Vitamin D - prescription

I was prescribed 50000 iu of vitamin D taken weekly for 16 weeks after my bloodwork revealed my levels were low (23). I have read that all prescribed vitamin D is D2. If D3 is better why is the prescrition form D2. Would I be better just taking more of the D3 supplements?

I am wary of taking man made as opposed to "natural" products. Am I worrying needlessly?


Edited November 30, 2008 at 12:36 pm

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My endocrinologist did not think there was much difference between D2 and D3. I would just follow your doctor's advice to get your D up to where it should be and then perhaps try to get out in the sun more (I'm talking when the weather gets warm!) and eat more foods containing D (which you should be able to find out about by doing a google).


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Hi -- I'm prescribed Vitamin D 50,000 IU on alternating Mondays, but it's Vitamin D3. I asked my pharmacist if I could just buy supplements, and he said I'd have to buy bottles and bottles -- just wouldn't be possible. It would have been in his self interest to sell me the non-prescription stuff, since he owns the store, so I trust his answer. Also, I started by taking the pill every Monday for four weeks, then the prescription said to alternate Mondays. My Vitamin D3 very quickly went right to where it should be.

Somewhere I read that 50% of American women have levels of Vitamin D3 that are too low. I was also stunned to read that sunscreen, which I use daily (I'm a poster girl for both osteoporosis AND skin cancer), is enough to block Vitamin D absorption from sunshine.

Catch-22. Deja vu all over again.

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I was prescribed the same weekly dose of Vit. D about a year ago; around 3 months later, my endocrinologist said to take it every two weeks. I think this is some sort of standard prescription for many of us with osteoporosid and low Vit. D levels. I live in the Pacific NW and don't get a lot of direct sun, and like many of you, wear a sun block. Some times we just can't win! Michele

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Read the information on the site provided. So now the question would be why do doctors prescribe D2 rather than D3? Seems like you can't trust anything the doctors tell you anymore. Would love to find a doctor who knows about all this stuff and really tries to give his patients what they actually need. I have been to two endocrinologists, one from a very prestigious hospital, and both prescribed 50,000IU of D2.

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Sadly, I believe Kerri is correct. My endocrinologist thinks I'm crazy to try to up my D levels with D3. He says it just isn't "fast" enough to do any good. But he still agreed to test my D levels every 4 months. And I'm still trying to get those levels up to 50ng or above...something the prescription D did in 3 months.

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I took 50,000IU's for 8 weeks of the D2 and my numbers went from 26 to 32.9. Not sure if that was much gain for the 8 weeks considering I was visiting my son in Australia during their summer at the time. The D also made me feel horrible with my blood pressure becoming erratic. I have since stopped taking any D at the advice of my doctors until they can try to figure out what is wrong with me. The D should make me feel better and help with lowering the BP but not in my case. Everytime I start taking any form of D my symptoms get worse. The doctor at Johns Hopkins assured me I would feel great on the D but couldn't have been more wrong. He ordered the last test for D and when it came back at 32.9 he said everything was fine and to continue the D. I no longer see him because he wasn't listening to all my symptoms.

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You can buy D3 over the counter or online
Search for
If you search for
BIO-TECH D3-50 Cholecalciferol 100 Caps - Free Shipping,
You will find that there are many companies selling it at reasonable prices.
The reason D3 is NOT PRESCRIBED is because it isn't a licensed product. It costs money to get products licensed and nobody is going to patent natural substances that are freely available from sunshine and which cost in the region of $15 for a full years supply for the normal person.
50,000 of D2 every other week is NOT SUFFICIENT.
50,000iu of D2 is as effective as 15000iu of D3
The standard way of correcting vitamin D insufficiency is 50,000iu of D3 once a week for 8 ~12 weeks then retest.
50,000iu once a week = 7143iu/daily.
Ideally the human body requires 1000iu/daily for each 25lbs weight. So that suits someone 175lbs. If you are heavier then take a 50,000iu every 5 days to average 10,000iu/daily. That is regarded as a safe upper limit however for short term use this may be exceeded providing regular 25(OH)D testing is continued to ensure levels don't go too high.
The natural primitive level human bodies living near naked outdoor lives in sunny unpolluted areas is 60~80ng/ml. At 60ng/ml human breast milk flows replete with D3 and at latitude 32N it takes roughly 6400iu/daily/D3 to keep breast feeding women at this level. Further north and in winter it may take more.

