Effexor XR (Venlafaxine)

  • Generic name: Venlafaxine hydrochloride
  • Brand names: Effexor, Effexor XR (Extended Release); Efexor (AU, UK)
  • Pharmacologic class: Antidepressant, Serotonin and norepinephrine reuptake inhibitor (SNRI)

What is Effexor used for?

  • Depression, including retarded depression, atypical depression, comorbid anxiety, and depression not responding to SSRIs.
  • Generalised anxiety disorder
  • Social anxiety disorder
  • Obsessive compulsive disorde
  • Panic disorder
  • Fibromyalgia
  • Hot flashes in menopause

How long it takes for Effexor to work?

Venlafaxine has quick onset of effect and may work faster than Wellbutrin, Celexa, Cymbalta, or Prozac. But it may take several weeks before you begin to feel better.

If it is not working within 6-8 weeks for depression, it may require a dosage increase or it may not work at all. However for anxiety, improvements may still occur after 8 weeks, and for up to 6 months after initial dose.

Once symptoms are gone and remission is achieved, you may continue taking Effexor for up to 1 year to escape from future relapses of depression.


Venlafaxine should NOT be used:

  • In combination with MAO inhibitors or within two weeks of discontinuing MAO inhibitor. Concomitant use with MAO inhibitors may result in serious, sometimes fatal reactions.
  • In people with uncontrolled hypertension, high risk of serious cardiac arrhythmias, or recent myocardial infarction. Venlafaxine may cause sustained increase in blood pressure or tachycardia. Blood pressure should be checked on initiation and regularly during treatment. If there is a sustained increase in blood pressure consider dose reduction or discontinuation. People with pre-existing hypertension may only be prescribed venlafaxine if their blood pressure is controlled.

Venlafaxine is not appropriate for those who are sensitive to nausea.

Drug interactions

Venlafaxine is metabolized by CYP isoenzymes, principally by CYP2D6 and CYP3A4.

  • MAO inhibitors: concomitant use contraindicated, potentially fatal serotonin syndrome
  • Serotonergic agent (e.g. triptans, sibutramine, tramadol, SSRIs, SNRIs): possible serotonin syndrome, use with caution
  • Tryptophan and other serotonin precursors: possible serotonin syndrome, concomitant use not recommended
  • Lithium: potentially additive serotonergic effects, caution advised
  • Diazepam: no significant interactions between t venlafaxine and diazepam

Venlafaxine in combination with other medications

Mirtazapine (Remeron): The combination of venlafaxine with mirtazapine (sometimes referred to as “California rocket fuel”) is used to treat refractory depression3. The principal benefit of this combo is to limit effects of increased serotonergic activity, allowing venlafaxine to be titrated faster and to be better tolerated.

Bupropion (Wellbutrin): Addition of bupropion to venlafaxine may work for resistant depression and may help to reverse sexual dysfunction4. Bupropion increases venlafaxine levels, but there is a concurrent decrease of desvenlafaxine (its active metabolite) levels.

Trazodone: Sometimes, trazodone is added to other antidepressants to treat insomnia2. However, the combination can produce severe serotonin syndrome and liver toxicity.

Warning! The combination of venlafaxine with multiple drugs affecting serotonin may be fatal.


  • 1. Effexor XR capsules prescribing information. PDR. 59th Edition. Montvale, NJ: Thomson PDR, 2005, p. 3326-3333.
  • 2. Bertschy G, Ragama-Pardos E, Muscionico M, Aït-Ameur A, Roth L, Osiek C, Ferrero F. Trazodone addition for insomnia in venlafaxine-treated, depressed inpatients. Pharmacol Res. 2005 Jan;51(1):79-84.
  • 3. Malhi GS, Ng F, Berk M. Combining venlafaxine and mirtazapine in the treatment of depression. Aust N Z J Psychiatry. 2008 Apr;42(4):346-9. PubMed
  • 4. DeBattista C, Solvason HB, Poirier J, Kendrick E, Schatzberg AF. J Clin Psychopharmacol. 2003 Feb;23(1):27-30.
  • 5. Polen KN, Rasmussen SA, Riehle-Colarusso T, Reefhuis J; National Birth Defects Prevention Study. Association between reported venlafaxine use in early pregnancy and birth defects, national birth defects prevention study, 1997-2007. Birth Defects Res A Clin Mol Teratol. 2013 Jan. PubMed
  • 6. Newport DJ, Ritchie JC, Knight BT et al. Venlafaxine in human breast milk and nursing infant plasma: determination of exposure. J Clin Psychiatry. 2009;70:1304-10. PubMed

Last updated: February, 2015

Advanced Consumer Info

effexor xr
venlafaxine 37.5 mg

  • Pregnancy Category: C. Recent 2013 study found statistically significant associations between venlafaxine use in early pregnancy and coarctation of the aorta, and several other serious birth defects5.
  • Breastfeeding: The rate of venlafaxine/desvenlafaxine excretion into human breast milk is relatively high6.
  • Elimination half-life: 5 hours for venlafaxine and 10 hours for its primary metabolite O-desmethylvenlafaxine.
  • Mechanism of action: Venlafaxine block both serotonin and norepinephrine reuptake.
  • Effexor has a good remission rate for depression that resisted other antidepressants.
  • The newest SNRI similar to venlafaxine is Pristiq (desvenlafaxine).