"i&#039;ve been taking concerta xl for around 2 months after finally being diagnosed as and adult. i started on 18mg, and within half an hour, i felt able to concentrate and focus on tasks for the 1st time. a couple of days later, i had crippling headaches but everything settled down after that. my resting heart rate has sped up by 10bpm whilst the medication is in effect. i&#039;m currently on 54mg and the therapeutic effects are great, but i feel dehydrated no matter how much water i drink, and i have developed sinus problems. it&#039;s worth it though."