So given all that, is Lion’s mane safe to take? Studies on human, on rodents and in labs have all largely shown Lion’s Mane negative side effects to be minimal. Both traditional knowledge and modern science agree that Lion’s Mane is generally safe to consume and mostly well-tolerated. Nevertheless, there have been a few instances of side effects found in some of these recent studies.

First off, we should note that individuals allergic to mushrooms should avoid taking Lion’s Mane or any products derived from Lion’s Mane. There have been a few documented cases of individuals experiencing trouble breathing or skin rashes after taking Lion’s Mane, likely related to mushroom allergies (1, 2, 3).

There are a few other reports of folks experiencing digestive issues such as G.I. discomfort, abdominal pain, and diarrhea after consuming Lion’s Mane (2, 3, 21). There’s at least one reported example of an individual experiencing an acute hypersensitivity reaction to Lion’s Mane (21). In general, these negative reactions were described as mostly mild and typically short-lived. If you experience any unwanted side effect of Lion’s Mane, consider trying another mushroom, or different nootropic altogether.

Learn about the benefits of other mushrooms

It’s important to note that Lion’s Mane may slow blood clotting and affect blood sugar regulation. There are few studies examining Lion’s Mane interactions with any specific medications, but as a general rule, Lion’s Mane may interact with any medication intended to increase blood clotting. For example, if you’re taking anticoagulants or medications for diabetes, check with your doctor before using any Lion’s Mane supplements (22).

Learn more about Lion's Mane potential interactions

Nootropics, which are sometimes also called cognitive enhancers or “smart drugs,” are a loosely defined group of supplements used to boost brain functioning and cognition. Lion’s Mane as a supplement is often used as a nootropic given its reputation for improving brain functions such as memory, focus and alertness.

We know about Lion’s Mane supplement side effects, but what side effects of nootropic drugs have been reported? For starters, a few of the more commonly used nootropics have some known side effects. For example, ginkgo is known to cause blood thinning (5); ashwagandha can act as a sedative in large doses (5); ginseng and eleuthero have been contraindicated in folks experiencing hypertension; dihydroergeotoxine has been contraindicated in individuals dealing with psychosis; and rhodiola is not recommended for patients with manic-depressive psychosis.

One study found that nootropics may be paradoxically associated with a slight decline in both short- and long-term cognition, a decrease in plastic learning ability, and potential for addictive behaviors (6). This is not too dissimilar to caffeine, which is widely used by healthy folks for its cognitive effects. We therefore advise that you approach these nootropics with the same level of caution as you would caffeine. Taking too much of one or several nootropics can overwhelm the brain and the gut with too much bio-activity (8). Therefore, responsible use is key as is following recommended dosages.

There are a few commonly reported but relatively rare side-effects of nootropics as a general category, including brain fog, headaches, digestive discomfort, and insomnia (8). Finally, we should note there are some exceedingly rare side effects that have been reported, including mood imbalance, lightheadedness, tiredness, jitters, and strange or lucid dreaming (which may be considered a neutral or even positive effect for some but a negative effect for others).

Now, I’ve poked my nose around the web and I’ve read of some truly unfortunate and negative experiences that folks have had with Lion’s Mane. Some people have reported increasing mental health struggles, decreasing physical energy energy, or bad physical reactions. This is all anecdotal evidence, but nevertheless there are some who do question is Lion’s Mane mushroom safe at all? The simple answer is that real and high quality Lion’s Mane products are largely safe to consume. It’s the less than reputable supplements out there that may or may not contain real Lion’s Mane that are of more concern.

I can’t say for sure, but based on the reporting of these individuals on reddit, one common denominator is often that the Lion’s Mane or associated extracts they consumed came from dubious sources with poor to no quality control.

The unfortunate truth of the mushroom supplements industry is that there are a lot of products on the market, especially those made in or sourced from China, whose quality is almost difficult to verify. Other brands will use powder extracts of dubious origin and contents and selling them as Lion’s Mane. If you’ve ever heard of anyone reporting negative Lion’s Mane powder side effects, it’s likely that the sourcing and quality is to blame (if what they were taking was even Lion’s Mane in the first place.)  

Learn more about why you should be wary of mushroom extract powders.

Real Lion’s Mane mushrooms are much safer to consume than whatever is in these powders and extracts. But because the market is flooded with these low quality supplements, it’s important to do some research on any given product so you can know where it came from and what’s in it before putting it in your body.

So given all of that, I think it’s safe to say that properly sourced and quality controlled Lion’s Mane has relatively few side effects and is broadly considered safe. There are a few risks to be aware of, especially if you have mushroom allergies or take blood clotting medications, but a careful and conscientious consumer should be able to find and take Lion’s Mane supplements with little cause for concern. At Birch Boys, it’s our belief that the benefits of Lion’s Mane tincture greatly outweigh any potential risk factors.

Learn more about benefits of Lion's Mane