Based on animal and human studies, valerian may increase the amount of drowsiness caused by some drugs, although this is an area of controversy. Examples include benzodiazepines such as lorazepam (Ativan®) or diazepam (Valium®), barbiturates such as phenobarbital, narcotics such as codeine, some antidepressants, and alcohol. Caution is advised while driving or operating machinery. In one human study, a combination of valerian and the beta-blocker drug propranolol (Inderal®) reduced concentration levels more than valerian alone. A brief episode of confusion was reported in one patient using valerian with loperamide (Imodium®) and St. John's wort (Hypericum perforatum L.).
An episode of agitation, anxiety, and self-injury was reported in a patient after taking valerian with fluoxetine (Prozac®) for a mood disorder (the person was also drinking alcohol). In theory, valerian may interact with anti-seizure medications, although human data is lacking. Valerian tinctures may contain high alcohol content (15-90%) and theoretically may cause vomiting if taken with metronidazole (Flagyl®) or disulfiram (Antabuse®). Valerian may interact with certain drugs metabolized by the liver or vasopressin.
Based on theoretical concerns, valerian may increase the amount of drowsiness caused by some herbs or supplements.
A brief episode of confusion was reported in one patient during use of valerian with loperamide (Imodium®) and St. John's wort (Hypericum perforatum L.). Nausea, sweating, muscle cramping, weakness, elevated pulse, and high blood pressure were reported after a single dose of a combination product with St. John's wort, kava, and valerian. Valerian may interact with certain herbs and supplements that are metabolized by the liver.
This information is based on a professional level monograph edited and peer-reviewed by contributors to the Natural Standard Research Collaboration (www.naturalstandard.com): Ethan Basch, MD (Memorial Sloan-Kettering Cancer Center); Samuel Basch, MD (Mt. Sinai Medical Center); Steven Bratman, MD; Cathi Dennehy, PharmD (University of California, San Francisco); Dawn Costa, BA, BS (Natural Standard Research Collaboration); Gerald Gianutsos, PhD (University of Connecticut School of Pharmacy); Taras Hollyer, BSc, MSc (Canadian College of Naturopathic Medicine); Charles Holmes, MD (Harvard Medical School); Adrianne Rogers, MD (Boston University Medical Center); Shaina Tanguay-Colucci, BS (Natural Standard Research Collaboration); Catherine Ulbricht, PharmD (Massachusetts General Hospital); Mamta Vora, PharmD (Northeastern University); Wendy Weissner, BA (Natural Standard Research Collaboration).
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Remember, keep this and all other medicines out of the reach of children, never share your medicines with others, and use this medication only for the indication prescribed.