This seems quite odd Tim. We don't ever get complaints from customers about having headaches using our whey. I am not being dismissive, but one experience is far from conclusive in linking the use of the whey protein to the headache. Headaches can be attributed to a combination of factors. The only ingredients we use in our WPI are whey protein isolate, sucralose and cocoa (for chocolate based flavours). If you've used a product before that contains these ingredients and didn't experience something similar, then it is unlikely that our WPI caused the headache. That being said, I would advise you see a medical practitioner who is in a better position to assess health problems.