Holy Shiite Batman !!!
So much information about vitamin D3... Some of it spot on and some of it so far off base it's meaningless BS that only serves to confuse, or worse yet, frighten readers new to this regimen.
For starters, vitamin D3 is one of the safest nutrients we can take. It's so important to human biological functions, our skin makes vitamin D3 when 7-dehydrocholesterol in the fatty layer of our skin is exposed to the UV-B in sunlight. Moreover, a vitamin D3 dose of 10,000 IU/day is very safe.
The important thing to remember is it isn't the dose of vitamin D3 that counts, but rather the 25(OH)D response. As we all respond to vitamin D3 differently, it is always prudent to see your PCP or neurologist for a lab test of your 25(OH)D.
Over 300 member CH'ers here at CH.com have posted they started the anti-inflammatory regimen over the last four years and there has yet to be a single post from any of them indicating vitamin D3 intoxication. Given the number of guests reading the main post on this regimen, I'd estimate at least another 300 guests have also started this regimen.
Data from the online survey of 127 CH'ers taking this regimen to prevent their CH indicates 83% of the participants experienced a significant reduction in the frequency, severity and duration of their CH. 60% of them reported they've remained pain free while taking this regimen, yet none of them reported any vitamin D3 toxicity.
A recent open label year long RCT involving 45 people with remitting recurring multiple sclerosis (RRMS) taking escalating doses of vitamin D3 from 4,000 IU/day up to 40,000 IU/day and a 25(OH)D maximum response of 410 nmol/L, (164 ng/mL) in six week increments resulted in no cases of vitamin D3 intoxication.
The average adult with fair skin can generate 15,000 IU of cutaneous vitamin D3 in as little as 10 minutes if exposed to the UV-B in mid day sun, clad in a bathing suit without any sun block.
Our bodies also have a number or regulatory mechanisms that maintain vitamin D3 and its metabolites at the proper concentrations even when we take a mega dose of 1 Million IU vitamin D3...
Regarding medical conditions where the anti-inflammatory regimen's vitamin D3 is possibly contraindicated... there are only two... Hyperparathyroidism, where an excess of parathyroid hormone in the bloodstream due to overactivity of one or more of the body's four parathyroid glands and sarcoidosis, an immune disorder.
If a CH'er had either of these two disorders, they would be well aware of any sensitivity to vitamin D3. I've been in contact with one CH'er with sarcoidosis and she worked with her doctor to find a safe and effective dose of vitamin D3.
The other two possible contraindications occur if a CH'er is taking a blood thinner like coumadin, (warfarine) a.k.a. rat poison... or taking verapamil as a CH preventative.
In the case of blood thinners, taking vitamin K1 requires close medical supervision... However, if you read the list of supplements in this regimen, you'll see that vitamin K2 is suggested... not vitamin K1. Vitamin K2, a.k.a. the menaquinones, MK-4 and MK-7 have no impact on blood clotting...
In the case of verapamil, taking calcium supplements can in some cases, reduce verapamil's effectiveness as a CH preventative... I look at this possible contraindication in simple terms... If verapamil isn't effective in preventing your CH, taking the anti-inflammatory regimen isn't going to change verapamil's effectiveness... but this regimen could help prevent your CH.
Can you take too much vitamin D3? Of course... you can also drink too much water and that's proved fatal for a few people with a complete lack of common sense who took a dare to drink a gallon of water...
In the history of the FDA's database of adverse reactions, there hasn't been a single death attributed to vitamin D3... Unfortunately that cannot be said for verapamil, sumatriptan succinate (imitrex), prednisone, lithium and all of the anti-psychotic medications prescribed for cluster headache.
Is vitamin D3 used in rat poison? Yes, but you need to read the label carefully. For starters, this form of rat poison is used to combat anti-coagulant resistant rats and mice... In simple terms, these rats and mice are resistant to warfarin a.k.a., coumadin, another rat poison frequently prescribed to people to prevent blood clots...
What is really interesting is the vitamin D3 (cholecalciferol) Rat LD50 oral = 43.6 mg/kg by weight. The LD50 is a common measure of toxicity where a lethal dose (LD) results in the death of 50% of the animals taking the substance.
As the average rat (Rattus Norvegicus) weighs 300 grams, (~10.5 ounces), the LD50 works out to 13 grams of vitamin D3.
In order to convert the 13 grams to International Units, (IU) we first convert grams to micrograms (mcg). As 1 mcg is one millionth of a gram, we multiply the number of grams by 1,000,000 so that works out to 13,000,000 mcg of vitamin D3.
As one mcg of vitamin D3 equals 40 IU, we need to multiply 13,000,000 mcg of vitamin D3 by 40 to convert to International Units (IU). Doing the math... 13,000,000 mcg X 40 IU/mcg = 520,000,000 IU of vitamin D3... Yes, a 10.5 ounce rat needs to eat 520 million IU of vitamin D3 to reach the LD50.
To put that in further perspective in more familiar terms, a 10.5 ounce rat could eat all 300 of the 5,000 IU vitamin D3 liquid gel caps in a bottle of Nature's Bounty vitamin D3, 1,500,000 IU, and the only thing that would happen is you'd have a very healthy rat... In other words, it wouldn't hurt the rat...
I don't know about you... but I find it amazing that a rat needs to eat 520 Million IU of vitamin D3 in order to reach the LD50 dose... The way I see it, if a rat eats half that much, you've got a very healthy rat...

Remember, the suggested maintenance dose of vitamin D3 is 250 mcg/day, or 10,000 IU/day...
A few other LD50s for humans to ponder...
The LD50 for water is 6 liters
The LD50 for alcohol is 13 Shots (1 shot = 45 ml, of 40% alcohol by volume).
I hope this discussion puts the safety of vitamin D3 at the doses we take to prevent CH in perspective...
Take care,
V/R, Batch