Well ive suffered from heart palpitations since I was 17 and im now 27 and dc still cant find out the cause ive had two ECG over the past 10 yrs which both came back fine and so did all my blood tests. Upset. Prednisone does cause depression, as well stays in your system for a long time, but since you were on it a short time it could maybe stay in your body for about 2 to 3 weeks. Effexor is a dual purpose antidepressant released by Wyeth-Ayerst Laboratories and approved by the FDA in October 1997. Effexor boosts serotonin levels in the synapse in similar fashion to other SSRI's. phetermine is bad for u. It causes increased heart rate like efedrin. it can cause palpitations also. I've tried it and it made me panicy, caused my heart beat faster. I'm a 45yo female with undiagnosed debilitating fatigue, palpitations, muscle cramping and weakness. Out of breath and weak after simple tasks like carrying laundry. Many people need to withdraw from Effexor gradually. Abrupt withdrawal as you are doing can cause extreme side effects which can last far longer when you have stopped so suddenly. So in order to consolidate things, I have tried to put together a running list of possible “cures” for heart palpitations that I have found in my research across the internet. Neurasthenia is characterized by general lassitude, irritability, lack of concentration, worry, and hypochondria. Effexor side effects (and this would include other antidepressants as well as Effexor) may cause permanent brain damage. Psychologist Gary Greenberg expressed his concern, citing studies that showed high doses of these drugs cause changes in neurons. I'm so scared and feel like i'm going to die if i try to sleep because of my heart palpitations. I went to the Er yesterday and they attributed my heart to anxiety which is not the case completely.