If Effexor (venlafaxine) treats anxiety disorders, why is nervousness a common side-effect?

Anxiety modulation. Some antidepressants modulate ; treat anxiety ; are the backbone treatment of anxiety. All can increase anxiety levels if not started at very small dosages ; titrated slowly ; carefully by the treating physician. We use them with good results in our center, but not all types of anxiety respond to it well. Some respond better to other meds i.e. Citalopram or fluvoxamine. Good luck ; feel better.
Medication effects. Thank you for informing about myelogenous leukemia and taking Effexor, Sprycel, and Flomax. I feel empathy for what you have gone through. All 3 medications can have side effect of Effexor, Sprycel, and Flomax. Please see your Physician about • Benefits and side effects of these medications • Medication interactions • T0 decrease dose of Effexor • Discuss Ativan or Xanax for Anxiety.
Body chemistry. First, Effexor (venlafaxine) is primarily an antidepressant and, in my experience, only occasionally reduces anxiety. Ever body is different and a few people develop nervousness from the drug, but that's unusual. Remember, some people develop side effects from peanuts or chocolate. Some get agitated after drinking coffee. Every person's body chemistry is unique.