St John’s Wort (Hypericum perforatum) is a poisonous plant commonly employed as an herbal remedy for treating depression. The plant’s golden-yellow flowers bloom abundantly in July and August throughout the Northern Hemisphere.

St John’s Wort leaves are frequently ingested to curb depression. However, in combination with other antidepressants like Prozac or Zoloft, a build up of serotonin occurs. Symptoms of excess serotonin include queasiness, anxiety, confusion, vertigo and unmanageable muscle twitching. Excess exposure to this plant can also cause skin irritation and sensitivity to sunlight.