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Vitamin d given by doctor

I wrote a letter to my doctor last week. I have not seen her but got a phone call from the surgery saying topic up a prescription for Vit d, it's one off dose and to be retested in 6 weeks.

I have 15 capsules, 20,000iu each.

I have to take them all at once, any advice, time of day?with food?drink? Away from thyroxine?

No instructions given with the medicine.

Will I feel anything afte the dose?

Thanks for reading x

9 Replies

this feels wrong to me - please check.....


I dont think you should take all at once. Some people take 20,000 once a week?But like southlondon say -check



Such doses have certainly been mentioned and used. Have a look here:

(They mention 300,000 injections)


Scand J Rheumatol. 2009 Mar-Apr;38(2):149-53. doi: 10.1080/03009740802419081.

The tolerability and biochemical effects of high-dose bolus vitamin D2 and D3 supplementation in patients with vitamin D insufficiency.

Leventis P, Kiely PD.


Department of Rheumatology, St George's Healthcare NHS Trust, London, UK.



To investigate the practicality and tolerability of high-dose intramuscular (i.m.) vitamin D2 or oral vitamin D3 replacement in vitamin D-insufficient patients, and to evaluate the biochemical efficacy of each formulation.


Sixty-nine patients with vitamin D insufficiency [25-hydroxyvitamin D (25(OH)D) <40 nmol/L] were recruited from the Rheumatology Outpatient Department of St George's Hospital, London. In study 1, 50 patients received 300 000 IU i.m. vitamin D2 (ergocalciferol). In study 2, 19 patients received 300 000 IU oral vitamin D3 (cholecalciferol) under observation. Biochemical response was measured at baseline, and at 12 and 24 weeks.


Bolus i.m. vitamin D2 or oral vitamin D3 was well tolerated. The change from baseline in serum 25(OH)D was significantly greater at 6 and 12 weeks in study 2 (p<0.0001 and <0.0001, respectively). In study 1, a modest increase in mean serum 25(OH)D at 6, 12, and 24 weeks was observed but no patients achieved a serum 25(OH)D concentration > or = 50 nmol/L. PTH remained elevated in 42% of patients with secondary hyperparathyroidism at 12 weeks. In study 2, 100% and 89% of patients had serum 25(OH)D>50 nmol/L at 6 and 12 weeks, respectively. All patients with elevated baseline PTH were fully suppressed at 12 weeks. No cases of hypercalcaemia were observed in either group.


The 300 000-IU bolus of vitamin D2 or D3 was practical, well tolerated, and safe. Vitamin D3 had greater potency than equimolar vitamin D2, with a higher, sustained serum 25(OH)D response and efficacious PTH suppression. To adequately treat vitamin D insufficiency we would recommend administering 300,000 IU oral vitamin D3 approximately three times per year.



Despite all that, I have a possibly irrational dislike of such megadoses.

My choice is to take 1200 to 6000 IU doses. Regularly. But mine is bought over the counter and not prescribed.



I also meant to say:

I am very unimpressed by you simply being given this without instructions, cautions, or anything else. In my view, that is WRONG WRONG WRONG!



Have you had your vit d tested ? if so what was the result ? if you haven't been tested you certainly shouldn't be taking that high a dose without knowing your vit d status.

My vit d level is 12nmol and my Endo said she would normally prescribe a 300.000iu injection but I can't even tolerate 800iu so that would be no good for me.

You also need to know your calcium level and keep a check on it if you take vit d supps.

I wouldn't take anything without checking as this does sound very wrong.


Hi my Vit d is 10mmol, and calcium is ok, and PTH was ok too, had lots of tests, I definitely need high dose just unsure about such a large dose in one, seems a lot to me.

I've been taking 800iu over counter ones with little effect.

Maybe I will wait to take them until I've spoken to GP again.

Like you Rod i thought the dose was an injection, so was suprised, I wonder if there has been an error. Was told its a one off dose, with blood test in 6 weeks.


This is from Pubmed website for your info,I'm not suggesting you go ahead

" To adequately treat vitamin D insufficiency we would recommend administering 300,000 IU oral vitamin D3 approximately three times per year ".

BUT I would definitely check with your GP that is right before taking it.


Phone the surgery and ask for help


It was right guys, al in one oral dose x


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