Is it safe to take valerian root pill if i already take effexor (venlafaxine)?

Yes: Typically there is no problem with valerian root and other medications, namely antidepressants. In general Effexor (venlafaxine) is very stimulating. If having trouble calming in evening and taking this pill at night, consider change Effexor (venlafaxine) to am after speaking with doctor. In people with sleep disturbances, even if due to anxiety, taking Effexor (venlafaxine) at night can cause insomnia.

Effexor (venlafaxine) + Valerian: This is controversial, since valerian is sedating and can add to this aspect in many antidepressants. I've had patients who found Effexor (venlafaxine) sedating, especially at doses below 150mg (where it inhibits ne reuptake, not just serotonin like at lower doses). So depending on your experience with Effexor (venlafaxine) i'd be careful and work with my doctor. There aren't any specific interactions between these 2.