Types of Side Effects

• The most common side effects of venlafaxine HCL include weakness, sweating, nausea, constipation, loss of appetite, drowsiness, vomiting, dry mouth, anxiety, tremors and blurred vision.
  
  

Significance

• The most common side effects of venlafaxine HCL occur in 5 to 25 percent of users, according to FDA clinical trials published on RxList.
  
  

Drug Interactions

• When taken with blood thinning drugs like warfarin, venlafaxine HCL has the potential to cause sudden and severe bleeding. The combination of venlafaxine HCL and an MAO inhibitor antibiotic poses a risk of hyperthermia and seizures, which can be fatal in some cases.
  
  

Risks

• During the first few months of treatment, venlafaxine HCL poses a risk of suicidal thoughts or self-harmful behavior, warns RxList. Other risks associated with venlafaxine HCL include serotonin syndrome and hypertension.
  
  

Considerations

• Because its effects upon fetal development are unknown, doctors rarely prescribe venlafaxine HCL for use in pregnant women. If you have a history of bipolar disorder, bleeding problems, glaucoma, seizures, hypertension, high cholesterol, low levels of blood sodium, heart attacks, congestive heart failure, mania or kidney or liver disease, it may not be safe for you to take venlafaxine HCL due to its potential side effects, warns the Mayo Clinic.