Taking St. John’s Wort and paroxetine may have additive effects and this is because both agents cause additional release of serotonin. And if you get too much, it’s like having your foot on the gas pedal but no foot on the brake. If you get too much, you may get a condition called serotonin syndrome. The symptoms of serotonin syndrome include confusion, fever, hallucinations, nausea, vomiting, shaking, sweating, and possibly even coma, so concurrent use of St. John’s Wort and paroxetine is not recommended unless advised by your medical practitioner who would be monitoring your condition.