Research suggests that valerian does not impair one’s ability to drive or operate machinery.⁸ There is one case reported of a man experiencing severe cardiac symptoms that may have been due to withdrawing from valerian. This man abruptly discontinued taking valerian, after having used 5–20 times the recommended amount “for many years”.⁹ However, when taken at recommended amounts, valerian supplementation does not lead to addiction or dependence. In the case of an 18-year old college student who tried to kill herself by ingesting approximately 20,000 mg of valerian root (approximately 40–50 times the recommended amount), the only symptoms reported were fatigue, abdominal pain, and a mild tremor of the hands and feet.¹⁰ Valerian does not appear to impair reaction time, alertness, or concentration the morning after use.¹¹ There are no known reasons to avoid valerian during pregnancy or breast-feeding.