The short answer: reishi on its own has not been shown to make people sleepy. The sleep studies on reishi itself are in rats and mice, and insomnia actually appears on its list of reported side effects. The drowsiness people describe usually belongs to what gets stacked beside it: valerian, passion flower, lemon balm. Reishi’s real caution is interactions, especially blood thinners.
Most pages that answer “does reishi make you sleepy” answer for the jar, not the mushroom. That’s a problem, because almost nobody sells reishi on its own in the evening aisle. It arrives in a calm blend, next to herbs with their own research and their own cautions. This page separates the two, then covers timing, daily use, the liver question, and the medicines worth asking about before you start.
Every safety and interaction statement below links to its source. The list is at the bottom, with the date we read them.
Does reishi make you sleepy?
What the research on reishi itself shows
Reishi (Ganoderma lucidum) has a long record in East Asian herbal tradition as a calming tonic. The modern sleep research is thinner than that reputation suggests, and nearly all of it is in animals. An extract of the fruiting body increased total sleep time in rats over three days of dosing. A mycelium extract shortened sleep latency in mice that had also been given a sedative, and the effect disappeared when the researchers wiped out the animals’ gut bacteria.
That is interesting lab work. It is not evidence that reishi makes a person drowsy.
The human safety record points, if anything, the other way. Memorial Sloan Kettering lists insomnia among reishi’s reported side effects, alongside nausea, dry mouth and vertigo. The Merck Manual lists nausea, insomnia, liver toxicity, anorexia and chronic diarrhea as reported. A small placebo-controlled trial in 16 healthy volunteers tested 2 g of reishi extract twice a day for 10 days. It was designed to measure safety, not sleep, and reported no adverse effects compared with placebo.
So the plain version: reishi has been studied for sleep in rodents. In people, the data we could find doesn’t show it working as a sedative.
The botanicals usually stacked beside it
This is where the drowsiness question actually lives. Here’s what the sources say about the four ingredients most often sold with reishi, and the amounts that research used.
| Ingredient | What the source says about drowsiness | Amounts in the research |
|---|---|---|
| Valerian root | NIH’s NCCIH says it’s possible, though not proven, that valerian might have a sleep-inducing effect, and calls the sleep evidence inconsistent | 300–600 mg daily in safety data |
| Passion flower | NCCIH lists drowsiness, dizziness and confusion as possible side effects | Teas and extracts; no single dose given |
| Lemon balm | In one crossover trial, self-rated alertness fell at every time point after a 900 mg dose, and calmness rose early after 300 mg | 300–900 mg, single doses |
| L-theanine | MSKCC notes that taking it with prescription sleep medicines may increase drowsiness | 200 mg/day in a four-week trial |
If a reishi product makes you feel sleepy, look at the other names on the panel first. And if the amounts aren’t printed, you can’t tell which ingredient is doing it. What’s actually in a “calm blend” explains why.
What that means for Flow Botanicals’ reishi gummies
Our Reishi Relax Gummies carry 200 mg reishi extract plus 25 mg each of L-theanine, lemon balm, passion flower and valerian root per gummy, at 1–2 gummies daily. They contain sugar.
It’s an evening wind-down formula, and we label it that way on purpose. It supports relaxation and a healthy response to occasional stress. Now read the table above against those numbers: 25–50 mg of valerian, lemon balm and L-theanine is well below the amounts in the research. So we make no promise that it will make you drowsy, and no promise that it won’t. There is no trial on this finished formula. What we can promise is that every amount is printed, so you can check.
Should you take reishi in the morning or at night?
We found no human study that compares morning and evening reishi. Timing advice online is mostly inherited from the calm-blend positioning, not tested.
Two practical rules follow from the sections above. If your product is reishi alone, no source we found supports a particular time of day, so follow the label. If it’s a blend with valerian, passion flower or lemon balm, treat it as an evening product until you know how it affects you, because passion flower’s listed side effects include drowsiness and dizziness. That’s also why our own gummy is positioned for the evening rather than for daytime focus.
What not to mix with reishi
This is the section to read twice. None of it means reishi is dangerous for most people. It means these are the specific combinations authoritative sources flag, and they’re worth a conversation with your doctor or pharmacist before you start. Nothing on this page means a supplement is safe with your medications. Only your prescriber can answer that for you.
| If you take or have… | What the source says | Strength of evidence | Source |
|---|---|---|---|
| Blood thinners or antiplatelet drugs (e.g. warfarin) | Reishi can increase the risk of bleeding | Listed interaction | MSKCC, Merck Manual |
| Blood-sugar-lowering medication | Possible additive low blood sugar | Listed interaction | Merck Manual |
| Blood pressure medication | May produce low blood pressure | Listed interaction | Merck Manual |
| Immunosuppressants | Reishi can enhance immune response; MSKCC says it may not be safe for you | Listed interaction | MSKCC |
| Chemotherapy | Raises antioxidant capacity, which in theory may interact with some agents | Theoretical | MSKCC |
| Drugs processed by CYP1A2, CYP2E1 or CYP3A liver enzymes | Reishi polysaccharides inhibited these enzymes | Test tube only | MSKCC |
| Blend ingredients: alcohol or sedatives | Valerian should not be taken with alcohol or sedatives | Precaution | NCCIH |
| Blend ingredients: prescription sleep medicines | L-theanine may increase drowsiness | Precaution | MSKCC |
| Blend ingredients: surgery within 2 weeks | Tell your provider if you take passion flower | Precaution | NCCIH |
| Blend ingredients: pregnancy | Passion flower should not be used during pregnancy | Precaution | NCCIH |
The bottom rows matter for our own gummy: it contains valerian, L-theanine and passion flower. Cordyceps has an overlapping bleeding caution, covered in cordyceps dose and interactions. If you take both mushrooms and a blood thinner, that’s two flags on the same issue.
