Venlafaxine — Antidepressant Medication Guide | KiwiMeds
✅ Reviewed by a Registered Pharmacist NZ | Last updated: May 2026 | This information is for educational purposes only and does not replace advice from your doctor or pharmacist.
What is venlafaxine?
Venlafaxine is an antidepressant belonging to the SNRI (serotonin-norepinephrine reuptake inhibitor) class. It is used to treat depression, generalised anxiety disorder, and panic disorder. Brand names in NZ include Efexor-XR and various generics.
What is it used for? (NZ context)
Venlafaxine is prescribed for major depression, generalised anxiety disorder (GAD), social anxiety disorder, and panic disorder. It may be used when SSRIs (such as sertraline or fluoxetine) have not worked sufficiently. Pharmac funds venlafaxine extended-release capsules.
How does it work?
Venlafaxine blocks the reuptake of both serotonin and norepinephrine, increasing the availability of these neurotransmitters in the brain. At lower doses it mainly affects serotonin; at higher doses, norepinephrine is also affected. This dual action can be helpful for people who do not respond to SSRIs alone.
How to take it
Venlafaxine extended-release (XR) capsules are taken once daily with food. Do not crush or chew extended-release capsules. Antidepressants take 2–4 weeks to show benefit. Do not stop suddenly — this can cause discontinuation syndrome (dizziness, nausea, “electric shock” feelings). Always taper slowly under medical supervision.
Common side effects
- Nausea — common especially when starting
- Increased sweating
- Dry mouth
- Headache
- Insomnia or drowsiness
- Increased blood pressure (at higher doses)
Serious side effects to watch for
Venlafaxine can increase blood pressure, particularly at higher doses — your doctor will monitor this. Like all antidepressants, there is a small increased risk of suicidal thoughts in young people under 25 at treatment start — monitor closely. Serotonin syndrome is rare but serious.
Important drug interactions
MAOIs — never combine with venlafaxine; allow 14 days between stopping an MAOI and starting venlafaxine. Tramadol and other serotonergic medicines increase serotonin syndrome risk. Blood thinners (warfarin) — venlafaxine may increase bleeding risk. NSAIDs and aspirin — increased risk of bleeding.
NZ-specific information
Pharmac funding: Venlafaxine extended-release capsules (75mg, 150mg) are funded by Pharmac. The original brand Efexor-XR and generic venlafaxine XR are both available. Immediate-release tablets are less common in NZ.
Frequently asked questions
Why do I feel worse when I miss a dose of venlafaxine?
Venlafaxine has a short half-life. Missing doses can cause discontinuation symptoms including dizziness, nausea, irritability, and “brain zaps” (electric shock sensations in the head). Take it at the same time each day to avoid this.
Can I drink alcohol on venlafaxine?
Alcohol and venlafaxine both affect the brain, and combining them can worsen depression and increase side effects like dizziness and sedation. It is safest to avoid or minimise alcohol while taking antidepressants.
How long will I need to take venlafaxine?
Most people are advised to continue antidepressants for at least 6–12 months after feeling well to reduce the risk of relapse. Some people take it longer-term. Always discuss stopping with your doctor.
💬 Talk to your pharmacist or doctor for personalised advice about venlafaxine.
Reviewed by a Registered Pharmacist NZ | BPharm, Pharmacy Council of New Zealand
References & Further Information
The following New Zealand and international resources were used to inform this page: