Some of the withdrawal symptoms associated with abruptly discontinuing use of Effexor XR include dizziness, nightmares, irritability, nausea and headache, according to the National Alliance on Mental Illness. A missed dose may cause a resurgence of original symptoms in some patients.
Nausea, vomiting and a tingling, prickling sensation on the skin, known as paresthesias, are other common symptoms of Effexor XR withdrawal, states the National Alliance on Mental Illness. Withdrawal symptoms may occur within a few hours of reducing the dosage or discontinuing Effexor XR, according to Everyday Health. Fatigue; lack of coordination; electric-like shocks, known as brain zaps; diarrhea; and anxiety are some of the withdrawal symptoms. Since many of Effexor XR's withdrawal symptoms are disorienting, some tasks, such as operating machinery or driving, are dangerous for people experiencing withdrawal from the drug.
As of 2015, trhe manufacturer has discontinued the brand names Effexor and Effexor XR in the United States, but the generic version of the medications, venlafaxine, is available, advises Everyday Health. The FDA black box warnings, side effects and withdrawal symptoms are the same for both the brand name version and the generic version of the medication. The FDA approved Effexor, Effexor XR and venlafaxine for depression, generalized anxiety disorder, panic disorders and social anxiety disorder.