I have experienced this a bit and I don't agree that this can just be chalked up to your body detoxing. The type of oil that you use is not emphasized with oil pulling but there is actually a huge difference in how your body will react depending on what kind of oil you use. Remember that oil-pulling comes from Ayurveda and Ayurveda identifies various body-types and physical imbalances. Depending on what your situation is you might want an oil that is either heating (sesame) or cooling (sunflower, coconut). I know you said you don't notice a difference with different oils but all this takes a certain amount of time to feel a specific impact. So you have to try out a specific oil and stick with it for a while (maybe a month) to see what kind of impact it will have. I have bad reactions when using sesame oil, good reactions when using sunflower seed oil.