Venlafaxine is a serotonin-norepinephrine reuptake inhibitor (SNRI) antidepressant that has been widely prescribed since the 1990s. It is considered one of the most effective and versatile agents for the treatment of major depressive disorder (MDD), generalized anxiety disorder (GAD), social anxiety disorder, and panic disorder. Unlike selective serotonin reuptake inhibitors (SSRIs), which primarily act on serotonin reuptake, venlafaxine exerts dose-dependent effects: at lower doses, it acts predominantly as a serotonin reuptake inhibitor; at moderate doses, it blocks both serotonin and norepinephrine reuptake; and at higher doses, it can also modestly inhibit dopamine reuptake. This multi-faceted pharmacological profile provides broader coverage for treatment-resistant depression and anxiety disorders.
The drug is available in immediate-release (IR) and extended-release (XR) formulations. The XR formulation is preferred in most cases due to improved tolerability, once-daily dosing, and reduced risk of gastrointestinal side effects. Venlafaxine is metabolized hepatically by CYP2D6 into its active metabolite, O-desmethylvenlafaxine (ODV), which contributes significantly to its antidepressant efficacy. Genetic polymorphisms in CYP2D6 can influence drug levels, efficacy, and risk of side effects.
Venlafaxine is valued for its robust efficacy but is also recognized for its discontinuation syndrome, which can occur when doses are missed or the drug is stopped abruptly. Symptoms may include dizziness, headache, nausea, irritability, “electric shock” sensations, and sleep disturbance. This requires clinicians to taper the drug carefully when discontinuing or switching therapy. Despite this challenge, venlafaxine remains a cornerstone in modern psychopharmacology due to its high effectiveness across multiple psychiatric indications.
Patients should be counselled on the importance of not stopping the drug suddenly and to follow clinician instructions closely if transitioning to another antidepressant.
Most side effects improve with continued use, but patients should promptly report any concerning symptoms to their healthcare provider.
Patients should be advised to adhere to follow-up appointments for blood pressure checks and mental health monitoring.
Venlafaxine is metabolized primarily by CYP2D6 and to a lesser extent by CYP3A4. It has significant interactions with serotonergic and cardiovascular agents:
Patients must inform their clinician about all medications and supplements, including herbal and over-the-counter products, before starting venlafaxine.
Overdose: Can be life-threatening. Symptoms include severe dizziness, vomiting, rapid heart rate, seizures, cardiac arrhythmias, hypertension or hypotension, and coma. Supportive management includes airway protection, activated charcoal if early, monitoring of cardiac rhythm, and intensive care if needed. There is no specific antidote.
Accidental double dose: May cause transient nausea, dizziness, or mild blood pressure increase. Monitor and seek advice if symptoms worsen.
Missed dose: Take as soon as remembered unless close to the next scheduled dose. If near the next dose, skip the missed one—do not double up. For XR formulations, try to take consistently at the same time daily to avoid withdrawal symptoms.
Patients should be warned that withdrawal can occur even after missing a single XR dose, and adherence is therefore crucial.
The information provided on this website is for general educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your doctor, pharmacist, or other qualified health provider with any questions you may have regarding a medical condition or medication. Do not disregard professional medical advice or delay seeking it because of something you have read here. We do not take responsibility for any loss, damage, or injury caused by this information.