Valerian is LIKELY SAFE for most people when used in medicinal amounts short-term. Clinical studies have reported safe use of valerian for medicinal purposes in over 12,000 people in trials lasting up to 28 days. The safety of long-term use is unknown. Some information suggests that valerian might also be safe when taken by children for 4-8 weeks.
Valerian can cause some side effects such as headache, excitability, uneasiness, and even insomnia in some people. A few people feel sluggish in the morning after taking valerian, especially at higher doses. It’s best not to drive or operate dangerous machinery after taking valerian. The long-term safety of valerian is unknown. To avoid possible side effects when discontinuing valerian after long-term use, it's best to reduce the dose slowly over a week or two before stopping completely.