Hi, I was wondering if Magnesium was a mineral or a vitamin and whether it can cause blood thinning. I am having bilateral knee surgery in 9 days and was told not to take any vitamins for two weeks and no nsaids for the last week prior to the surgery. I am on Ultram which causes constipation and the Magnesium works nicely to help that problem (plus about 10 prunes a day!) I would like to stay on the Magnesium, but not if it will compromise my surgery. if you say that I should not take the magnesium, what else can you suggest. I take fiber (psyllium husk) pills, but without the Magnesium I feel just dreadful with the constipation and have to de-impact myself (using gloves of course). I don t think that is very safe to do as it makes me bleed sometimes. Can you safely take laxatives for a week and what kind would you suggest? Thank you so much for your help. I did ask my Dr s nurse and she said to take Senecot. Any help you can give me would be appreciated. Thanks again. -JSL