Can magic mushrooms go bad? What studies show about breakdown, mould and safety

People ask whether magic mushrooms “go bad” for two different reasons. One is chemistry: does the psilocybin in them break down over time? The other is spoilage: can they rot or grow mould the way other mushrooms and foods do? A third question sits under both: if something has changed, can you tell? This article takes them in turn, using laboratory studies for the first and official food-safety and poison-centre sources for the rest.

We report what researchers measured and under what conditions. We do not give storage tips, shelf lives or ways to keep anything, and nothing here suggests that a mushroom of any age is safe to eat.

How strong is the evidence?

We label each finding. Established: official sources or several studies agree. Preliminary: one study, or a small sample. Unresolved: the question has not been answered. Limited evidence: we could open only a thin or indirect source.

The evidence on breakdown is thin. We found a handful of laboratory studies, each looking at a different kind of sample: freshly grown mushrooms, decades-old museum specimens, user-supplied dried samples, chemical reference solutions and blood. None was designed to answer the everyday question “how long do magic mushrooms last?”, and we do not try to answer it either. On spoilage, we found no official Canadian source that discusses psilocybin mushrooms specifically, so we report what food-safety agencies say about mouldy food in general.

Does psilocybin break down in stored mushrooms?

Yes, according to the studies we found, though how fast and how much varies a great deal. The clearest test is a 2021 study that used freshly cultivated Psilocybe cubensis to monitor the stability of psilocybin and four related compounds under different storage and processing conditions. The authors report that the amount of breakdown differed markedly between the conditions they tested, and that content also varied widely between individual mushrooms (Gotvaldová et al., 2021). Evidence: preliminary. It is one study of one species, and a later paper notes that it covered only a single year (Bradshaw et al., 2022).

The longest view comes from a 2022 study of mushroom specimens kept in museum collections (fungaria). The team measured psilocybin, psilocin and related compounds in 25 specimens of three species, collected over roughly five decades. They report “taxon- and time-dependent decay” of psilocybin and psilocin, with some specimens having no detectable quantities (Bradshaw et al., 2022). Evidence: preliminary.

The details show how uneven the losses were. Very few P. cubensis specimens had detectable psilocybin or psilocin, while most P. cyanescens specimens still had both, though reduced, after nearly 50 years. In P. semilanceata, the liberty cap, specimens older than about 20 years had barely detectable levels, and the oldest had very little psilocybin and no detectable psilocin. Yet the authors also found that specimen age was poorly correlated with the amount of these compounds: some specimens under 20 years old had almost none (Bradshaw et al., 2022).

The authors are careful about what this proves. They say the sample size for any given age was small, that the original preservation method was often unknown, and that a study designed specifically to test breakdown over time, with replicates and controls, would be needed to find the causes. Their summary is that the presence and amounts of psilocybin and psilocin in these specimens are “highly unpredictable” (Bradshaw et al., 2022).

A 2025 study that measured dried P. cubensis found large differences in total content and in the balance of psilocybin to psilocin between samples supplied by users and samples grown in a laboratory. The authors suggest that a user-supplied sample had possibly been exposed to moisture, promoting the breakdown of psilocybin into psilocin, but they did not test this directly (Rodríguez et al., 2025). Evidence: preliminary, and the explanation is the authors’ interpretation.

What about psilocin in solutions, extracts and lab samples?

Psilocin, the compound the body forms from psilocybin, is the less stable of the two. Forensic chemists have had to deal with this because it affects their test results. A 2006 study of psilocin and psilocybin reference standards dissolved in water, followed for 14 days, found that keeping light out significantly prolonged the useful life of the standards, with both stable over seven days (Anastos et al., 2006). Evidence: preliminary, and it concerns pure laboratory chemicals.

A 2012 forensic study of psilocin in blood describes it as an unstable analyte. Blood samples held at room temperature showed a continuous decrease, with a loss of about 90% after one week; refrigeration improved stability significantly, and freezing led to a loss that could not be reproduced (Martin et al., 2012). Evidence: preliminary. This is about testing blood for psilocin after use, not about mushrooms, but it shows why measured levels depend heavily on how and how long a sample was held. Our guide to how long psilocybin stays in your system covers testing more broadly.

The 2025 team also reports that, during their own extraction work, longer methods carried a higher risk of breaking down the compounds, shown by the formation of bluish psilocin products (Rodríguez et al., 2025). That blue colour is the same family of reaction behind bruising; we explain it, and why it is not a test of anything, in why magic mushrooms turn blue. We found no study of how stable psilocybin is in homemade or commercial edibles, so we cannot say anything about them. For the chemistry of the two compounds, see psilocin vs psilocybin.

