My head is KILLING me as I type this. I am prone to migraines as it is and have done well in recent years staying away from my triggers so it was a mystery to me why this one started 3-4 days ago. The only thing that I changed was switching from Nioxin to Keranique. So I did a search for "keranique headache" and boy did I find what I was looking for. Not only that, but my eyes have been bothering me and I didn't connect it to the minoxidil in this product until I saw that is was a side effect right along with the headaches. And weight gain! I will continue to use the shampoo & conditioner because I really do like it but I will stop using this product and wait a few days for it to clear my system and switch to the follicle booster instead, that does not contain minoxidil. I understand I won't get the hair regrowth without this product but it's not worth the pain. Also, my scalp is read, painful and itchy.