Teneryl is safe to use if taken in the dose and duration prescribed by the doctor. However, in rare cases, some serious side effects can also be observed. In some people, Teneryl may cause inflammation of the pancreas (pancreatitis) which could be severe and can even lead to death. If you experience severe and persistent pain in your stomach area (abdomen), stop the medication and immediately contact your doctor. Teneryl can also cause heart failure. This means the heart is not able to pump blood well enough, therefore, inform your doctor if you have or ever had heart problems before you start taking Teneryl. In addition to that, problems related to kidneys should also be discussed with the doctor.