Ashwagandha shows genuine promise for reducing anxiety, with multiple clinical trials finding it outperforms placebo over periods of 30 to 90 days. The evidence is strongest for mild to moderate stress and anxiety in otherwise healthy adults, not for diagnosed anxiety disorders requiring clinical treatment. It’s a reasonable supplement to consider, but it comes with real caveats around safety, thyroid effects, and product quality.
What the Clinical Evidence Shows
Across several randomized, placebo-controlled trials, a total of nearly 500 adults with self-reported high stress or diagnosed anxiety took ashwagandha root extract for six to eight weeks. Compared to placebo groups, participants taking ashwagandha consistently reported lower anxiety and stress scores on validated rating scales. These weren’t massive trials, and most were conducted in India, but the pattern is fairly consistent: ashwagandha reduces subjective anxiety more than a sugar pill.
One trial gave participants either 225 mg or 400 mg daily of an ashwagandha root and leaf extract for 30 days. Both doses produced measurable improvements in stress, anxiety, and even depression scores compared to placebo. Another study followed 54 people with mild to moderate stress and anxiety for 60 days, finding significantly lower scores on two different anxiety rating scales in the ashwagandha group. A trial at the University of Colorado tested ashwagandha root extract in 60 college students over 30 days and also found positive results.
The consistent finding across these studies is that ashwagandha helps with the kind of anxiety most people experience: stress-driven, situational, and not severe enough to be debilitating. If you’re dealing with a clinical anxiety disorder, the evidence base is much thinner, and ashwagandha shouldn’t replace conventional treatment.
How It Works in the Body
Ashwagandha’s active compounds (called withanolides) appear to work through two main pathways. First, they help regulate the body’s stress response system, the loop connecting the brain’s hypothalamus, pituitary gland, and adrenal glands. This system controls cortisol release. Ashwagandha reduces the signaling that triggers cortisol production, which is why people often describe feeling calmer and less reactive to stress after taking it for a few weeks.
Second, ashwagandha influences brain chemistry more directly by affecting the same calming neurotransmitter system that anti-anxiety medications target, along with serotonin levels. This dual action, lowering the body’s stress hormone output while also promoting calming brain signals, likely explains why it performs better than many other herbal supplements in anxiety trials.
How Long Before You Notice a Difference
This isn’t something that works the first day you take it. Clinical trials measured outcomes at 30, 60, and 90 days, with benefits appearing as early as four weeks in some studies. The 60-day mark tends to be where the most consistent improvements show up on anxiety rating scales. If you’ve been taking ashwagandha for eight weeks and feel no different, it’s probably not going to work for you.
Doses used in successful trials ranged from 225 mg to 600 mg daily of standardized root extract, taken in capsule form. The lower end of that range still produced results in at least one trial, so more isn’t necessarily better. Look for products standardized to a specific withanolide percentage, which indicates the concentration of active compounds has been measured.
Side Effects and Safety Risks
Most people tolerate ashwagandha without problems, but the side effects that do occur can be surprisingly intense. Australia’s Therapeutic Goods Administration has been tracking reports of sudden, severe nausea, vomiting, and diarrhea in some users, sometimes after just one or two doses. In several cases, the reaction was initially mistaken for food poisoning. Sixteen cases were severe enough to require hospitalization. Symptoms resolved after stopping the supplement.
More concerning is a rare but real risk of liver injury. As of early 2024, Australia’s drug regulator had received 12 reports of liver problems linked to ashwagandha, with four of those cases requiring hospitalization. Most patients recovered after discontinuing use, though some needed medical treatment. If you notice yellowing skin or eyes, dark urine, unusual fatigue, or upper abdominal pain while taking ashwagandha, stop immediately. Anyone with a history of liver disease should avoid it entirely.
Thyroid Effects Worth Knowing About
Ashwagandha actively increases thyroid hormone production. In one study of people with mildly underactive thyroids, the active thyroid hormone T3 increased by 41.5% after eight weeks of supplementation, while T4 rose by nearly 20%. The hormone that signals the thyroid to work harder (TSH) dropped by 17.4% over the same period.
For someone with a sluggish thyroid, this might sound appealing, but it creates a serious problem for anyone with an overactive thyroid. Ashwagandha can worsen hyperthyroidism symptoms, including restlessness, anxiety (ironically the thing you’re trying to treat), hand tremors, and heart palpitations. If you have any thyroid condition or are taking thyroid medication, this interaction matters.
Who Should Avoid It
The German Federal Institute for Risk Assessment recommends that pregnant women, breastfeeding women, children, and people with liver disease avoid ashwagandha supplements. The pregnancy concern is notable: ashwagandha has historically been used as a substance to induce miscarriage, and there’s no modern safety data for pregnant or breastfeeding populations. There’s simply no reason to take the risk.
People already taking medications for thyroid conditions, anxiety, or sleep should be cautious about adding ashwagandha, since it affects overlapping systems. And because ashwagandha supplements are not regulated like prescription drugs in most countries, product quality varies widely. The Philippines FDA issued a 2025 warning against a specific ashwagandha product sold at 3,000 mg per capsule that had never been evaluated for safety. Sticking with established brands that provide third-party testing is one of the few ways to reduce your risk of getting a contaminated or mislabeled product.
The Bottom Line on Anxiety Relief
Ashwagandha is one of the better-studied herbal options for everyday anxiety and stress, with real clinical trial data behind it. Doses of 225 to 600 mg daily of standardized root extract, taken consistently for at least 30 to 60 days, have shown measurable reductions in anxiety across multiple trials. It’s not a substitute for therapy or medication in cases of clinical anxiety, but for the kind of persistent, low-grade stress that grinds people down, it’s a reasonable option with a plausible biological mechanism. Just go in aware of the thyroid effects, the small but real liver risk, and the fact that supplement quality is your responsibility to verify.