At what point does Vit D3 become toxic?

Hi, after my last blood test it was identified my D3 was low at 39 (not deficient, just low) and my new GP suggested I take supplements. It started on 2 x 1,000 I.U.s a day, and the pain I've had in my Achilles for 20+ years went away after about three weeks.

As I'm aware too much can be toxic I maintained the 2 x 1,000 for a month then reduced it to 1 a day, but the pain has slowly returned, though nowhere near as bad as it used to be. I've gone back on to 2 a day and the pain has started to reduce (after just 3 days).

The question I have is, can I continue to take 2 x 1,000 indefinitely, or do I need to alternate between 1 and 2 per day? I have no idea at what point toxicity occurs and google has come up with numerous suggestions of widely disparate values, the lowest of which would put me in my coffin by taking 1,000 I.U. a day! I'd ask my GP, but why waste the NHS's time and resources when I can get a quicker response here :-) But when I have my next Thyroid blood test (08:00, a week on Tuesday - blimey, I never get up that early!) I'll mention Vit D and see if they'll test it at the same time.

Hmm, I may have to change my name from Achilles Pain if this improvement continues.

Thanks in advance.

29 Replies

  • If your VitD was tested in nmol/L then is it VERY low. It's 15.6 in ng/L - and should be around 50/60 as the chart below indicates ....

    As you can see from the first chart/website a dose of 4000 IU's would not be unreasonable. Take D3 with good fats as it is fat soluble.

  • My vit d level, taken in last December converts to 17.6, so very low. The hospial who tested it said I should get supplements from my gp but he said it was, 'perceived as adequate!' It was another 2 months before after advice on here led me to start supplementing with subsequent improvement. Along with b12 etc, and pain has reduced significantly.

    I think GP confused the nmol/L and ng/L so you do need to watch out and know the differences because they don't! At leasr that is what I'm saying, trying to give him the benefit of the doubt. Mind you I take 5000 IU on alternate days with K2. Think that is ok. :-)

  • Sounds good - especially as you are feeling better :-)

  • Hi! My Vit D came back as 37 last October and my GP prescribed 3200 I.U a day. It went back to normal after a couple of months and my knee pain stopped. However, just had a blood test done (June 2016), and my Vit D is now 37. One of the GPs at my surgery prescribed 3200 I.U a day again. However, I spoke to another GP at the same surgery a few days later and she said she would nit have prescribed Vit D. She would have asked me to buy 1000 I.U Vit D from Holland & Barrett. She also said you should take Vit D from October to March (winter time).

  • Generally you need about 2000 iu a day to maintain decent d3 in winter (which is about Oct to May in the UK - there is a web site somewhere where you can work out when you need to supplement as it has to do with the angle of the sun over the horizon). You probably also need to supplement in Summer to, unless you sunbathe a lot without sunscreen. I think it is unethical of GPs to recommend a retailer.

  • Thank you. My thyroid is quite underactive at the moment, so I think my vit D defiency is related to this anyway. Seeing an endo next week, so hopefully will get it sorted.

  • I have worked on 75 being replete and my recent reading was 96 and was said to be good.However,I won't be pushing it any higher as I think that it's not a good idea to go above 100 upwards.....someone correct me if I'm wrong please. As Marz has said...........remember that Vit D is fat soluble.It should be taken well away from your thyroid meds.I take my Armour early morning and vitamins at lunchtime.My Endo said that if there is no fat in your meal to take it with some buttered toast !! I take 1000 IU once a day and have just finished a bottle of 100 Solgar soft gels to get to that level.Before that I was low too. I don't eat bread now so just put a nob of butter on my vegetables .....yummy.

    PS .....your doctor will probably just tell you to get out in the sun .......that's what I was told!! They don't seem to make the connection between low vitamin levels and hypothyroidism.!!

  • When you say 75 is replete, I take it that is in nmol? Or do I need to get to that in ng/l?

  • Just for info, the reference ranges for vitamin D when I've been tested have been :

    From Blue Horizon testing :

    <25 nmol/L : Severe Vitamin D deficiency

    25 – 75 nmol/L : Borderline ranging to insufficiency

    75 – 200 nmol/L : Optimally replete

    >250 nmol/L : Possible toxicity, if sustained

    From NHS testing :

    Less than 15 nmol/L : Deficiency

    15 – 50 nmol/L : Insufficiency (consider supplementation)

    50 – 140 nmol/L : Adequate

  • Isn't it strange that when my gp tested it again in February it was 42 nmol/L which is clearly insufficient, yet he said adequate! Thankfully I took advice from here and supplemented.

  • My NHS testing is at the same ranges as Blue Horizon.

  • That means the NHS has actually managed to improve at something. Hooray!

  • Unfortunately it is area specific.

    So in some areas 50nmol/L is adequate there as in London, parts of SE and Lincolnshire 75nmol/L is.

  • Yes ....nmol/..........when my reading was low a couple of years ago my result read Vitamin D (250H) 49 nmol/L

    Comment.......25-OH VitaminD between 25and 50 nmol/L indicates insufficiency.

  • AchillesPain,

    There is possible toxicity when vitD is >250nmol/L. Toxicity is very unlikely if you are taking <4,000iu daily. I think 2,000iu daily is quite safe.

  • Regarding toxicity of vitamin D, you might find this link interesting :

    Some wittering on my own history with vitamin D :

    My level was 69 nmol/L in May one year. Almost perfect by most people's standards, but I'd read it was better being around 100 or a bit over. I took 1000 iU vitamin D3 over the next few months. I tested again in November of the same year and my level had dropped to about 50 nmol/L - over the summer when our levels are supposed to increase. I had a dog at the time and had been walking her regularly, twice a day, so I was getting ample daylight every day.

