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Orthomolecular Medicine News Service, May 9, 2023

Vitamin C for Asthma and Allergies
The high-dose protocol of Robert F. Cathcart III, MD

by Andrew W. Saul, Editor

OMNS (May 9, 2023) One day, my next door neighbor came to my door and said her 5-year-old had scarfed down half a bottle of vitamin C chewables. She wondered, naturally, if there was danger. I asked if the child was showing any symptoms. She thought for a moment, and replied, "Well, his asthma went away." For asthma, Robert Cathcart, MD, recommended a daily vitamin C dosage of between 15,000 to 50,000 milligrams (mg), divided into eight doses. The doctor reported that he had seen this work again and again.

I first saw Dr. Cathcart on the Phil Donahue television show. Dr. Cathcart was seated on stage with five other guests, as Donahue moved about the studio audience soliciting their input that dominated the segment. Near the end of the program, Dr. Cathcart got a direct question about vitamin C. He answered with megadose-specific information for treating disease. The audience erupted with questions, hands up all over. The show was already going to credits before he could answer further.

Impressed, I began to read about this man's work. I found that Cathcart looked at allergy, asthma, and many other conditions simply in terms of how much vitamin C it takes to cure them.

I had a client once who was allergic to everything, literally. She said that she'd tested out positive as allergic to 72 different substances. I'd never heard of that severe a condition before, and apparently, neither had her allergist. He said that she could take a "megadose" of perhaps 1,000 milligrams a day. It was not doing anything. I suggested she take vitamin C to bowel tolerance, and hold the C level just below the amount that caused loose stools. This turned out to be nearly 40,000 milligrams a day.

She took all the C she could hold. When retested, she was allergic to zero substances.

"Vitamin supplements are safe. I have never seen a serious reaction to vitamin supplements. Since 1969 I have taken over 2 tons of ascorbic acid myself. I have put over 20,000 patients on bowel tolerance doses of ascorbic acid without any serious problems, and with great benefit."

(Robert F. Cathcart, M.D.,

Here is a personal communication I received from Dr. Cathcart in June, 2006 on the subject of vitamin C, allergy, and drug reactions:

I believe that acute and chronic deficiency of vitamin C is necessary for anaphylactoid allergic reactions.

When I first moved to Incline Village, NV, in 1970, they were in the midst of a beta hemolytic strep epidemic. I gave at least 300 patients penicillin, ascorbic acid (to tolerance), and acidophilus. Not a single patient had an allergic reaction to the penicillin. It is my understanding that approximately 3% of patients who have not had reactions before will have them on subsequent exposures. One day a man, who had received the penicillin elsewhere without the vitamin C, came in with the typical urticarial skin rash all over. I seized the opportunity and gave him an intravenous injection of 20 grams of sodium ascorbate. In 15 minutes, the rash cleared. I instructed him to take bowel tolerance doses of ascorbic acid and like a good physician, I prescribed him some Benadryl. The next day he returned and asked me why I had wasted his money on the Benadryl because the rash had never come back.

I have treated many cases of hay fever and asthma. I have gotten many patients with asthma off steroids. I have never failed to have a patient with these allergic reactions to not markedly reduce or eliminate the need for other medications when they took bowel tolerance doses of ascorbic acid properly. One of the things that got me into massive doses of ascorbic acid was that it eliminated my having to take any antihistamines for my hay fever.

It is interesting that I understand that when a patient with mononucleosis is accidentally given penicillin that almost one half will have an allergic reaction to the penicillin. With ampicillin almost all will have a reaction. I find this interesting because mononucleosis is one of the world champs at increasing bowel tolerance to ascorbic acid. Young adults regularly find their bowel tolerance somewhere around 200 grams of ascorbic acid per day for a couple of days with acute mononucleosis.

It is my impression due to experience over the years that ascorbic acid orally and sodium ascorbate intravenously reduces the reactions to all sorts of medications. This has been particularly noticed in patients taking chemotherapy for cancer.

Bob Cathcart

In 2000, Dr. Cathcart told me that I should forget the medical journals and the commercial media, and focus on the internet for publishing, because it was a direct way to reach a lot of open-minded, interested people. He was always very gracious to me, and his work taught me a lot. In lectures, I would wryly instruct my university students to definitely avoid reading his papers, because if they did, it would change their lives forever.

As it did mine.

(Andrew W. Saul has served as Editor-in-Chief of the Orthomolecular Medicine News Service for nearly 20 years. He is the author or coauthor of twelve books and editor of 13 more. The author is not a physician and is obviously not a confidant of very many allergists. Work directly with your doctor before making any medication or other treatment changes.)

For further reading:

Swenson R. Dr. Robert Fulton Cathcart III: Pioneer in Orthomolecular Medicine. Orthomolecular Medicine News Service, Apr 17, 2020

Cathcart RF. Vitamin C, titrating to bowel tolerance, anascorbemia, and acute induced scurvy.

Cathcart RF. The Method of Determining Proper Doses of Vitamin C for the Treatment of Disease by Titrating to Bowel Tolerance. J Orthomol Psychiat, 10:125-132.

Dr. Robert Cathcart, vitamin C pioneer. Online video:

Vitamin C Library:

Vitamin C, Titrating to Bowel Tolerance, Anascorbemia, and Acute Induced Scurvy.

Stone I (1972) The Healing Factor: Vitamin C Against Disease. Grosset and Dunlap, New York. ISBN-13: 9780448116938. or

Dr. Cathcart was inducted into the Orthomolecular Medicine Hall of fame in 2008.

That same year, Wikipedia summarily deleted his biography page. .

Scroll down at for additional reporting on this.

To learn still more about Dr. Cathcart:

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Andrew W. Saul, Ph.D. (USA), Editor-In-Chief
Associate Editor: Robert G. Smith, Ph.D. (USA)
Editor, Japanese Edition: Atsuo Yanagisawa, M.D., Ph.D. (Japan)
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