at first for about a week I had a horrible headache. it didn’t feel like a normal headache either, it felt like a mix between the sinus pressure type of headache and a fever headache. I also was sleeping 3 times as much during this phase, like I’m talking sleep before work, get home the next day and sleep 5 more hours. wake up eat dinner sleep again. but eventually I got passed it after that week or so. felt better ever since. saves a lot of money too.