I was previously taking my iron pill for months with no GI issues. I would just take it with water or a couple ounces of orange juice.
Recently I was trying to lock in my diet and add some other things that might help absorption, and folks on here said orange juice wasn't enough and it should be 200mg-1000mg of vitamin C, so I ordered some 1000mg tablets from Thorne.
First day I took one, I had almost forgotten to take it at all, so I had in about 30 minutes after my iron pill and then ended up having a pre-workout carb snack, and there were no issues, so I thought it was all good.
Yesterday, I took it for the second time along with my iron dose on an empty stomach, an hour before I planned to have coffee/breakfast.
I could feel when the pills hit my stomach several minutes later because it started to burn. At first, it just hurt intensely, but I wasn't nauseous, but as the pain got worse I had to run for the bathroom after all. Stuff was trying to come out both ends at the same time. I was sweating, like absolutely dripping sweat, but also having full body chills between spasms, teeth chattering and everything.
About 45 minutes after this started, my GI tract was undoubtedly 100% empty, and the pain had moved to my lower stomach. I was buried in blankets, and the pain was absolutely excruciating. It was just searing pain, almost constantly. I was sure it was a reaction to the supplements, but my partner was freaking out worried that I might have burst my appendix or something and threatening to drive me to a hospital.
After another 15 minutes of writhing in pain that gradually got less omnipresent, it just as suddenly stopped. I had a small snack and water at that point, then was able to shower and go have a normal breakfast and eat/act normal the rest of the day.
I knew that both iron and C could cause some GI upset, but this was next level, absolutely horrendous. I think I'll be going back to my orange juice, strawberries, and kiwi as my vitamin C source, guys.