When I wanted to get back on my vitamins during chemo treatment I took them all to the cancer pharmacist and the only thing I couldn't go on was Vitamins C because it's a blood thinner. My Calcium Plus from Costco has magnesium in it and that was fine with the pharmacist. I wasn't even allowed a protein supplement to put in my smoothies because of the ingredients. There are 4 cancer pharmacists and I could call them anytime I wanted which sure helped me. I figure it's always best to check with your cancer team in case of interactions with your meds.

I hope it helps. I was dx with fibromyalgia, thought I had Lyme disease. The rhumatologist asked if I had been under any stress? Just cancer treatment, does that count!

I take 800 a day. I started taking it on recommendation from my heart doctor to help with racing heart beat (pcv's) problem I was having. It also helps my neuropathy leg pain and if I get constipated from pain meds I take an extra one and it helps. Of course you should stick with recommended dose. I was low when they tested my blood so that is why I take more.

My oncologist prescribed magnesium for me while going thru chemo so in his mind, it must have been OK.

I wasn't allowed Vitamin C before surgery either because it has blood thinner ingredients in it. Between surgery and starting chemo I went back on Vitamin C then had to stop once starting chemo. The oncologist went over all the best foods to eat to get natural vitamin C and he also stressed to me to take Vitamin D.