How We Use High-Dose Vitamin C
The High-Dose Vitamin C Protocol
Vitamin C is incredible. Since the early days of vitamin C research, this has been obvious. Frederick Klenner, MD, used vitamin C and thiamine in his practice in the mid-1900s. Linus Pauling, PhD, and Ewan Cameron, MD, researched its use in advanced cancer patients in the United Kingdom. Paul Marik, MD and Pierre Kory, MD conducted pioneering research on vitamin C in emergency and intensive care medicine. Doctors all over the world use vitamin C every day in private clinics. Patients rave about the benefits and come back for infusion after infusion.
In my practice, we use vitamin C extensively based on clinical experience and patient feedback.
Fred’s Story: His Experience with Vitamin C
[Individual results. Not typical. Not medical advice. Vitamin C is not intended to treat, cure, or prevent any disease.]
Fred came to see us from Delaware. He had been struggling with back pain, diabetes, and his weight for years. His back pain was so severe that he was planning on having surgery.
Back surgeries often have disappointing outcomes. Many books have been written on the causes of back pain and alternatives to surgery. In my view, many cases can be addressed with mind-body medicine and proper diet and exercise.
Fred was looking for options. I recommended vitamin C to him as part of his initial protocol, not specifically targeting his back pain. To my surprise, he reported a few weeks later that his back pain had improved from an 8 out of 10 to a 2 out of 10.
Important: Fred’s results are individual to him and should not be expected by others. Many factors contributed to his experience, including other dietary and lifestyle changes he made. This is why we often include vitamin C as part of comprehensive protocols in our practice.
The Repair Deficit Connection
Vitamin C is vital to many biological processes. It is also one of the nutrients most depleted by modern diets, lifestyles, and environments. Modern food processing significantly reduces vitamin C content. This means that many people may need more than they typically consume.
Vitamin C is necessary for collagen production, immune function, and the synthesis of various hormones and neurotransmitters. Based on my clinical framework of “repair deficit,” I believe adequate vitamin C intake supports the body’s natural repair processes.
Frederick Klenner, MD, used injectable vitamin C in his practice in the mid-1900s, including with polio patients. He reported positive outcomes, though detailed data on his results is limited. His work remains influential in orthomolecular medicine circles.
In my practice, vitamin C is something I discuss with most patients. I caution you against using vitamin C products without careful vetting. I know the product we use works well in clinical practice because of consistent patient feedback. Our patients and staff have used many brands of vitamin C over the years, and we’ve found significant variation in quality and effectiveness.
Important: Vitamin C supplementation is not medical treatment for autoimmune disease or any other condition. This represents my clinical approach based on the “repair deficit” framework, which is my perspective, not established medical treatment.
Financial Disclosure: I earn a commission on vitamin C and other supplements sold through links in this article. This helps support my writing and research. I only recommend products I personally use and recommend in my clinical practice.
You can purchase Dr. Stillman’s Vitamin C in our online supplement store.
Use this code for 10% off: Klenner
Premium subscribers get 25% off with a monthly discount code (upgrade today and check out your premium subscriber benefits).
Remember: This is the same product I use personally and recommend to patients in my practice, but individual needs vary. Consult your healthcare provider before beginning any new supplement protocol.
Addressing Common Concerns About Vitamin C
Despite vitamin C’s widespread use, there are common concerns people raise:
“It’ll give you kidney stones.”
“Synthetic vitamin C ruins copper metabolism.”
“Only natural vitamin C can be used by the body.”
In my clinical experience using properly formulated, buffered vitamin C products, I have not observed these issues becoming clinically significant problems. However, quality varies tremendously among vitamin C products.
The product we use in our practice is carefully formulated as a properly buffered, fully-reacted form of vitamin C. We vet our vitamin C for potency and purity. Patient feedback consistently indicates good tolerability and benefits.
That said, individual responses vary. Some people may experience adverse effects from vitamin C supplementation, which is why medical supervision is important, especially at high doses.
The High Dose Vitamin C Protocol
Disclaimer: The following represents how I approach vitamin C supplementation in my practice. This is educational information only. Individual needs vary significantly.
Your body has a limited capacity to absorb vitamin C from your gut. At a high enough dose, vitamin C will cause loose stools or diarrhea. This response varies significantly between individuals and can change based on health status.
In my practice, I often suggest starting with a daily dose that keeps stools soft but formed, with at least one bowel movement daily. For those dealing with constipation, vitamin C can be a useful tool.
