risks.

G6PD Deficiency: Individuals with this genetic disorder risk red blood cell breakdown (hemolysis) with high-dose vitamin C. Screening is mandatory.
Kidney Issues: A history of kidney disease or stones increases the risk of kidney problems due to how the body metabolizes vitamin C into oxalate.
Hemochromatosis: High vitamin C doses can dangerously increase iron absorption in patients with this iron overload condition.
Fluid Overload: The volume of IV fluid can be problematic for individuals with heart or kidney conditions.

Conclusion

Intravenous vitamin C uses a buffered, pH-neutral solution of sodium ascorbate, prepared from ascorbic acid. This specific form is vital for safety, preventing the vascular irritation that pure, acidic ascorbic acid would cause, particularly at high IV doses. While used for various purposes like immune support and complementary cancer therapy, IV vitamin C requires medical supervision and is not suitable for individuals with certain health conditions. Consulting a qualified healthcare professional is essential to determine if this therapy is appropriate and safe.

For more information on the research and clinical aspects of intravenous vitamin C, consult reliable sources such as the National Cancer Institute's PDQ summary: Intravenous Vitamin C (PDQ®) - NCI.

Frequently Asked Questions

Pure ascorbic acid is highly acidic and would cause significant irritation and damage to blood vessels if infused directly. The pH must be neutralized by buffering to prevent patient discomfort and physiological disruption.

The main difference is the achievable concentration in the blood. Oral intake is limited by intestinal absorption, while IV infusion bypasses this control, allowing for much higher plasma concentrations of vitamin C.

To create the pH-neutral sodium ascorbate, manufacturers of intravenous solutions add buffering agents such as sodium bicarbonate or sodium hydroxide to the ascorbic acid.

High-dose IV vitamin C should be avoided by individuals with certain pre-existing conditions, including G6PD deficiency, a history of kidney disease or kidney stones, and hemochromatosis (iron overload).

Research into IV vitamin C as a complementary cancer therapy is ongoing, with some studies suggesting potential benefits like improved quality of life and reduced treatment side effects. However, the U.S. FDA has not approved it as a cancer treatment, and results have been mixed.

The concentrated vial of ascorbic acid injection is diluted in a suitable carrier fluid, such as sterile water or saline, and prepared under strict aseptic conditions to ensure sterility and proper concentration before infusion.

Side effects are generally mild and may include pain or swelling at the injection site, dizziness, or temporary flushing. More serious risks are primarily linked to pre-existing health conditions that require medical screening.