CLL Support Association

Vitamin D toxicity

I have CLL with 17p deletion and recently finished a six-month course of obinituzumab and chlorambucil, which was only moderately successful. My energy levels didn't recover at all as had been predicted so I asked my GP to test my vitamin D levels. At 43, my levels were just below the normal range of 50-150. He prescribed a loading dose of six Cal D Forte 1.25mg tablets (Vitamin D3, I believe). Within a couple of days I was absolutely floored, and could hardly get out of bed. This lasted a week. Nearly three weeks later, my energy has improved but not back to the levels I had before I took the supplement. The side effects are said to include "unusual tiredness and weakness". I have found a few people on the net who had a similarly dismal response. Has anyone here had a similar experience?

12 Replies

Cannot help re vit. D but I hope you are soon fully recovered.

Best wishes



I had a similar experience with Vit D. Made me so tired that I started taking it before going to bed but the next day I felt almost hungover which didn't wear off until mid pm. I told my GP but he dismissed it.

Eventually my GP stopped the prescription and told me to buy a specific make from Holland & Barrett. I bought some but had the same effect so I stopped taking them and I feel so much more aware and awake. Just waiting to see if my levels drop again. When I was originally tested my level was just 13!bi am on W&W.



Thanks, NooNoo. My haematologist dismissed it too.


Very frustrating!


That's strange, I've heard the opposite is true, taking VIT D3 supplements is supposed to give you energy not take it away. I take my D3 in oil capsules as Chaya (CLL Topics) mentioned that it's easier to assimilate that way.

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My Gp prescribed pharma grade vit d for me because my levels were consistently low even though I was taking commercial d. This wasn't geared to my CLL. I felt GREAT! He said he had the same results with people dealing with fatigue. Now that I am reading about D levels and Cll I may ask about going on it again.


Your comment reminded something I read published by Grassroots Health, an organization whose focus is only Vitamin D. An author commented that giving large bolus doses of Vitamin D is not particularly effective and could cause problems. Here is the website:

Vitamin D3 has done wonders for me. I don't know where in the world you are and I understand that in many places one cannot buy Vitamin D3 capsules (not tablets, don't take those - not easily absorbed) in a olive oil base in 5000 iu strength. That is what I take. Mornings are best to take them, with some fat for absorption and with Vitamin K.

Hope this helps.


Sorry to answer your question with several questions but more information is needed. Was your vitamin D level a 25-OH vitamin D or 1-25 dihydroxy vitamin D? Were the units of measure nmol/L or ng/dl? What is the total number of units per day of D3 you are taking and are you sure it is D3 and not D2? What is the total number of mg of elemental calcium you are taking in one day?


The lab form said: "25 OH Vitamin D Vitamin D (25 Hydroxy)"

Measurements were nmol/L (mine was 43)

The tablets were Cal D Forte 1.25mg. I was told to take six at once as a loading dose (but in fact I took one a day for six days, fearing it might be too much in one hit). I was floored by fatigue a day or two after my final tablet.

Three weeks later, I'm starting to feel as normal as my CLL usually allows.


I asked to have my vitamin D level tested in 2010 when people like Brian Koffman started talking about it. My doctor started my on prescription D2 - 50,000u a week. Based on what I was reading I asked about changing to D3, which is over the counter in the US. It took two years of playing with the dose and checks every three months to find the right dose to kick my level up and then keep it in a healthy range. I wish I could say that it made a huge difference in the way I feel. I do think it helped with bone and joint pain and my bone density numbers improved. However they were down a bit recently, so ??? Work with one of your doctors (I work with my PC) to monitor levels and make needed adjustments. All of my doctors - PC, hematologist, nephrologist, endocrinologist, cardiologist - want testing. I have become good at scheduling labs so I can have various tests done once and reported to everyone.


Thanks, Kpenn. I have been so knocked about I'm fearful of taking any more Vitamin D for the moment so I'll wait to see what the tests show.


I would definitely have labs done before adding ant thing back. If your level is still low talk to your doctor about adding D3 back slowly. In the US you can buy the gel tabs in various doses, so if you start on a low dose it's easy to hp the dose by just taking additional pills until you establish a level that works for you. Also make sure you aren't taking other supplements that also contain D. My doctor added something with D, so I had to adjust the straight D supplement to keep my intake the same.


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