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High dosage vitamin C for cold and flu

The below are my documented notes on high dosage vitamin C treatment for cold and flu. This should go without saying that this is not advice for other people but documentation of my own experience and my family's own experience so far. We are doing what we can to experiment with this in a cautious way.

The Concept

The overall concept is that your body will absorb vitamin C based on its current needs. When battling a cold or flu, the body will absorb substantially more than when healthy.

The point of absorption tolerance is identified by the point when diarrhea occurs. I have personally found this point to fluctuate dramatically when under the weather.

There are side effects and possible risks of vitamin C overdose through supplementation that I have been closely monitoring. I am remaining cautious in not engaging in this for extended periods of time. However, there is additional research that appears to show that the concerns of vitamin C causing kidney stones may be unwarranted.

Reference: X post from Dr. Syed Haider


Last updated December 7, 2023

  • Started experimenting with this September 28, 2023.
  • As of over two months into this, I have noticed a dramatic difference personally.
  • Prior to starting this, waking in the morning after a night of short sleep (less than 7 hours), would leave me feeling run down. This would happen almost every time I would awake from a shorter sleep. Now, if I go to bed late and know I will be getting a shorter sleep, I take 3,000mg before bed. I have not felt run down when waking up on short sleep since doing this.
  • Any time I have started feeling under the weather during the day, I start with 3,000mg and continue with 2,000mg every hour or couple of hours until I begin feeling better or until diarrhea hits. Most of the time, I feel better and diarrhea never hits. The results have been surprisingly quick.
  • The overall feel so far is that I've stumbled upon a health hack, but remain cautious about side effects.
  • Children
    • While we have been more conservative with the amounts given to kids, we have noticed considerable improvement in their ability to rebound from colds quickly. We have not seen colds linger for more than two days for the older kids.
    • Severity of colds seems to have decreased as well


My preferred method:

  • Start with 3,000-4,000mg depending on extent of cold/flu symptoms
  • Take additional 2,000 mg every couple hours until feeling better or diarrhea hits

My preferred method for kids:

  • Start with 1,000-2,000mg depending on extent of cold/flu symptoms
  • Followed by 1,000mg every couple hours, and not exceeding more than 4,000mg in a day.

Original method from Dr. Syed Haider:

  • Start with the low end of 8 grams per 100 lbs and then take an additional 5 grams every 15-30 minutes until diarrhea hits.
  • Example by weight: 200lbs -> 16 grabs initial, followed by 5 grams every 30 minutes

Vitamin C to use & avoid



  • magnesium Stearate
  • silicon dioxide
  • anything else listed in inactive ingredients
"I prefer to avoid any additives if possible. So just ascorbic acid 1000mg in vegetable capsule without magnesium stearste or silicon dioxide or anything else listed in inactive ingredients. Silicon dioxide especially has been linked to possibly harmful effects on microbiome and nervous system."
- Dr. Syed Haider

Important notes

  • While this hasn't been stated by Dr. Haider, I would consider drinking plenty of water to be a necessary companion to high dosage vitamin C in order to mitigate unwanted side effects.

More info according to Dr. Syed Haider

"For most upper respiratory infections that are mild to moderate 10-50 grams seems to do it. Severe infections like pneumonia people have taken 100-200 grams in divided doses. There is some trial and error involved."
- Dr. Syed Haider
"There are different ways of doing this. Some people need 1 gram, others need way more than 50 grams. I know my own tolerance when I’m sick so I just go straight to 30+ grams and then 5-10 grams every 1-4 hours until the runs hit."
- Dr. Syed Haider
In my family the weight based dosing range is rather wide: 8-18 grams per 100 pounds to take out any mild to moderate infection. 
Other people might find they need more or less. 
A good rule of thumb might be start with the low end of 8 grams per 100 lbs and then take an additional 5 grams every 15-30 minutes until diarrhea hits, which probably signals you’ve hit your max absorption capacity for the day, both in terms of how much will get into your blood and how much the bifidobacteria in your gut can gobble up to multiply their numbers.
- Dr. Syed Haider
Oxalate and ascorbate intake
Kidney stones: calcium oxalate

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Jamie Larson