What happens when you take ashwagandha with reishi?
Ashwagandha (Withania somnifera) and reishi (Ganoderma lucidum) are both classified as adaptogens, which is a loose category for plants and fungi that appear to help the body recalibrate after stress. They work on different pieces of the stress response, which is why they are often paired in stress-and-sleep formulas.
Ashwagandha is best documented as an HPA-axis modulator. Multiple randomized controlled trials have shown that 300-600 mg per day of standardized root extracts reduces morning serum cortisol, lowers self-reported stress on the Perceived Stress Scale (PSS) and the DASS-21, and modestly improves sleep quality and anxiety scores. The proposed mechanism involves withanolides binding to GABA-A receptors and modulating the hypothalamic feedback that drives cortisol output.
Reishi has a different profile. Its bioactives are beta-glucans (immunomodulating polysaccharides) and triterpenes such as ganoderic acids. Reishi has been used in East Asian medicine for centuries for what we would now call "low energy with insomnia," and modern data shows immune-modulating, antioxidant, and mild parasympathetic effects. It is not a sedative in the GABAergic sense; it is more of a tonic that supports the rest-and-digest side of the autonomic nervous system.
In 2025, Pham and colleagues published the first dedicated RCT of an ashwagandha-plus-reishi combination in Current Developments in Nutrition. They randomized 499 healthy adults to either the combination supplement or placebo for 6 weeks. The supplement group showed a statistically significant reduction in perceived stress on the NIH Toolbox Perceived Stress Survey, with no excess adverse events.
Why is this important?
Most stress and sleep problems are not caused by a single broken system. They involve elevated cortisol, dysregulated autonomic tone, poor sleep architecture, and often immune-inflammatory disturbance. Stacking a cortisol-lowering adaptogen with a parasympathetic-supporting medicinal mushroom is a reasonable way to address more than one of those at once.
The combination is also attractive because the two ingredients have very different safety and side-effect profiles. Ashwagandha can occasionally over-do its sedating effect, and there are rare reports of hepatotoxicity. Reishi can mildly thin the blood and occasionally cause GI upset. Combining them at moderate doses, rather than pushing either to a high dose alone, tends to be better tolerated.
Most existing stress-supplement RCTs are short (4-8 weeks) and use composite outcomes. The Pham 2025 trial is notable for being relatively large and using validated PROMIS instruments, even though it was industry-funded (MegaFood). That funding is a real limitation, but the methodology is solid enough that the result is worth taking seriously as supportive evidence rather than fabricated marketing.
What should you do?
For garden-variety chronic stress with mildly disrupted sleep, a reasonable protocol is 300-600 mg/day of a standardized ashwagandha extract (KSM-66 or Sensoril are the best-studied brands) paired with 1-2 g/day of a dual-extract reishi. Dual extract means the manufacturer uses both water and alcohol extraction so you get the polysaccharides and the triterpenes. Powdered ground mushroom alone is much less concentrated.
Ashwagandha can be taken in the morning or evening; many people prefer evening because of the mild sedating effect. Reishi is traditionally taken away from meals. Give the combination at least 4-6 weeks before judging whether it is working, because the effects build gradually.
Skip ashwagandha in pregnancy (it has uterine-stimulating activity in animal models), in active hyperthyroidism (it can push thyroid hormone up), and during active autoimmune flares without medical guidance. Reishi mildly inhibits platelet aggregation and CYP enzymes, so people on warfarin, antiplatelet drugs, or chemotherapy should clear it with a clinician first. People on immunosuppressants after organ transplant should generally avoid both.
Watch for signs of over-sedation, especially in the first week. If you feel groggy in the morning, cut the dose or move the ashwagandha earlier in the day.
Which specific products are affected?
Many "stress complex" and "adrenal support" supplements include both ingredients alongside other adaptogens like rhodiola, holy basil, schisandra, or eleuthero. Functional mushroom blends sold by major brands often pair reishi with ashwagandha plus lion's mane and cordyceps in nighttime formulations.
The KSM-66 brand of ashwagandha (standardized to >5% withanolides) and the Sensoril brand (standardized to >10% withanolide glycosides) have the most clinical research behind them. For reishi, look for a dual extract standardized to a stated percentage of beta-glucans and triterpenes; products that just say "reishi mycelium grown on grain" are typically much lower in active compounds than fruiting body extracts.
Avoid combining this stack with prescription anxiolytics or sedatives without medical advice, and be cautious if you are already taking other adaptogens at full clinical doses; you can run into a too-much-of-a-good-thing flatness or fatigue.
The bottom line
Ashwagandha and reishi are a complementary pair: ashwagandha pulls down elevated cortisol through the HPA axis, reishi supports parasympathetic and immune balance. A 2025 RCT in nearly 500 adults showed the combination reduced perceived stress over 6 weeks. For chronic, low-grade stress with sleep disturbance, 300-600 mg of standardized ashwagandha plus 1-2 g of dual-extract reishi is a defensible starting stack, with the usual exclusions for pregnancy, hyperthyroidism, and immunosuppressant use.