Scottsdale, Arizona - Several herbal remedies have been studied as a treatment for anxiety, but more research is needed to understand the risks and benefits. Here's what we know and don't know:

• Kava. Kava appeared to be a promising treatment for anxiety, but reports of serious liver damage — even with short-term use — caused the Food and Drug Administration to issue warnings about the use of dietary supplements containing kava. While these initial reports of liver toxicity have been questioned, use extra caution and involve your doctor in the decision if you're considering using products containing kava.
• Passion flower. A few small clinical trials suggest that passion flower might help with anxiety. In many commercial products, passion flower is combined with other herbs, making it difficult to distinguish the unique qualities of each herb. Passion flower is generally considered safe when taken as directed, but some studies found it can cause drowsiness, dizziness and confusion.
• Valerian. In some studies, people who used valerian reported less anxiety and stress. In other studies, people reported no benefit. Valerian is generally considered safe at recommended doses, but since long-term safety trials are lacking, don't take it for more than a few weeks at a time, unless your doctor approves. It can cause some side effects such as headaches, dizziness and drowsiness.
• Chamomile. Limited data shows that short-term use of chamomile is generally considered safe and can be effective in reducing symptoms of anxiety. But chamomile can increase the risk of bleeding when used with blood-thinning drugs. Use of chamomile can cause allergic reactions in some people who are sensitive to the family of plants that includes chamomile. Other members of this family are ragweed, marigolds, daisies and chrysanthemums.
• Lavender. Some evidence suggests that oral lavender or aromatherapy with lavender can reduce anxiety; however, evidence is preliminary and limited. Oral lavender can cause constipation and headaches. It can also increase appetite, increase the sedative effect of other medications and supplements, and cause low blood pressure.
• Lemon balm. Preliminary research shows lemon balm can reduce some symptoms of anxiety, such as nervousness and excitability. Lemon balm is generally well-tolerated and considered safe for short-term use, but can cause nausea and abdominal pain.

Herbal supplements aren't monitored by the FDA the same way medications are. Despite enhanced quality control regulations in place since 2010, the quality of some supplements may still be an issue. Remember, natural doesn't always mean safe.

If you're considering taking any herbal supplement as a treatment for anxiety, talk to your doctor first, especially if you take other medications. The interaction of some herbal supplements and certain medications can cause serious side effects.

Some herbal supplements taken for anxiety can cause you to feel sleepy, so they may not be safe to take when driving or doing dangerous tasks. Your doctor can help you understand possible risks and benefits if you choose to try an herbal supplement.

If your anxiety is interfering with daily activities, talk with your doctor. More-serious forms of anxiety generally need medical treatment or psychological counseling (psychotherapy) for symptoms to improve.

This article is written by Brent A. Bauer, M.D., director of Mayo Clinic's Complementary and Integrative Medicine Program.