toxicity and interactions

Last reviewed 01/2018

• included in the pooled clinical trial database of 3,082 patients treated with venlafaxine were 14 patients who had taken an overdose of venlafaxine - all 14 patients survived the overdose and recovered without sequelae. One patient ingested 2.75 grams of venlafaxine and did suffer two epileptiform convulsions and developed a prolonged QT interval
  
  
• monoamine oxidase inhibitors are contraindicated with venlafaxine - it is advised that there is a 14-day washout period between stopping an MAOI and starting venlafaxine treatment. The 'Serotonin syndrome' may occur as a result of inadvertent consumption of venlafaxine and an MAOI
  
  
• during clinical trials, discontinuation phenomena from venlafaxine were reported with abrupt discontinuation after daily doses of 150 mg per day or higher - these usually occurred within 2 days of significant dose reduction and generally resolved within 7 days of stopping treatment. The commonly reported phenomena were headache, nausea and dizziness (1)

Reference:

• Prescribers' Journal (1999), 39 (4), 243-247.