Studies suggest that valerian is generally safe to use for short periods of time (for example, 4 to 6 weeks).
No information is available about the long-term safety of valerian.
Valerian can cause mild side effects, such as tiredness the morning after its use, headaches, dizziness, and upset stomach.
Tell all your health care providers about any complementary health practices you use. Give them a full picture of what you do to manage your health. This will help ensure coordinated and safe care. For tips about talking with your health care providers about complementary and alternative medicine, see NCCAM's Time to Talk campaign.