Overdose Information for Effexor Revised

Overdosing on Effexor (venlafaxine) may put patients at greater risk for death compared with overdosing on SSRIs, according to newly revised prescribing information for the drug.

Patients on venlafaxine also have more pre-existing suicide risk factors than those on SSRIs, according to the new label; it is unclear how much of the increased risk of death is due to the toxicity of venlafaxine and how much is due to characteristics of patients who take the drug.

In post-marketing surveillance, venlafaxine overdoses occurred mainly in combination with alcohol and other drugs. The most common events in venlafaxine overdose were tachycardia, reduced consciousness, mydriasis, and seizures. Other reported events include hypotension, liver necrosis, rhabdomyolysis, serotonin syndrome, and electrocardiogram changes, such as QT prolongation and QRS prolongation.

Physicians are advised to reduce the risk for overdose by writing venlafaxine prescriptions for the smallest quantity consistent with good patient management.