Open Source Apothecary At Home / Mind and sleep

Anxiety: kava, lavender and the herbs with trials

Kava has the best trial evidence of any herb for anxiety, and it is the one with a liver warning attached.

remedy

Anxiety responds to non-drug treatment well — cognitive behavioural therapy and exercise both have randomised evidence comparable to medication for mild to moderate anxiety — and that is where the strongest recommendation on this page sits. The herbs are a step below that.

Kava (Piper methysticum) has the best randomised trial evidence of any herb for anxiety, with pooled analyses showing a significant reduction in anxiety symptoms over placebo. It also has a hepatotoxicity caution: a number of cases of liver injury, including severe ones, led to restrictions in several countries. The mechanism is not established and it appears to be idiosyncratic rather than dose-dependent, meaning that a normal dose is not a reassurance. The practical position: use only a properly prepared root extract from a reputable supplier with a documented quality history, avoid it with alcohol and with any other potentially hepatotoxic drug, avoid it if there is any liver disease, and discuss it with a clinician given that the evidence is genuinely positive and the safety signal is genuine. Do not use it long-term without review.

Lavender oil, orally as a standardised capsule (Silexan), has randomised trials showing anxiolytic effect comparable to a low-dose benzodiazepine in some studies, without sedation or dependence. This is a genuinely interesting finding and it is a specific licensed preparation, not the same thing as a diffuser or a bath oil. Inhaled lavender is a pleasant adjunct with weaker evidence.

Passionflower has small trials showing anxiolytic effects and a perioperative anxiety trial; it is gentle and well tolerated.

Ashwagandha has small trials showing reduced stress and cortisol measures. The trials are short, and there are case reports of liver injury, so it is not a free pass.

Adaptogens, generally. The term is a marketing category rather than a pharmacological one, and the trials behind the individual plants are mostly small and short. That does not make them useless; it means that the pooled evidence for "adaptogens" as a class is weaker than the marketing for any individual product suggests.

The caution that matters most in this section. Herbal sedatives and anxiolytics add to alcohol, benzodiazepines, opioids and other sedatives. And someone who is anxious with panic attacks, or with suicidal thoughts, needs clinical care rather than a supplement — anxiety is very treatable and a supplement trial is not a plan.

What the studies found

Preparation

Kava

• Standardised root extract, as used in the trials (commonly 120-250 mg of kavalactones daily, divided)
• Use a reputable supplier with a quality record. Traditional aqueous preparations and good-quality root are lower risk than leaf/stem material and solvent extracts.
• Avoid with alcohol. Cases of liver injury have concentrated where alcohol was involved.
• Avoid in liver disease, and avoid combining with other potentially hepatotoxic drugs.
• Do not use long-term without review. Stop if jaundice, dark urine or fatigue develops.

Lavender, oral capsule

• The licensed standardised preparation (Silexan) used in the trials: 80 mg daily
• This is not interchangeable with a dropper of essential oil. Never swallow essential oil.
• Inhaled lavender, a few drops on a tissue or in a diffuser, is a pleasant adjunct with weaker evidence

Passionflower

• 1-2 g dried herb as an infusion, 2-3 times daily, or a standardised extract
• Gentle; can add to sedation

Ashwagandha

• 300-600 mg of a standardised root extract daily in the trials
• Short courses; case reports of liver injury exist
• Not in pregnancy

The interventions with the strongest evidence

• Cognitive behavioural therapy, which has randomised evidence in anxiety disorders
• Exercise — regular aerobic activity has randomised evidence for anxiety
• Reducing caffeine and alcohol, both of which worsen anxiety
• Sleep — the relationship between sleep and anxiety runs both ways
• Breathing and relaxation training: slow breathing at about 6 breaths per minute has measurable effects on autonomic measures

When a supplement is not the plan

• Panic attacks, anxiety with depression, anxiety causing functional impairment, or any suicidal thought — clinical care, promptly

Cautions and interactions

• Kava carries a hepatotoxicity warning. Avoid with alcohol, in liver disease, and long-term without review.
• Never swallow lavender or any essential oil. The oral lavender evidence is for a specific standardised capsule preparation.
• Herbal sedatives add to alcohol, benzodiazepines and opioids.
• Ashwagandha: case reports of liver injury. Avoid in pregnancy.
• St John's wort interacts with many drugs through CYP3A4 induction and is covered separately.
• Do not use any of these to replace treatment for a severe anxiety disorder.

When this is not a self-care problem — get help

• Any suicidal thought or plan, or self-harm — seek help immediately. In the US, call or text 988. Do not manage this with a supplement.
• Panic attacks with chest pain or breathlessness need assessment to exclude a cardiac cause before being attributed to anxiety.

Known interactions

• Kava + alcohol, benzodiazepines, opioids: additive sedation and liver load.
• Passionflower, valerian, ashwagandha + sedatives: additive sedation.
• St John's wort: broad CYP3A4 induction; see its own page.

Related

• Low mood and depression
• Insomnia: what works before the herbs
• Herb-drug interactions: the ones with numbers behind them
• Herbal liver injury, and the plant that ends the matter

Sources

1. Hormonal Modulation with Withania somnifera: Systematic Review and Meta-Analysis of Randomized-controlled Trials. Planta medica 2026; doi:10.1055/a-2802-8363 PubMed 41740946
2. Effects of aromatherapy on sleep quality in older adults: A meta-analysis. Medicine 2024; doi:10.1097/MD.0000000000040688 PubMed 39654196
3. Effects of Ashwagandha (Withania Somnifera) on stress and anxiety: A systematic review and meta-analysis. Explore (New York, N.Y.) 2024; doi:10.1016/j.explore.2024.103062 PubMed 39348746
4. Clinician guidelines for the treatment of psychiatric disorders with nutraceuticals and phytoceuticals: The World Federation of Societies of Biological Psychiatry (WFSBP) and Canadian Network for Mood and Anxiety Treatments (CANMAT) Taskforce. The world journal of biological psychiatry : the official journal of the World Federation of Societies of Biological Psychiatry 2022; doi:10.1080/15622975.2021.2013041 PubMed 35311615
5. Medicinal herbs for the treatment of anxiety: A systematic review and network meta-analysis. Pharmacological research 2022; doi:10.1016/j.phrs.2022.106204 PubMed 35378276
6. A systematic literature review and meta-analysis of the clinical effects of aroma inhalation therapy on sleep problems. Medicine 2021; doi:10.1097/MD.0000000000024652 PubMed 33655928