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PRISTIQ® (desvenlafaxine)

Switching patients between Pristiq® and other antidepressants

Discontinuation symptoms have been reported when switching patients from other antidepressants, including venlafaxine to desvenlafaxine. Tapering of the initial antidepressant followed by a washout period may be necessary to minimise discontinuation symptoms and the possibility of drug-drug interactions from a pharmacokinetic or pharmacodynamic perspective.1

Pfizer does not have any specific recommendations with regards to switching patients between antidepressants, including to/from Pristiq.1

You may wish to refer to tertiary references to assist in your clinical decision. For your reference, an antidepressant changeover guide from the Australian Medicines Handbook2 has been provided below.

Antidepressant Changeover Guide2

© Australian Medicines Handbook 2018

Category A changeover
fluoxetine, phenelzine, tranylcypromine, vortioxetine
  • gradual withdrawal generally unnecessary; withdrawal symptoms very unlikely
  • wait for at least 14 days before starting next antidepressant (may be up to 5 weeks with fluoxetine)
  • consider hospitalisation during washout/changeover if severely depressed
drug (or metabolites) with long half-life or persistent effects
Category B changeover
TCAs, SSRIs (except fluoxetine), mianserin, mirtazapine
  • withdraw gradually to prevent withdrawal symptoms (particularly if higher dose or long-term use); usually reduce dose by 25% per day
  • wait for 2-4 days before starting next antidepressant
  • consider hospitalisation during washout/changeover if severely depressed
  • mianserin: withdrawal symptoms rare
drug (or metabolites) with intermediate half-life of 24-48 hours
Category C changeover
agomelatine, moclobemide, reboxetine, SNRIs
  • SNRIs: withdraw gradually to prevent withdrawal symptoms
  • agomelatine, moclobemide, reboxetine: withdrawal symptoms not reported or rare
  • wait for 1-2 days before starting next antidepressant (agomelatine can be started immediately if switching from an SSRI to SNRI)
drug (or metabolites) with short half-life of <18 hours
# consider any interaction between the drug being stopped and the new drug; this may affect the changeover period
* interval before starting next antidepressant may differ from that recommended by other sources, eg product information


  1. Pristiq®(desvenlafaxine) Product Information
  2. Antidepressant changeover guide (last modified Jul 2018). Australian Medicines Handbook 2018 [online]. Adelaide: Australian Medicines Handbook Pty Ltd; 2018 July. Available from:

Use of Pristiq® during pregnancy & lactation

Pregnancy Category B2; the safety of Pristiq in human pregnancy has not been established. Only administer Pristiq to pregnant women if the expected benefits outweigh any possible risk. If Pristiq is used until, or shortly before birth, discontinuation effects in the newborn should be considered.

Desvenlafaxine (O-desmethylvenlafaxine) is excreted in human milk. Because of the potential for serious adverse reactions in nursing infants from desvenlafaxine, a decision should be made whether or not to discontinue nursing or to discontinue the drug, taking into account the importance of the drug to the mother. Only administer Pristiq to breastfeeding women if the expected benefits outweigh any possible risk.


Pristiq®(desvenlafaxine) Product Information

Presence of Pristiq® tablet in the stool

Patients receiving Pristiq may notice an inert matrix tablet passing in the stool or via colostomy. Patients should be informed that the active medication has already been absorbed by the time the patient sees the inert matrix tablet.


Pristiq®(desvenlafaxine) Product Information

Halving or crushing Pristiq® tablets

Pristiq is formulated as an extended-release tablet for once-a-day oral administration. Tablets must be swallowed whole with fluid and not divided, crushed, chewed or dissolved.

Due to the complex nature of the carefully controlled release of active drug from the tablet, splitting, crushing, or placing the tablet in solution alters the exposed surface area of the tablet and disrupts the extended release mechanism. Active drug is physically constrained in a rate-controlling polymer (hypromellose) and the tablet surface area/tablet volume ratio must not be disrupted to prevent alteration of the release-rate of active drug. Any type of physical alteration to the tablet may result in various types of untoward responses including erratic absorption of dose, failure to achieve adequate plasma concentrations and a rapid release of excessive amount of drug that may result in acute precipitation of adverse effects.


1. Pristiq®(desvenlafaxine) Product Information

2. Data on file (115). Pfizer.

3. Data on file (162). Pfizer.

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