    I increased to 3000 iU and my levels started rising very slowly. It took 18 months to get my level up to about 100 nmol/L. (I now wish I'd taken more and got my level up faster.) I maintain my levels with a dose of 2000 iU per day.

    Based on my own experience I consider 2000 iU - 3000 iU to be an extremely modest dose. How anyone ever gets their levels to rise on what doctors prescribe (800 iU per day) just baffles me.

    Edit : I should add, that even though my vitamin D level was never horribly low, I found that getting it higher reduced muscle and joint pain immensely. I hadn't realised until it stopped how much I had begun to hobble and walk like an old lady. I now walk quite smoothly and fluidly. It is so much more comfortable.

  • Thanks everyone, I'll stick to 2 x 1000 I.U. per day as it does appear to be working and if it isn't going to cause toxicity it seems the thing to do.

    The 39 quoted was nmol/L, my GP said it should be 50 minimum. He seemed surprised it was low, saying "it's usually caused by an autoimmune disease that can be brought on by hypothyroidism", also saying I don't have the autoimmune disease as there are no antibodies. Presumably he was referring to Hashimoto's, but he didn't mention any names.

    If I continue taking 2 x 1000 (one with my breakfast, one with my tea), any suggestions how long it may take to get to normal? I do usually appear to respond quickly to change in meds (2-3 days when levo increased from 25 to 50 and 3 weeks when I started D3). Just curious, not desperate for an answer.

    Just hoping my next blood test shows I need an increase in levo as some of the symptoms have returned in the last month or so - I go for a run and the double vision kicks in before I even reach a mile, haven't had that since December. If not then maybe the GP will let me trial 75 for a month to see if it works anyway? Fingers crossed!

  • Achilles_Pain,

    2,000iu daily will take a long time to raise your vitD to 75-200 which is the replete range. I'd supplement 5,000iu daily for 2 months and then reduce to 2,500iu alternate days and retest in 4-6 months. Take vitD with the fattiest meal of the day as fat aids absorption.


    I am not a medical professional and this information is not intended to be a substitute for medical guidance from your own doctor. Please check with your personal physician before applying any of these suggestions.

  • 2000 iU is a low dose for someone who is deficient/low. Your levels may never rise. Why don't you take 4000iU per day as Marz suggested?

  • I'll stick to 2 x 1,000 until the blood test next week and hope they test my D3, see what it's raised itself too. I do seem to respond fairly well (my TSH came down from 9.75 in Nov to 2.75 in Feb when I was on 50 mcg) and the pain I've had for 20+ years went within three weeks of starting on 2 x 1,000 - if it hasn't increased by much I'll try taking more for a while.

    I just don't like taking drugs of any description (apart from my three shandies on a Sunday night down Wetherspoons.

    Last year when I was at my lowest ebb I was living off paracetamol and ibuprofen just to reduce the pain sufficiently to get out of bed, but since changing GP and being put back on levo I've taken paracetamol twice, and that's it.

  • VitD is not a drug :-)

  • They will only test vitamin D levels at 6 months intervals in adults if you start of severely deficient. That is a level under 25nmol/L.

    As you are insufficient either the GP will refuse to test it or the lab will reject it as it is too soon.

    One reason for this is vitamin D rises slowly even if you are supplementing enough. (And you aren't.)

    Another is to save the NHS money. The guidelines in all areas are that if you are insufficient to give "lifestyle" advice and not to test again.

  • I wasn't aware of that - let's see what the nurse says in a weeks' time when she's sticking a needle in me :-)

  • It seems you have not looked at the link I posted for YOU :-)

  • I have read them, thanks, and yes, I know Vitamin D isn't a drug, I was speaking generally as I don't like taking anything, including supplements.

    The converter on the first link states 4000 would be sufficient for 50% of people, 6,000 for 90%. The required dosage will vary from person to person and efficacy will probably be a bell curve. Given how I've responded taking 2,000 (the pain of over 20 years went completely after 3 weeks and when I reduced to 1,000 it came back slowly but started to go again after just three days back on 2,000) I may well be at the lower end of the curve, hence my decision to stay on that dose until I see the results of my blood test - why put more inside myself if I don't need to? I've also increased the amount of fatty fish I eat from once or twice a week to twice or thrice a week and increased the volume of nuts, eggs and cheese I eat. I've always eaten these foods, but I've just increased the amount. I'm also a runner (of sorts) so I'm out in the sunlight all the time in a vest or T Shirt and shorts when all around are still wearing their winter woolies.

  • Do you run between 11am and 3pm between April and October in an unpolluted area without suncream?

    If not being outside won't raise your vitamin D level by much if at all.

  • Yes to unpolluted (I live on the coast and do a lot of fell running, too), sunscreen on my shoulders and nose when I remember, but not my arms or legs, the time and duration varies throughout the year.

  • My GP won't even test for Vit D for some inexplicable reason... When I asked why not they just shrugged their shoulders and said: 'We just don't...'

    So, unless I get it done privately, which I cannot afford, I'm just going to have to guess and supplement. I take the DLUX 3000iU oral spray, admittedly, when I remember... which is not necessarily every day.

  • Vitamin D testing is considered to be expensive by the NHS. And doctors have been told that almost everyone is the UK is likely to be deficient. So their logic seems to be "Why bother testing when you can guess the result?"

    The problem with that of course is that lots of people will never learn that their vitamin D is deficient so they won't think of buying supplements. And even if they do they'll probably just buy a supermarket multi-vitamin which is just a waste of money and wouldn't improve levels of anything much.

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