Does vitamin D supplementing make you tired ?

Does anyone else find that taking vitamin D makes them really tired . I find it very hard to take any amount over 1000iu , I get very sluggish and my joint pain is more pronounced . I know I have to raise my levels but at 1000iu a day it's going nowhere . I have tried , drops , tablets , oil capsules and all have the same effect . ..


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36 Replies

  • I've recently increased my daily dose of vit D to 5000 iu per day. I have noticed being more tired, but I don't know if it is caused by the vit D. I also noticed some improvements.

    I did wonder if vit D increased the absorption of calcium and the calcium caused this.

  • You should have a calcium blood test before taking high doses of Vit D because it will increase your calcium level and you don't want it to go over the range, high calcium is not good and may be caused by parathyroid disease.

  • Thanks for the replies , my blood calcium level is low so I am ok to take the large dose vit d , it's the fatigue when taking it that stops me every time .

  • It makes me very tired. So much so, it helps me get a great night's sleep. I have it either with my evening meal, or some coconut oil or milk before bed. (oil helps absorption)

  • I am in the same boat. I find vitamin D3 is practically a sleep med for me. I only ever take it at night now because of the effect it has on me. When I was first prescribed it along with other meds & supps, I was falling asleep at work every day. I would take my vitamin D just before I left home each morning. The fatigue from taking it was over whelming. I had to hide at work to sleep it off. After a while I realised it was not my health worsening but the vitamin D that was wiping me out. My vitamin D levels were low. My levels of the active form of vitamin D (which dont usually get measured) was normal though.

    This issue of a vitamin that I was low in wiping me out was really frustrating, and I'd love to have the answer as to why as it may give me more answers to my health issues. I am going to experiment now with taking natto for breakfast each day to get vitamin K2/K7 levels up.

  • Yes , I did have electrolyte tests including calcium. My calcium levels were fine. My vit D levels were insufficient and I was actually told to take 10000 iu a day.

  • Hi Jow11, I was told by my GP some time ago that increased calcium absorption causes calcium deposits under the skin. I have a calcium deposit under my skin but my calcium levels are fine! Just a thought...

    Jo xxx

  • I think this is one of the reasons vit k2 is recommended alongside vit d , I believe it prevents calcium deposits in places they shouldn't be . I am sure someone more knowledgeable on the subject could explain it better than this .

  • Hi Avalynd, thanks for replying to me and your explanation.

    Would it be worth testing for Vit K2? Would a GP test for it? Not sure how much more testing I can take at present!

    Jo xxx

  • I am not sure there is a test for K2, maybe someone else might comment on that . It was just explained to me that I should take K2 alongside the vit d to prevent calcium deposits in soft tissue etc . I googled it at the time and there is a lot of material on the subject . Best of luck x

  • Ok, cool. :) Thanks for letting me know about this!! Good luck in taking the K2 with the Vitamin D!! :) Jo xxx

  • Thank you for your reply. I did have a calcium test and my levels are fine.

  • Yes, same here. My Calcium levels are fine. Glad to hear yours are too Jow11. :)

    Jo xxx

  • Hmm interesting,been feeling more tired too but not sure if it's connected. I've been on 5000 u x day for a month. Really makes you wonder.

  • Crikey, do you need to take that much? I bought some the other day & it's only 25 per tablet!

  • HarryE I think 25 equals 1000 iu which is international units I believe. I was taking that before the gp gave me a prescription for 5000.

  • Oh OK, that's not too bad then. I thought I should be taking the whole bottle! :-)

  • lol, my levels were so low , the doc prescribed 50,000 mg a week for 4 weeks. After that it was 2000 a day for a month that I'm on now. Then they will test again. The scale they use is 20 being lowest and 50 highest. I was a 22 and felt miserable, but now I'm at 44 and feel better but the 2000 makes me tired. vitD absorbs into your fat so it sticks around a while, I"m wondering why it makes me sleepy. The first round of 50,000 knocked me out and i had to take the day off work, but it got better after. Maybe just an adjustment?

  • Hi Emily - cant we take the VIT D at night rather? I have started with a VIT D mouth spray today one spray = 1000 IU - but after an hour i really started to feel lethargic - just a suggestion - Just explained to me what the fat has to do with it ....... i am over weight and it might make better sense to me :)

  • Just my thoughts, for what it's worth...

    Vit D doesn't make you tired (doesn't sunshine have the opposite effect? except in cats) perhaps there's something else going on/needed as well, (Mg and K2?) after all this is just one of many vital minerals that tend to be low/affected by slow metabolism/HypoT - it's tricky - I started with one & realised things work together.

    How many of us are tested before taking supplements? I am guilty of taking B12 to help & tests were fine (after) J x

    PS my shins hurt even more for a while - took me a few months to feel any benefit, but worth it.

  • Thanks , I was tested before I took any supplements , my vit d level was pretty low as was my blood calcium . I guess I will just have to stick with the 1000iu fir the moment and continue with the k2 and magnesium . Oh and on a lighter note , sitting in the sun makes me sleepy so I must have been a cat in a former life , lol :-)

  • I think I must have been a cat too! there was a discussion a while back about taking it early on otherwise it could help cause insomnia. It did think it was being Hypo that made me tired but less so now I'm maintaining a decent Vit D level. :D

    PS low iron is another suspect.