What happens if you take reishi every day?
Most reishi products, ours included, are labelled for daily use. LiverTox, the NIH’s drug-induced liver injury database, says reishi is well tolerated and that the usual dose ranges from 500 mg to 3 grams daily. Merck notes that long-term safety has been reported, but that there’s no information on use in pregnancy or breastfeeding.
Two honest caveats. First, those dose ranges describe reishi products in general, and an extract’s milligrams aren’t directly comparable to raw powder unless the extract ratio is printed. Ours isn’t, and we don’t disclose fruiting body versus mycelium either, so compare with care. Second, the side effects above (nausea, insomnia, digestive upset) were reported with use, so daily use is when you’d notice them. If something changes, stop and tell your doctor.
As for results: we don’t give a timeline, because no trial exists on our formula to base one on.
Can reishi hurt your liver?
Rarely, and the evidence is weak, but the question is fair and we’d rather answer it straight.
LiverTox gives reishi a likelihood score of D, a “possible rare cause” of clinically apparent liver injury. It hasn’t been linked to liver enzyme rises in clinical trials. There are isolated case reports, including a fatal case after a switch to a powdered product, but LiverTox says many were poorly documented and that other causes of liver injury weren’t always ruled out. Its conclusion is that, given how widely reishi is used, liver injury from it must be extremely rare. A 2023 case report described acute liver injury after reishi powder taken with alcohol, which resolved within two weeks.
Practical version: if you have liver disease or drink heavily, ask first. If you notice dark urine, yellowing skin or eyes, or unusual fatigue while taking any supplement, stop and see a doctor.
Reishi vs lion’s mane: which is better?
They aren’t competing for the same job, so “better” depends on the time of day you’re shopping for. Reishi’s reputation, and our gummy, sit at the evening end. Lion’s mane has been studied for cognition in small human trials with mixed results: a 28-day pilot at 1.8 g found a quicker Stroop result after one dose and only a trend in stress, and a single 3 g dose showed no overall effect on cognition or mood.
If lion’s mane is the one you’re weighing, lion’s mane dosage covers amounts and timing the same way this page does. Before buying either, how to read a mushroom supplement label shows what to check on the panel.
Frequently asked questions
What are the side effects of reishi?
Reported side effects include nausea, insomnia, dry mouth, constipation, itching and vertigo, per MSKCC. Merck also lists liver toxicity, loss of appetite and chronic diarrhea. Rare liver case reports exist (see above).
Does reishi interact with blood thinners?
Yes, it’s the most consistently listed interaction. Both MSKCC and Merck say reishi may increase bleeding risk with anticoagulant and antiplatelet drugs. Talk to your prescriber first.
Can I drink alcohol with reishi?
We’d skip it with a blend. NCCIH says valerian should not be taken with alcohol or sedatives, and one case report describes liver injury after reishi powder plus alcohol.
Is reishi safe during pregnancy?
There isn’t enough information to say. Merck reports no information on reishi in pregnancy or breastfeeding, and NCCIH says passion flower, common in reishi blends, should not be used during pregnancy. Ask your doctor before using any reishi product.
Is reishi different for women and men?
None of the sources on this page give sex-specific doses or cautions. The pregnancy and breastfeeding point above is the one difference that matters.
Can I take reishi and cordyceps together?
We found no source testing the combination. Both carry a bleeding caution (reishi, cordyceps), so anyone on blood thinners should ask first. The full cordyceps picture is in cordyceps dose and interactions.
Sources
All accessed September 2026. Where a page shows its own revision date, it’s noted.
- Memorial Sloan Kettering Cancer Center, About Herbs: Reishi Mushroom (updated May 5, 2026)
- Memorial Sloan Kettering Cancer Center, About Herbs: L-Theanine (updated July 14, 2026)
- Memorial Sloan Kettering Cancer Center, About Herbs: Cordyceps
- Merck Manual Professional Edition: Reishi
- NIH LiverTox: Lingzhi, Reishi (updated October 5, 2024)
- NIH NCCIH: Valerian
- NIH NCCIH: Passionflower
- Cui XY et al. Extract of Ganoderma lucidum prolongs sleep time in rats. J Ethnopharmacol, 2012. PubMed 22207209
- Yao C et al. Ganoderma lucidum promotes sleep through a gut microbiota-dependent and serotonin-involved pathway in mice. Sci Rep, 2021. PubMed 34211003
- Wicks SM et al. Safety and tolerability of Ganoderma lucidum in healthy subjects. Am J Chin Med, 2007. PubMed 17597499
- Kennedy DO et al. Modulation of mood and cognitive performance following acute administration of Melissa officinalis (lemon balm). Pharmacol Biochem Behav, 2002. PubMed 12062586
- Hidese S et al. Effects of L-theanine administration on stress-related symptoms and cognitive functions in healthy adults. Nutrients, 2019. PubMed 31623400
- Guedikian R et al. Ganoderma lingzhi (reishi mushroom)-induced acute liver injury in the setting of alcohol use. Cureus, 2023. PubMed 37885515
- Docherty S et al. The acute and chronic effects of lion’s mane mushroom supplementation on cognitive function, stress and mood in young adults. Nutrients, 2023. PubMed 38004235
- Surendran G et al. Acute effects of a standardised extract of Hericium erinaceus on cognition and mood in healthy younger adults. Front Nutr, 2025. PubMed 40276537
This page is general information about ingredients, not medical advice. If you take prescription medication, are pregnant or nursing, or have a medical condition, talk to your doctor or pharmacist before taking reishi or any supplement.