Pradaxa
"Downside for me with Pradaxa was severe acid reflux.  Neither my doctor nor my pharmacist told me until I complained of this that Pradaxa works in an acidic environment so they put acid in the capsule.  This was particularly difficult at night. I was taking Tums by the handful.  Within a day of not taking it, the acid reflux disappeared.  I'm now trying Xarelto.  So far, no upset stomach."