DRINK TONS OF WATER BEFORE YOUR BLOOD TESTS. I have never had a problem with blood drawings before but this stuff dehydrates you so much that they spent like 10 mins poking around in my vein, gave up, had me drink a huge bottle of water in the waiting room, then tried again half an hour later in the other arm, and after another 10-15 mins of poking and needles wiggling in my vein (ugh! I'm not scared of needles but it was AWFUL) they finally got a few drops of blood out of me, enough for the tests to be run. I didn't even feel thirsty. It really underscored for me how important hydration is when taking this!!!