In all cases, we start by determining tolerance. Most patients can tolerate a few teaspoons of vitamin C daily (some tolerate less). Some patients can tolerate much larger amounts.
Determining Your Need for Vitamin C
Why is there such a wide range of tolerances?
This appears to relate to individual vitamin C needs. In my observation, patients with greater needs (such as during acute illness or stress) can tolerate more. As the body’s immediate needs are met, tolerance often decreases.
Here is the approach I use in practice to determine tolerance:
Plan a quiet day at home
Take a half-teaspoon of vitamin C in four ounces of water when you wake up
Take another half-teaspoon every twenty minutes thereafter
Stop when you have a loose bowel movement
This establishes your “bowel tolerance dose.”
This is important because this is the dose I may suggest patients consider during acute illness, under medical supervision.
When High-Dose Vitamin C May Be Considered
In my practice, I may discuss high-dose vitamin C (up to bowel tolerance) for:
Acute injury
Acute infection
Insect or animal bites or stings
Food poisoning
Other acute stressors
In each of these acute scenarios, the body’s need for vitamin C may be elevated. The body may tolerate more than usual. Patients sometimes report tolerating dozens more grams during acute illness compared to their normal tolerance.
Important: This is not medical treatment for these conditions. Serious injuries, infections, envenomations, and poisonings require immediate medical attention. Vitamin C may be considered as supportive nutrition alongside appropriate medical care.
For general health support, I often suggest daily vitamin C supplementation. There are situations in which we pause vitamin C, but for the most part I suggest patients continue it long-term. It is one of very few supplements I recommend for daily use.
Dosing Approach
Keep track of how much you’ve taken. The quantity that causes a loose stool is your bowel tolerance. This is your maximum dose.
General approach: If you reduce your max dose by 25-30%, that’s often a comfortable daily amount. I typically suggest splitting the dose (morning and night).
Again, it’s critical to use a properly buffered, fully-reacted form of vitamin C. We carefully vet our vitamin C for potency and purity.
Important: High-dose vitamin C should be undertaken with medical supervision. Individual needs vary significantly. Start with lower doses and increase gradually while monitoring response.
Final Thoughts
Vitamin C is one of the supplements I use most frequently in my practice based on clinical experience and patient feedback.
Financial Disclosure: I earn a commission on vitamin C sales through these links. Your purchases fuel our content production - thank you for supporting this work!
You can purchase Dr. Stillman’s Vitamin C in our online supplement store.
Use this code for 10% off: Klenner
Premium subscribers get 25% off with a monthly discount code (upgrade today and check out your premium subscriber benefits).
Important Medical Disclaimer: All information in this article is for educational purposes only and does not constitute medical advice. I am not your doctor. Do not begin high-dose vitamin C without consulting your healthcare provider. Individual results vary significantly.
Until next time, be well,
Dr. Stillman
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Hi, Dr. Stillman... wanted to purchase some Vit C from your online store... SOLD OUT. 😩
Thank you! What I appreciated about this piece is that it is very clear about how you actually think in practice rather than keeping vitamin C in the realm of vague theory. The article is strongest when it connects dosing, bowel tolerance, formulation, and clinical context into a coherent framework, because that gives readers a tangible sense of how you approach this tool rather than simply praising it in the abstract. I also appreciated the transparency around financial disclosure and the repeated reminders that this reflects your clinical perspective rather than established standard treatment, which adds an important layer of honesty to a topic that is often discussed with too much certainty. 
One place where I think the piece could become even stronger is in separating more explicitly what comes from historical orthomolecular experience and patient feedback from what is supported by stronger modern clinical trial evidence. The references to Klenner, Pauling, and more recent physician experience are interesting and certainly part of the history of this conversation, but the article would become even more persuasive if readers were given a sharper evidence hierarchy around claims for acute infection, injury, and other high-stress states. That added calibration would not weaken the argument; it would likely strengthen trust, especially for medically literate readers trying to distinguish physiologic plausibility, clinical observation, and established standard-of-care evidence. 
Overall, I thought this was an engaging and valuable piece because it invites readers to think about vitamin C not as a simplistic wellness cliché, but as a dose-, context-, and formulation-dependent intervention. Even where one may want more careful evidence-grading, the post clearly reflects serious clinical curiosity and a desire to help people think more precisely about how supportive therapies are actually used in real-world practice. Thought-provoking and well worth the read!