I am going through tests for possible ms. i am supposed to take 5, 000 mg of vitamin d. is this harmful or are there side effects?

Yes if mg, no if iu: I am almost certain your doctor advised 5000 iu of vit d3, not 5000 mg. 5000 iu equals 0.125 mg so 5000 mg would be a very toxic dose! 5000 iu might be a bit on the low side- most adults need 5-10, 000 iu/day to achieve optimal levels of vit, d and such doses are perfectly safe. See http://bit.Ly/1dc7vna ; http://bit.Ly/1ekkvkv it has no side effects but it is wise to also take 1 mg/day of vit k.

A few comments: At your age of 71 yrs, the possibility of presentation of multiple sclerosis is frankly very remote, but in my experience, not impossible. Yes, virtually all my ms patients do use vitamin d-3, at 5000-10000 units daily, and we aim for blood levels at about 50-60 ng/ml. Not clear how high levels can go prior to toxicity, but this is a fat soluble vitamin, and may have toxicity over time.

Vit D & MS: This is a high dose of vitamin D, but it is not likely you will feel any side effects. Some people take this dose or more every day. Excessive vitamin D may cause a change in your taste, nausea and vomiting, or changes in mood or thinking. These are rare. Good luck with your tests. May they yield encouraging results!