A few common side effects of Effexor include drowsiness, nausea, dizziness, and nervousness. Some uncommon Effexor side effects include chest pain, face swelling, and asthma. Among the side effects that you should report to your healthcare provider are hallucinations, fast heart rate, and difficulty breathing. You should also let your healthcare provider know if you experience anything that "just does not seem right" while taking Effexor. He or she will be able to diagnose and treat the problem.
(Click Effexor Side Effects for the full eMedTV article on this topic. This article provides more detailed information about common, rare, and serious side effects that may occur with this drug.)