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http://effexorxr.com/faqs.asp#10

What happens when I stop using EFFEXOR XR?
Symptoms are known to occur when people stop using EFFEXOR XR, especially when they suddenly stop therapy.

When people suddenly stop using EFFEXOR XR, they can get symptoms from stopping the medicine too fast. Some of these symptoms include:

Agitation Anxiety Confusion Diarrhea Dizziness or vertigo Dry mouth Fasciculation (muscle twitching) Headaches Hypomania Impaired coordination Insomnia (trouble sleeping) Loss of appetite Nausea

Nervousness Nightmares Seizures Sensory disturbances (including electric shock sensations) Somnolence (sleepiness) Sweating Tinnitus Tiredness Tremor Unpleasant mood Vomiting

Do not stop taking EFFEXOR XR without talking with your doctor first. Your doctor may want to slowly decrease your dose of EFFEXOR XR to help avoid these kinds of symptoms.