Several supplements can meaningfully reduce cortisol levels and improve the fatigue, brain fog, and burnout symptoms often labeled “adrenal fatigue.” Before diving into what works, it’s worth noting that “adrenal fatigue” isn’t a formal medical diagnosis. The Endocrine Society recognizes adrenal insufficiency (Addison’s disease), which is a serious condition requiring medical treatment, but not adrenal fatigue as a separate disorder. That said, the symptoms people describe are real, and the stress-response system they point to is well studied. The supplements below target that system directly.
How Your Stress Response System Works
Your body manages stress through a communication loop between your brain and adrenal glands called the HPA axis. When you’re under stress, your brain signals the adrenal glands to release cortisol. In a healthy system, cortisol rises, does its job, and falls back to baseline. Chronic stress can keep this loop running too hot for too long, leading to disrupted sleep, persistent fatigue, anxiety, and difficulty concentrating. The supplements with the strongest evidence work by calming this loop or supplying raw materials your adrenal glands need to function properly.
Ashwagandha
Ashwagandha is the most studied adaptogen for cortisol reduction. In a randomized, placebo-controlled trial, adults taking 240 mg of a standardized extract daily for eight weeks saw a 23% reduction in serum cortisol compared to placebo, which actually showed a slight cortisol increase. Morning cortisol, the measurement most relevant to that “wired but tired” feeling, dropped significantly. Most previous research used 600 mg daily, so even a lower dose produced clear results. The extract used was standardized to at least 35% withanolide glycosides, which matters if you’re comparing products.
Beyond cortisol numbers, participants reported improvements in stress perception, sleep quality, and overall well-being. Ashwagandha is generally well tolerated, though it can cause mild digestive upset in some people and may interact with thyroid medications.
Rhodiola Rosea
Rhodiola targets the fatigue side of the equation more directly than ashwagandha. Across multiple clinical trials, standardized rhodiola extracts consistently reduced mental and physical fatigue, often within the first week of supplementation, with continued improvement over four to eight weeks. One study in burnout patients found it improved concentration and lowered the cortisol spike that normally occurs upon waking.
Effective doses in trials ranged widely, from 100 mg to 576 mg daily, but most used between 200 and 400 mg of an extract standardized to at least 3% rosavins and 1% salidroside. Rhodiola also improved mood stability, sleep patterns, and motivation in students under academic stress. It works best taken in the morning or early afternoon, as its mild stimulating quality can interfere with sleep if taken late in the day.
Holy Basil (Tulsi)
Holy basil is less well known than ashwagandha or rhodiola but has solid evidence behind it. In an eight-week trial, participants taking a holy basil extract showed significantly lower hair cortisol concentrations compared to placebo. Hair cortisol reflects long-term stress hormone exposure rather than a single-day snapshot, which makes this finding particularly meaningful for people dealing with months of chronic stress.
When researchers exposed participants to an acute laboratory stressor, those on holy basil had lower salivary cortisol, lower blood pressure, and lower subjective stress ratings than the placebo group. Sleep quality also improved. The study used an eight-week supplementation period, so this isn’t an overnight fix, but it suggests holy basil can genuinely dampen an overactive stress response over time.
Phosphatidylserine
Phosphatidylserine is a fat-soluble compound found in cell membranes throughout the brain and body. At 800 mg daily, it reduced cortisol response to intense physical stress by 20 to 30% in clinical studies. A 400 mg dose did not produce significant results compared to placebo, so dosing matters here. It also blunted the release of ACTH, the brain hormone that tells your adrenal glands to produce cortisol in the first place, meaning it works upstream in the stress loop rather than just masking symptoms.
Phosphatidylserine is a reasonable option for people whose fatigue is closely tied to intense physical demands or overtraining, since most of the research has been done in exercise contexts.
Vitamins That Support Adrenal Function
Vitamin C
Your adrenal glands contain one of the highest concentrations of vitamin C in your entire body. This isn’t a coincidence. Vitamin C is a required cofactor for producing both cortisol and adrenaline. When vitamin C is depleted, animal studies show measurably lower stress hormone output and structural changes to the adrenal glands themselves. Chronic stress burns through vitamin C faster than normal, which is why people under sustained pressure may benefit from supplementing even if their diet is reasonable. A daily intake of 500 to 1,000 mg is commonly used for stress support.
B Vitamins, Especially B5
Vitamin B5 (pantothenic acid) is the direct precursor to coenzyme A, which your body uses to synthesize steroid hormones including cortisol. Without adequate B5, the entire hormone production pathway slows down. Deficiency is rare in people eating a varied diet, but stress increases demand for B vitamins across the board. A B-complex supplement covers B5 along with B6 and B12, both of which support energy metabolism and neurotransmitter production.
Magnesium and the Stress Loop
Magnesium plays a direct regulatory role in the HPA axis. Animal research shows that magnesium deficiency increases the expression of stress hormones at the brain level, elevates ACTH release, and produces measurably higher anxiety. Essentially, low magnesium raises the “set point” of your stress response, making your body react more intensely to the same stressor. Correcting a deficiency brings that set point back down.
This matters because magnesium deficiency is common. Estimates suggest roughly half of adults in the U.S. don’t meet the recommended daily intake. Stress itself depletes magnesium through increased urinary excretion, creating a cycle where stress lowers magnesium and low magnesium amplifies stress. Magnesium glycinate and magnesium threonate are the forms most commonly recommended for stress and sleep support, typically at 200 to 400 mg of elemental magnesium daily.
Licorice Root: Effective but Risky
Licorice root shows up frequently in adrenal support formulas, and it does have a real mechanism of action. Its active compound, glycyrrhetinic acid, blocks an enzyme that converts cortisol into its inactive form. The result is that cortisol stays active longer in your body. For someone who genuinely has low cortisol output, this could theoretically help. But for most people searching for adrenal fatigue support, the problem is more likely dysregulated cortisol rather than truly low cortisol.
The bigger concern is safety. By keeping cortisol active longer, licorice root mimics the effects of a hormone that raises blood pressure, causes fluid retention, and depletes potassium. These aren’t rare side effects. They’re the expected pharmacological result of how licorice works. If you have any history of high blood pressure or heart issues, licorice root supplements are best avoided entirely.
Avoid “Adrenal Glandular” Supplements
Supplements marketed as adrenal glandulars, typically derived from bovine adrenal tissue, deserve special caution. A study analyzing over-the-counter adrenal support products found that all of them contained detectable thyroid hormones, and most contained at least one steroid hormone including cortisol, cortisone, and pregnenolone. These are active hormones showing up as unlisted ingredients in unregulated products. Taking them unknowingly can suppress your body’s own hormone production and create the very problem you’re trying to solve. Stick with the well-studied options above rather than gambling on glandular extracts with unpredictable contents.
Putting a Stack Together
If you’re building a supplement regimen for stress-related fatigue, a practical starting point is one adaptogenic herb (ashwagandha for cortisol-dominant symptoms, rhodiola for fatigue-dominant symptoms) paired with magnesium, vitamin C, and a B-complex. These cover the nutritional foundations your stress response system needs while the adaptogen works on the hormonal signaling itself. Give any combination at least four to eight weeks before evaluating results, since most clinical trials show meaningful changes on that timeline. Start with one new supplement at a time so you can identify what’s actually helping and catch any side effects early.