Why breakdown makes strength unpredictable

Mushrooms vary before any breakdown begins. Health Canada says the strength of magic mushrooms can vary greatly, and that one mushroom may have different concentrations of the active ingredients compared to another (Health Canada). The 2021 study found tryptamine concentrations in individual fruiting bodies to be highly variable, even among mushrooms grown together (Gotvaldová et al., 2021). Evidence: established.

Breakdown adds a second, uneven layer on top. The museum study found age to be a poor guide to content, and the authors point to species, original preservation and age all playing a part (Bradshaw et al., 2022). Put together, these findings mean that an older mushroom is not reliably weaker, a fresh-looking one is not reliably stronger, and no one can judge content by eye. That last step is our reading of the studies, not a quotation.

It also means that a number from any study describes one sample at one moment. We look at what laboratory potency figures can and cannot tell you in what lab studies establish about mushroom potency claims. For the risks of unpredictable strength, see are magic mushrooms safe? and can you overdose on magic mushrooms?

Can magic mushrooms go mouldy or spoil?

Mushrooms are organic material, and official food-safety guidance on mould applies to foods in general. We found no Canadian or other official source that addresses psilocybin mushrooms specifically, so what follows is general food-safety advice, not a finding about magic mushrooms. Evidence: established for food in general; limited evidence for this material.

Health Canada says mycotoxins are toxic chemical products formed by fungi, that there are now more than 300 known, and that they can affect foods such as cereals, nuts, dried fruit, cocoa and spices. Its advice is direct: avoid eating mouldy nuts or other mouldy foods. It gives two reasons: mycotoxins may be present in those foods, and the conditions that allow mould to grow could also allow the growth of harmful bacteria that cause food poisoning (Health Canada, Natural Toxins). It adds that some moulds are used deliberately, as in blue cheese, and are not harmful.

HealthLink BC, the British Columbia health information service, says mould on moist foods can be growing under the surface, that these foods may also be contaminated with bacteria and should be thrown away, and that food which is very mouldy should be thrown away (HealthLink BC). Its list of foods that can still be used after mould is cut away does not include mushrooms, and we do not extend it to them.

The broader point from Health Canada is that you cannot tell if food is unsafe by its smell or taste, and that colour does not always tell you either. Its rule is “When in doubt, throw it out!” (Health Canada, Food safety and you).

Can you tell by look or smell whether a mushroom is safe?

No, and this is the more important safety point. Spoilage is only one way a mushroom can be dangerous. Health Canada says that since many species look alike, it can be hard to tell them apart, and that it is possible for people to consume poisonous mushrooms, mistaking them for magic mushrooms (Health Canada).

The Ontario Poison Centre says only a mushroom expert, called a mycologist, can tell the difference between poisonous and non-poisonous mushrooms. It also says that after eating a poisonous mushroom you may not become ill for many hours, that cooking outdoor mushrooms does not make them safe to eat, and that if someone has eaten mushrooms that were growing wild, you should not wait until the person feels sick to call (Ontario Poison Centre). Evidence: established.

In our reading, a dried, shrivelled, discoloured or old mushroom is even harder to judge than a fresh one, because the features an expert would look at may have changed. Our guide to why a name or a photo can’t clear a mushroom, and who to call explains the limits in detail. We do not offer identification tips.

When to call 911 rather than a poison centre: the Canadian Association for Poison Centres and Clinical Toxicology says that if the person is unconscious, not breathing or having a seizure, call 911 (CAPCC). The US Poison Control number, 1-800-222-1222, is for the US only; people elsewhere are told to use local procedures (Poison Control).

What is still not known?

• How fast psilocybin and psilocin break down in mushrooms under everyday conditions. The studies we found are few, small and done under laboratory or museum conditions.
• Why some specimens lose almost everything while others of similar age keep a good deal. The museum study authors say a purpose-built study would be needed to find out.
• Whether breakdown products formed over time have effects of their own. We found no study that answers this.
• How stable psilocybin is in edibles, capsules or other products. We found no published study, and products in an unregulated market are not tested to a standard.
• Whether mould on psilocybin mushrooms carries any risk beyond the general risks of mouldy food. We found no official source on this; Health Canada’s general advice is to avoid eating mouldy foods.

None of these gaps makes an old or mouldy mushroom safer. If someone may have eaten a mushroom that was unidentified, mouldy or not what they thought, the sources agree on the step to take: call a poison centre without waiting for symptoms. This article is general information, not medical advice.

Shroomverse sells mushroom products. This article is general information about what research and official food-safety and poison-centre sources say. It is not medical, legal or purchasing advice, it gives no storage or use instructions, and it does not encourage anyone to use drugs.