Medicines of any class or description are believed to cause some sort of side effects in some typical patient due to their individual health conditions. As revealed by the manufacturer of Effexor-Venlafaxine Wyeth Pharmaceuticals Inc., may cause some side effects such as: nausea, headache, lethargy, constipation, persistent irritable bowel disorder, dizziness, exhaustion, sleeplessness or insomnia, vertigo, dry mouth, sexual dysfunction, excessive sweating, Hallucination or dreams, impulsive actions, raised blood pressure, loss or reduced appetite, brain zaps or electric shock-like feelings, enhanced anxiety at the beginning of the treatment, agitation and loss of memory.

Besides all these, in some patients even some rare side effects may also be experienced such as: cardiac arrhythmia, raised serum cholesterol levels, gas or stomach pain, abnormal vision quality, nervousness, agitation or hyper anxiety, panic attacks, feeling depressed, developing suicidal thoughts, confusion, neuroleptic malignant disorder, loss of appetite, shiver, drowsiness, allergic skin reactions, external bleeding, serious bone marrow damage or thrombocytopenia or agranulacytosis, hepatitis, pancreatitis, seizures, tardive dyskinesias, difficulty in swallowing, psychosis, hair loss, hostility, hypomania or development of mania.

More over effects like weight loss which is rather alarming especially while treating the patient suffering from anorexia nervosa, weight gain especially when the patient having body dysmorphic disorder being treated with this medication, homicidal thoughts, antagonism or aggression, depersonalization, visual hallucinations, unexpected swelling or bleeding in the gums and recurrent need of passing urine. Besides these, certain adverse effects may also be reported by the patients that include: lack of sexual desire or delayed ejaculation and delayed orgasm especially in male patients.