Venlafaxine Side Effects

Venlafaxine

Venlafaxine Side Effects: Brand Name Effexor. Venlafaxine is available as immediate release 25, 37.5, 50 75 and 100 mg capsules, and as extended release 37.5, 75. 150 and 225 mg capsules. Venlafaxine is one of a class of medications called serotonin/norepinephrine reuptake inhibitors, or SNRIs. These drugs inhibit the post-synaptic reuptake of both serotonin and norepinephrine, two of the neurotransmitter chemicals that are released by one brain nerve ending to stimulate another nerve cell. By inhibiting the reuptake of these chemicals the SNRI’s effectively increase the concentrations of these neurotransmitters in the fluid in the area of the synapse between the brain neurons. Venlafaxine is used for the treatment of depression, anxiety, and panic disorder.

Black Box Warnings: Venlafaxine may increase the risk of suicide, especially when used in adolescents or young adults. Venlafaxine is not approved for use in pediatric medicine, and like many antidepressants needs to be used with care in young adults under 25 years old. See the prescriber’s black box warning form complete details of this black box warning.

Common Venlafaxine Side Effects: Many patients develop annoying venlafaxine side effects including GI side effects like nausea, dry mouth, constipation, vomiting, and loss of appetite. Increased sweating is quite common. Delayed ejaculation and difficulty reaching orgasm in women is very common and is common with essentially all of the SSRI and SNRI medications. Anxiety or nervousness, erectile dysfunction, blurry vision, headache, and trouble sleeping are other common venlafaxine side effects. Excessive yawning, abnormal dreams, and oddly dilated pupils are commonly noted venlafaxine side effects.

Serious Venlafaxine Side Effects: Thoughts of suicide and suicide are the most serious venlafaxine side effects, although an increase in suicide in patients older than 24 years has not been demonstrated in trials, and suicide risk may be reduced in the patients over age 65. Serotonin syndrome is another serious venlafaxine side effect that can be more common due to concomitant use with multiple other drugs. Neuroleptic malignant syndrome is another potentially serious venlafaxine side effect, as is mania, worsening depression, seizures, hypertension, Parkinson’s like symptoms called extrapyramidal symptoms that can include involuntary movements of the face and mouth, hyponatremia and SIADH, cardiac arrhythmias, abnormal platelet function and risk of bleeding, pancreatitis, various allergic reactions and skin reactions, and growth retardation with use in children. For a more complete discussion of serious and common venlafaxine side effects see the manufacturer’s prescribing guidelines.

Venlafaxine Drug Interactions: Venlafaxine is contraindicated for use with cisapride (not available in the US), dronedarone (Trade name Multaq, used as an antiarrythmic for treatment of atrial fibrillation), all of the non-selective Monoamine Oxidase Inhibitors (MAO inhibitors), and with the phenothiazines (examples include prochlorperazine trade name Compazine, chlorpromazine, thioridazine, Stelazine, and Robinul). Venlafaxine should be avoided or used very cautiously in conjunction with any of the SSRI medications because of an increased risk of the “serotonin syndrome.” This is overstimulation of the central nervous system by serotonin which can cause symptoms of sweating, confusion, increased temperature, cardiac palpitations and arrhythmias and can be very serious and life-threatening. The list of potential drug interactions is extensive and you should refer to the manufacturer’s prescribing information for a complete list of potential drug interactions.

Venlafaxine use in Pregnancy and Lactation: Pregnancy Category C. Lactation safety is currently unknown.

Abrupt Discontinuation Syndrome: Venlafaxine is a short half-life medication (approximately 5 hours average half-life) and so with discontinuation is fairly quickly cleared from the user’s body largely unchanged in the urine. Abrupt discontinuation of venlafaxine typically leads to a discontinuation syndrome and so the medication best stopped by a slow taper off the medication. The manufacturer recommendation is to reduce the dose gradually over 2 weeks or more to discontinue, especially if taking doses of 75 mg or more. Effexor Withdrawal Side Effects can be quite annoying with symptoms of confusion, dizziness and vertigo, electrical shock like symptoms and other bothersome withdrawal symptoms.

Special Considerations: Venlafaxine can unmask the mania of undiagnosed bipolar disorder, and if increased anger, agitation, or other symptoms of mania occur patients using venlaxfaxine should immediately seek medical attention.

Unusual Venlafaxine Side Effects: The sexual dysfuntion with delayed ejaculation and orgasmic dysfunction in women is unique to the SSRI and SNRI classes of medications. Yawning and sweating are somewhat unusual venlafaxine side effects.