 Some risks associated with the Dexcom G4 System Device have been reported: placing the devices in your skin may cause some anxiety, pain, irritation, redness, and swelling. There is also the risk of infection, excessive bleeding, or hematoma swelling filled with blood caused by a broken blood vessel - these risks are rare. Removing the sensor may also cause some discomfort or irritation because of the tape used. This reaction usually goes away within a few hours, but may last up to a week. There may be some itching in the area, which is a normal healing response. 