Dr Davis of the Heartscanblog ensures all his patients take oilbased vitamin D3 capsules and he finds around 6000~8000iu is required at latitude 42N. But people vary, hence the need for regular testing.

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It simply isn't true that D2 the prescribed form is faster at raising 25(OH)D status than D3. Ergocalciferol is the plant form that is used by rats. Human bodies make and use D3. The D2 has to be converted to D3 before we can use it and that takes time and energy. It's also the case that many people are completely unable to use D2 at all. So however much they take it makes no difference whatsoever.
Even when it is absorbed and used Ergocalciferol speeds up the catabolism of VITAMIN d so the body uses it up quicker. If you give equal number of people equal amounts of VITAMIN D2 and D3 the ones on D3 will always maintain higher levels for longer. While the D2 folk will NOT get such a high response nor will it last as long by 15days they will have a lower vitamin D status than they started with whereas the D3 folk will still have effective protection that will continue for another fortnight.

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Kerri -- my prescription actually IS for D3. My post was drawn from an earlier discussion, and didn't include the whole thread. My pharmacist is smart enough to know that D3 rather than D2 is what we need. Although the FDA hasn't approved D3, My pharmacist located D3 in the 50,000IU megadose, and will write a "prescription" for D3 for the doctors who know what they're doing. This actually saves me some money, because the megadoses OTC come in such large quantities that their expiration date passes before you've consumed them all. Also, once my Vit D level went up from 20 to 60 (which it did in the eight-week period I took 50,000 IU on alternate weeks), a new doctor switched me to 5,000IU of D3 daily, which has brought my D level to 70. But if you'll check the other discussions, you'll find a long one in which I questioned why the FDA approved D2 for prescriptions, but not D3. My concern was that people would think D2 was "good" but D3 was "bad." My point was largely missed by those who responded, who seemed to think I was being silly (and also misinformed -- one writer insisted the FDA simply didn't regulate vitamins, which is usually but not always true.) But I'm glad you sent in your post -- I don't think doctors are telling their patients that they're prescribing D2 rather than D3. I checked with my pharmacist, which is how I learned that my original prescription had indeed been for D2, but I got that changed once I learned what was happening.

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@ 2lessparathyroids
You will probably find that using 2 x 5000IU MCT oil based capsules daily will speed up your Vitamin D repletion.
Just snip the ends off the capsules and squeeze the oil onto your skin and massage into the skin. MCT has a neutral odor and is easily absorbed into the skin. Ideally choose a massage spot the sun doesn't shine on as UVA degrades D3. Absorbing the D3 through the skin is the nearest equivalent to making it in the skin and will avoid the problems you are reporting.
Vitamin D3 is used by every tissue in the body so it's important to try to get levels up to 60ng/ml 150nmol/l. At this level your body has a reserve store of vitamin D3. Between 40~50ng/ml you are just about meeting your daily needs and are living on the vitamin D breadline.
Although you can raise plasma 25(OH)D3 levels fairly quickly with a high enough intake, it takes longer before all the tissues in your body have a reserve store so don't think if you've not noticed any improvement in 3 months that's the end of the story. Keep you levels around 60ng/ml for over a year and then you will see better how it improves your general health and immune function.

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Kerri -- I should have added that the posting you're referring to was also written when I was under a misunderstanding from my pharmacist. What he had actually said was that when a patient showed up with a doctor's prescription for megadose D3 at a health store, the health stores were insisting on selling bottles of 100 doses, at a price above the $12 he charges for a year's "prescription" of the megadose D3.

Whether that was accurate or not, I don't know, but in any case, taking 5,000 IU of D3 daily seems to be working well, even though I think the recommended daily amount has been, for years, only 400 IU, which is WAY too low.

