Hello, thanks for using HCM. The active substance of pristiq is desvenlafaxine which belongs to a group of antidepressants called selective serotonine and norepinephrine re-uptke inhibitors. The drug blocks movement of serotonin across synapses in the nervous system leaving more active neurotransmitters in the synapse. Side effects of desvenlafaxine include dizziness, anxiety, nausea, dry mouth, constipation, loss of appetite, weight loss, blurred vision, trouble sleeping, drowsiness, increased blood pressure, abnormal bleeding and increased cholesterol. Your symptoms could well be explained by intake of pristiq. I will advise you see your physician for a thorough evaluation and to rule out the possibility other pathologies before concluding on pristiq intake. thanks.