http://www.ncbi.nlm.nih.gov/pubmedhealth/PMH0000947/
Reference
Side Effects;
What side effects can this medication cause?
Venlafaxine may cause side effects. Call your doctor if any of the following symptoms are severe or do not go away:
drowsiness
weakness or tiredness
dizziness
headache
nightmares
nausea
vomiting
stomach pain
constipation
diarrhea
gas
heartburn
burping
dry mouth
change in ability to taste food
loss of appetite
weight loss
uncontrollable shaking of a part of the body
pain, burning, numbness, or tingling in part of the body
muscle tightness
twitching
yawning
sweating
hot flashes or flushing
frequent urination
difficulty urinating
sore throat, chills, or other signs of infection
ringing in the ears
changes in sexual desire or ability
enlarged pupils (black circles in the middle of the eyes)
Some side effects can be serious. If you experience any of the following symptoms or those listed in the IMPORTANT WARNING section, call your doctor immediately:
rash
hives
itching
difficulty breathing or swallowing
chest pain
fast, pounding, or irregular heartbeat
seizures
unusual bruising or bleeding
small purple spots on the skin
eye pain or redness
changes in vision
fever, sweating, confusion, fast or irregular heartbeat, and severe muscle stiffness
fever
problems with coordination
hallucinations (seeing things or hearing voices that do not exist)
coma (loss of consciousness for a period of time)