Maybe since at long last a pro has responded to my query written so long ago you can tell us -- why has the FDA approved D2 for prescription but not D3?

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Millie -- my current doctor told me that physicians often prescribe D2 megadoses initially because it supposedly increases the D level more quickly than D3. But then, once the D level is in the 50-80 range, they change to D3. He may do that, but in my experience, the majority of doctors stick with D2 and may not even be aware that D3 is what we really need!

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Thanks for clearing that up for me. It IS heartening to know that there is ONE pharmacist in the world who actually knows the difference and is attempting to get his patients the recommended form of vitamin D!!


I TOTALLY agree with you on the fact that everyone just assumes that 'prescription strength' equals 'good' and that no one questions it. Unfortunately, this is perpetuated by the doctors who just simply don't know and who ALSO 'assume' that its better because it comes from the pharmacy.

Unless they have personally researched it themselves, they are getting their information from other doctors and have no way of knowing.

So, the way that they will find out is by THEIR PATIENTS being educated and refusing to take their prescription. (or by wonderful pharmacists like yours who call them back and ask to change the prescription to d3.)

Thanks for putting this up,

Kerri Knox

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The likely reason the FDA has approved D2 and not D3 is because of the same reason they 'approve' or 'disapprove' most things. To make drug companies happy.

D2 is synthetic and therefore able to be patented. D3 is natural and therefore you can't patent it. And just like you said, the drug companies charge 2 to 3 times more for an inferior product that the insurance companies are happy to pay for and the doctors are too ignorant about to change.

Just look at fish oils. Despite the good evidence to its effectiveness, doctors still didn't recommend fish oils until the drug companies came out with a prescription form, now everyone is taking prescription fish oils because their doctor has a prescription pad and is educated by drug companies who promote their products. They are NOT educated by the research.

And even those doctors that DO read tons of research, where do they start? There are THOUSANDS of studies reported every year (probably 10's of thousands). So they have to 'filter' it somehow.

And they most often get it 'filtered' by those who have a financial interest in getting their product promoted.

I've seriously thought about getting a whole presentation going and going to doctor's offices with donuts like a drug rep and teaching docs about Vitamin D and selling them some megadose D to sell at a small profit to their patients instead of prescribing.

Maybe someday.

Kerri Knox

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Ted and Kerri,

Thanks for your suggestions regarding my problems with vitamin D. My doctors would never even no to give me this advice. The only concern I have is if I still have another parathyroid adenoma. I will wait for my most recent blood work results and then go from there.

Again, thank you both so much. I say this all the time but this site is so great for all of us trying to figure out what to do when our doctors are at a loss. So much useful info.

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Ted: I found the advice you gave to rub the D oil into your skin fascinating. Does this really work? And could you tell us where you got your expertise? Are you a medical practitioner of some kind? :) (We actually like med practitioners here.)

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I'm not a health professional. I have my own health problems and needed to find ways of preventing inflammation. Hence my interest in Omega 3, Vitamin D3 and Magnesium. I have access to a university library and so can read the full text of many, not all, papers that are published. I've been following the omega 3/vitamin d3 story for many years now and find it really interesting. If ever you want to know more just ask. I'm happy to share on the full text of papers where possible. It's certainly the case that using D3 transdermally raises 25(OH)D status. It also works with magnesium. Epsom salts or Dead Sea Salts in a warm bath really is relaxing and that is the impact of magnesium being absorbed through the skin calming nerves and relaxing muscles.

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I should also point out that there have been many cases where the doctors PRESCRIPTION is VITAMIN D3 but as there is NO LICENSED PRESCRIBABLE FORM they supply the nearest form they have available. Vitamin D2 Ergocalciferol.
Here are a couple of images of D2 50,000iu capsules and I'm sure anyone who thinks they are getting 50,000iu D3 will recognize them.

