I started taking Niacin 500mg.( over the counter drug) twice a day 3 days ago and I am having stomach problems. I was told by my doctor that I should take with a meal which I have done. Also, he said it may cause hot flashes and yes it does in the night, but no during the day. AS for the stomach problem, I feel bloating and belching or burping is happening. It is a very uncomfortable feeling. I do have Chronic kidney disease stage 4. I was on Crestor for sometime, but ended up very ill and in the hospital for a month with Rhabdomolysis. Had to learn to walk and use muscles all over again. Can you give me any suggestions concerning Niacin?? You can e- mail me at YYYY@YYYY Oh yes, I am 73 years young!!! Thank you, Karen