I've been on citalopram 10 mg for anxiety for almost a year now. My doctor upped the dose to 20mg a month ago. The past week I have been having troubles with my heart beating rapidly and my chest hurting and feeling tight. It is causing me to feel anxious. I'm not anxious about any one thing it's just my heart rate making me feel anxiety I think.r It doesn't slow down even when I do deep breathing. So I'm wondering if anyone else has experienced anything similar. Is this a side effect? Is my body just not adjusted to the higher dose yet? If anyone has any input I'd love to hear it.