I had side effects even on one click - nausea, stomach upset...that is all i could tolerate. But developed neuropathies all over so have had to stop again. But, my calcium levels were rechecked and much lower than every other time I've had it checked over many years. I am guessing the drug was working somehow to pull calcium from my blood and hopefully put into bone...just guessing. I am wondering if the doses they prescribe is higher than it need be. I always wonder too if a much lower frame/body weight person should have a much lower dose.