  • My doctor said the same thing, that it shouldn't make you tired, but yet something must be going on because it fatigues me too. I'm getting a second med opinion soon.

  • Hi,, do make sure your not taking your vitamin d anywhere near your thyroxine,, at least 4 hours apart plus vitamin d should be taken with main meal pref containing bit of fat,, if your doing all this and still fatigued, then perhaps get thyroid tested to see if that's ok. do you also know your recent vitamin d level? if all this is fine then perhaps look to take a weekly dose or twice week, perhaps 5000 twice a week ? just as example that is.

  • I too am suspecting that i am get 'negative effects' from taking higher doses of vit d;(5000 - 10 000iu),i much worse hypothyroid symptoms(sluggishness in body and brain.and night waking with a feeling as if my brain is going into a coma!I 've never experienced this before and it is horrible and a bit scary;that it gets that bad.Also,i not conpletely sure ,but taking high dose vit d seemed to be the cause of joint pain.Its difficult to be 100% sure if its the vit d.I need to trial it again but am reluctant!My vit d levels r a little improved since the summer(as i have supplemented)but need go up more.By the way,i have read countless times about the importance of vitk2 when taking vitd.(which i do take:recc dose is 1000mcg of vitk2 per 5000iu of vitd.)

  • Hi Cloud,you mention the head sensations which I can identify with too . I have actually tried vit d now 4 times with the same results so I know for definite it is what causes me extra fatigue and joint pain . I envy people who can just take 5000iu a day with no ill effect . Good luck if you try again .

  • K2 is not tested for in UK, Japan seem to be the only county to prescribe it.

    I take it along with vit D, calcium and magnesium (for osteoporosis ) there are books which explain the role of these suppliments. Basically Vit D aids absorption of calcium into your body and K2 directs the calcium to the bones rather than letting it deposit elsewhere in the body.

    There is a really good book called 'vitamin K2 and the calcium paradox' which explains the link fully.

  • Thanks for this jessiepup , I must look up that book for info . X

  • I cant get out of bed if I take vitamin D. I have tried very low doses,and still have the same results. I also have severe joint pain when I take it. Its not just you,google it. Dont let anyone tell you that its in your head,its not. Good luck

  • I just can't tolerate Vitamin D, I start taking 5,000 IU a day a week ago and start feeling sooo tired since the morning,.. I was barely able to work, after my shift I was feeling like a HUGE achievement I finish my work.

    I don't know why I did have this reaction, but I will start taking magnesium, calcium & multivitamins to see if any improvement, I let you guys know how this thing is going.

    I know the post is very old but I couldn't resist to post :)

  • Don't guess anyone will see this. I'm taking vit. D and very tired. Sunshine also makes me tired. Connection, maybe?

    Rubyxx 😊 😊

  • I took a high dose of vitamin D yesterday and today I feel excessively sluggish, tired and crabby. My brain has not been able to process continuous thought and seems to stop up mid-sentence while talking. I work on the phones and had a twelve hour shift today that I couldn't have gotten through if I hadn't been able to take two naps throughout the day. Vitamin D absolutely causes tiredness. I wouldn't say my joints hurt anymore than usual, however tired is a definite! I am rarely rude on the phones at work, but today was extremely difficult due to how tired I felt and still feel. The best way to describe it is hungover. I feel like I was out drinking all night, but I only had that high dose of D.

  • Go to - I think they are more in favour of taking steady amounts throughout the week rather than one big amount. I was reading something yesterday about bolus dosing in research papers not being a good way to illustrate the positive effects of VitD ....

  • I have found this to be true for me. I can't take vitamin D in any form except sunshine or I'm in bed for 24 hours sleeping it off. It doesn't matter how much I take or in what form I am so out of it! I can't take it at night and have it be gone the next morning. It takes around 24 hours for me to feel normal again. I do get the achy joints too. This isn;t the only supplement I react to different than others. If I take more than 3000 mg of vitamin C I start my period. Its very frustrating. Why am I so weird?

  • Any change in calcium level in blood affects Thyroid hormone absorption/conversion as that is the body's brake mechanism to slow down metabolism( for example for long term reducing heat) done by countering act of parathyroids. This mechanism balances off metabolism in a period of roughly 1-2 months monitoring calcium amount in blood . By getting considerable(it's a unique factor person to person) amount of vitamin D and following increase in calcium, this metabolism brake system is triggered and it'll take the body few months to trade off back. "Vitamin D is actually a hormone and not a vitamin" and taking any sudden amount has drastic impact on bodies as all hormones are to have. Try to take natural amount as much as you can through food sources and sunshine as much as your health stat allows and if going on supplementary, ask your med to go steady ,slow and long run. Maybe that's why we start having gentle shine mixed with clouds at spring before full sunny summer days. Btw for obvious reasons people with more sensitive metabolism would feel more of the turbulence.

  • In my personal experience any dose less than at least 100,000 IU makes me extremely tired and spacy, sleepy and brain fogged. I have tried different combinations of Vitamin D and figured out that I can only tolerate high potency dosage and the best is 250,000 IU shot. I will advice that people who feel fatigued at when consuming 100 to 10,000 IU should try dosages much much higher. In my opinion these are too low and will never ever raise your levels. Further I have also observed that taking 250,000 IU intramuscularly also makes me feel very fatigued despite the fact that it is very high. This phenomenon is unexplained yet to me but I guess this has something directly to do with calcium deposition in tissues by injecting into muscles.

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