Several supplements have meaningful clinical evidence for reducing anxiety symptoms, with ashwagandha, magnesium, and lavender oil among the most studied. None are a replacement for therapy or medication in severe cases, but for mild to moderate anxiety, the right supplement can make a noticeable difference. Here’s what the research actually supports, how much to take, and what to watch out for.
Ashwagandha
Ashwagandha is one of the best-studied supplements for anxiety, and the evidence is genuinely strong. In a double-blind trial published in Cureus, participants taking 600 mg daily of ashwagandha root extract (KSM-66) for eight weeks saw their cortisol levels drop from an average of 16.12 to 10.86 mcg/dL, a roughly 33% reduction. The lower dose of 250 mg daily also reduced cortisol significantly, though the effect was less dramatic. The 600 mg group showed improvements across every measure of stress, anxiety, and sleep quality used in the study.
Most clinical trials use between 250 and 600 mg per day, split into one or two doses. Effects typically build over several weeks rather than working immediately. Look for standardized root extracts like KSM-66 or Sensoril, which are the forms most commonly tested in research.
Magnesium
Magnesium deficiency is surprisingly common, and low levels are linked to increased anxiety and nervous tension. Supplementing won’t help much if your levels are already adequate, but many people fall short of their daily needs through diet alone.
The form matters more than you might expect. Magnesium glycinate is gentle on the stomach and has calming properties that may directly help with stress, anxiety, and sleep. Magnesium L-threonate is a newer form that crosses the blood-brain barrier more effectively, making it potentially better for mood and cognitive effects. Magnesium citrate is well-absorbed but more likely to cause digestive issues at higher doses. The upper limit for supplemental magnesium is around 350 mg per day. Going above that commonly causes diarrhea.
Lavender Oil Capsules
Oral lavender oil capsules (sold under the brand name Silexan in Europe, and as CalmAid or Lavela in the US) are one of the more surprising entries on this list. A meta-analysis in the European Archives of Psychiatry and Clinical Neuroscience found that 80 mg daily of Silexan produced an effect size of 0.35 for anxiety reduction. That puts it in the same range as SSRIs and SNRIs, the prescription medications most commonly used as first-line treatments for anxiety disorders.
This is specifically about standardized oral capsules containing 80 mg of lavender essential oil, not aromatherapy or putting lavender on your pillow. The capsules can cause fishy-smelling burps in some people, but side effects are otherwise minimal.
Omega-3 Fatty Acids
Fish oil supplements with high EPA content show promise for anxiety, though the evidence is less consistent than for ashwagandha or lavender. One intervention trial found significant reductions in anxiety with a daily dose of 2,250 mg EPA plus 500 mg DHA over 12 weeks. EPA appears to be the more important component for anxiety specifically, while DHA may help more with irritability and anger.
Most over-the-counter fish oil capsules contain far less EPA than the amounts used in trials. If you’re taking fish oil for anxiety, check the label for EPA content specifically. You’ll likely need multiple capsules to reach a meaningful dose, or look for concentrated EPA formulas.
L-Theanine
L-theanine is an amino acid found naturally in green tea. It promotes alpha brain wave activity, the pattern associated with relaxed alertness, similar to what you’d see during meditation. Unlike most supplements on this list, L-theanine works relatively quickly, often within 30 to 60 minutes. Typical doses in studies range from 100 to 200 mg. It’s one of the few supplements that reduces anxiety without causing drowsiness, making it useful during the workday or before stressful events like presentations.
Passionflower
Passionflower (Passiflora incarnata) works through a mechanism that most calming supplements don’t. Research has shown it directly interacts with GABA receptors in the brain, the same system targeted by prescription anti-anxiety medications like benzodiazepines. Notably, passionflower binds to a different site on the GABA-A receptor than benzodiazepines do, and it also affects GABA-B receptors and GABA uptake. This broader interaction with the calming system in the brain may explain why many people find it effective for acute, in-the-moment anxiety. Typical doses in studies use around 425 mg of a dry extract.
Saffron
Saffron extract at 30 mg daily has shown anxiety-reducing effects in several trials. A meta-analysis comparing saffron head-to-head with SSRIs found no significant difference between the two for anxiety symptoms. That’s a notable finding: in the small number of studies that made this comparison, saffron performed essentially as well as prescription medication. The evidence base is still small, but saffron is worth considering, particularly if you’re looking for something with mood-brightening effects alongside anxiety relief.
Vitamin D
Vitamin D isn’t a direct anti-anxiety supplement, but being deficient in it significantly raises your risk of anxiety symptoms. A large study in Psychiatry Investigation found that people with severe vitamin D deficiency (blood levels below 10 ng/mL) had a 70% higher risk of clinically significant anxiety compared to those with adequate levels. Even moderate insufficiency (10 to 20 ng/mL) was associated with a 22% increased risk.
If you haven’t had your vitamin D levels checked, it’s worth doing, especially if you live in a northern climate, spend most of your time indoors, or have darker skin. Getting your levels above 20 ng/mL is the minimum threshold, though many practitioners aim for 30 ng/mL or higher.
Valerian Root
Valerian root is better known as a sleep aid, and that’s where the strongest evidence lies. But it has a long history of use for anxiety in Europe, where it’s an accepted over-the-counter treatment for stress and nervous tension in countries including Germany, Switzerland, and Italy. Clinical trials show it improves both sleep quality and anxiety symptoms. If your anxiety is worst at night or closely tied to poor sleep, valerian may address both problems at once. It works best as a regular supplement rather than an as-needed one.
Kava
Kava is effective for anxiety, but it comes with important safety caveats. The recommended dose is 60 to 120 mg of kavalactones per day, used for no more than three months at a time. Reports of liver toxicity have largely occurred in people who exceeded those limits or used poorly prepared products.
The preparation method matters enormously for safety. Traditional water-based extractions pull out only about 3% of kavalactones, but they also retain a compound called glutathione that helps protect the liver from toxic byproducts. Alcohol and acetone extractions pull out over 95% of kavalactones but lose that protective factor. Safety experts recommend using water extracts made from peeled noble kava roots, which is how Pacific Island cultures have consumed it safely for centuries. If you choose kava, avoid alcohol entirely while taking it and select products that specify water extraction.
What to Avoid Combining With Medications
If you’re taking an SSRI, SNRI, or any other serotonin-affecting medication, be cautious with 5-HTP and St. John’s Wort. Both increase serotonin levels, and combining them with prescription antidepressants can push serotonin dangerously high. 5-HTP in particular is absorbed rapidly, causing sharp spikes in serotonin that make timing and dosing unpredictable. While some research suggests that slow-release formulations of 5-HTP may be safer alongside SSRIs, this is not something to experiment with on your own.
Most of the other supplements on this list have relatively few interactions with prescription medications. Ashwagandha, magnesium, L-theanine, and omega-3s are generally well-tolerated alongside standard treatments. Kava should not be combined with alcohol or medications that affect the liver.