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"I am a real doctor however since we are not face to face and in person for all intensive purposes I am not a doctor in this forum,. Just someone with knowledge and personal experience. Yes I been in those shoes! To sum it up What I say in this forum is as-is and is not intended to offer a diagnoses or treatment"

With that said: Before medical school I had an opportunity to take one of the last classes P. Balch taught at a community college. She is the author of several books and one of her books is called Prescription for Nutritional Healiing.
What I learned was amazing a lot of information on vitamins is so out dated that even the official RDA and government data has not been updated in years. (Granted we had a few minor revisions less than 5 in 30 years)
I saw a lot of research that was conducted by the NFL, the NBA and it was amazing. I am going to get to the point I promise. Vitamin D for therapeutic purposes to correct a deficiency etc. Should be taken with a small amount of vitamins which in simple terms enhances and enables the full absorption of vitamin D and this can be done without buying a lot of products.

Calcium, magnesium, and zinc helps increase the absorption and help achieve results faster as much as 25% according to studies done paid for by the NFL.
All that is needed is 1 tablet even if the serving size says take 2. If you want you can take the full serving size.

Other vitamins especially B vitamins should be taken apart. They are great for general supplementation but if you need the therapeutic dose your body can only absorb x amount of the nutrient and it is best to avoid vitamin c and b vitamins. For a few weeks it is best just to take the enabling minerals mentioned above. (Calcium magnesium and zinc.)

I also want to offer some insight on different forms of vitamin D.
Sub lingual under the tongue: No increased benefits seen according to studies.
Gelcap's: Again no increased benefits. However they are easier to swallow.
Cream: Well this one is interesting and has caught my eye. A lot of studies show that medicines or supplements in a cream have fewer side effects than the traditional forms. I have some personal experience here. I have acid-reflux and diabetes and vitamin d is not absorbed well by those who have these conditions. Also diabetics dot metabolize the vitamin well in sunlight. Diabetics also don't covert beta carotene to Vitamin A.
I had a severe deficiency of Vitamin D and I did not get a major increase in my levels. My endocrinologist told me to stop the prilosec. I informed the doctor to look at my chart and check my dosing and history. He realized I cannot stop my prilosec. I mentioned compounded vitamin D cream. He kind of questioned it but we went with it.

The cream worked and I informed the endocrinologist I would be running my d levels every 3 days as I did with the oral form. We were both shocked in how fast the cream worked. The crazy part is this at first it looked like nothing was increasing the first 3 days but on the 6 day it surpassed the oral form levels by 100%.

We both were shocked about how effective this is but old men set in ways prevent a lot of change plus if it don't bring in $$ it is low on the radar screen.

My sister and mother need hormone replacement therapy and when the switched to plant based cream they felt better and had more of the hormones and less of its metabolites in the body. (Metabolites is a build up of chemicals and other substances that drugs leave behind or our body converts to other substances. Sometimes these can be bad.

I intent on writing a new blog on the internet. I also take questions keep in mind they would be general answers. You can email me at
I am just starting out and I do all my own typing and forgive my grammar and occasional spelling mistakes. I dont have a proof reader.

Have a great day!

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With vitamin D3 the "serving size" is not an issue.
If you look at this image
You will see how both D2 and D3 raise status at 50,000iu but the graph shows how at day 4 the 25(OH)D2 level drops significantly and by day 15 status is lower than the starting point while D3 remains above the starting point even 30days later.
If you are using 50,000iu/week = 7100iu approx IU daily this should over 12 weeks raise you 25(OH)D but testing is necessary to ensure that this is actually happening as many people with chronic inflammatory conditions find they may need up to 10,000iu/daily. shows typical responses to different daily intakes. 60ng/ml is the primitive level Vitamin D flows in human breast milk and human bodies living near naked under the sun, maintain vitamin d homeostasis.

Interesting point about diabetics and vitamin D synthesis. I'd always assumed the low vitamin D status led to diabetes and not considered the issue from the other side. Diabetes does lead to increase in several coagulation factors, decrease in natural anticoagulants, so blood flow to the surface of the skin may not be as good, giving rise to the number diabetic skin problems, that could indeed reduce vitamin D synthesis.

Krispin has some good magnesium information here
and she suggests
"5 to 10 milligrams per day per kilo of ideal body weight or 2.5 to 4.5 milligrams per day per pound of ideal body weight." with lower amounts several times a day producing the best results.

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