Highlights.

  • Can a penicillin allergy also cause a mushroom allergy?

    There's not much evidence that penicillin allergies cause cross-reactivities with other molds or fungi, so it's considered unlikely that a penicillin allergy would be related to a mushroom allergy.

  • Is it safe to have magic mushrooms if you have a penicillin allergy?

    If your allergy to penicillin is mild (it doesn't cause hospitalization), then it is still safe to try psilocybin mushrooms. But if you have strong allergies to penicillin or to other mushroom varieties, it may not be safe.

  • Tips for trying magic mushrooms safely if you have a penicillin allergy?

    Have an experienced psychonaut present as a sober trip sitter, start with only a small dose, keep antihistamines around, and don't freak out at small reactions such as skin hives. Call emergency services if the allergy becomes an emergency.


We’ve received a number of questions regarding the use of magic mushrooms — AKA psilocybin mushrooms — and penicillin allergies.

It’s a valid question given that penicillin is a form of mold and magic mushrooms are a form of fungus — the two kinds of organisms are very similar. And there are many wondering whether or not it’s safe to use magic mushrooms if you also happen to have an allergy to penicillin.

We’ve got a very interesting topic on our hands because there are a few different kinds of sensitivities that can manifest between humans and fungi. There are:

  • penicillin allergies that are specific to penicillin but not all kinds of fungi
  • mushroom allergies that are vague and nonspecific
  • mushroom allergies that are specific


But where do these allergies overlap?

It’s important to remember that magic mushrooms do not contain penicillin. This means that having a penicillin allergy will not necessarily cause an allergic reaction to magic mushrooms.

But that doesn’t mean there isn't something else in the mushroom that you could have an allergic reaction to. This is an especially important factor to consider in those with overall mushroom allergies.

In this article, we’re investigating the difference between different mold allergies and sensitivities, and how someone with a penicillin allergy might safely go about using magic mushrooms.

Penicillin allergies, mushroom allergies, and mold sensitivities.

A painting of psychedelic magic mushrooms in outerspace surrounded by asteroids with faces on them.
@the.iron.swan

Penicillin is a kind of fungus or mold that happens to be beneficial to the human body — just like magic mushrooms!

When you think about it, there are a number of different fungi that humans have come to love. Even the good ol’ button mushroom is a healthy fungus for humans.

However, just like with many other foods, there are a small group of people for whom fungi trigger different kinds of allergies.

Penicillin allergy is considered the most common worldwide allergy, with around 8-12% of the population having a sensitivity reaction of varying degrees to penicillin. 

That being said, it’s uncommon for there to be penicillin cross-reactivity with other molds, even if they are respiratory ones. That is to say — just because a person is allergic to penicillin doesn’t mean they’ll have an allergic reaction to mushrooms, molds in cheeses such as blue cheese, or Psilocybin magic mushrooms.

In the modern context, “mushroom allergy” is widely accepted as an allergy to mushroom spores, with certain species being primary culprits. However, it’s primarily a respiratory reaction and isn’t thought to occur by eating magic mushrooms. Once upon a time, though, there was some scientific mention of non-specific mushroom allergies.

There have been reported reactions of gastrointestinal symptoms after oral ingestion of shiitake mushrooms and even reports of contact dermatitis after eating raw shiitake mushrooms. It seems from the research and anecdotal reports on forums such as Reddit that allergies to wild mushrooms or edible mushrooms manifest as itching, redness, hives, rash, and in the worst cases, anaphylaxis. 

Mushrooms are all composed of different things, all of which could theoretically cause an allergic reaction if the person has an allergy to any of those compounds. It’s worth noting that what makes psilocybin mushrooms “poisonous” is psilocybin itself! And if you’ve ever used magic mushrooms, you know what “magic mushroom poisoning” feels like!

So is it possible to be allergic to magic mushrooms if you have a penicillin allergy?

The short answer is yes.

It is possible. But not much more likely than anybody else having an allergy to magic mushrooms. As we just mentioned, it’s possible that some cross-reactivity takes place, but this has never been established for Psilocybin magic mushrooms.

There is still no science to back this up, but if a person has allergies to multiple kinds of fungi such as penicillin, shiitake, and porcini, then it’s more likely that they will have an allergy to something in magic mushrooms. But if the allergy is confined to penicillin, then the chances of being allergic to magic mushrooms exist, but they’re slim.

How can you safely use magic mushrooms if you have a penicillin allergy?

An illustration of a hand with different kinds of mushrooms growing out of the fingers and through the finger tips.
@charleysatelier

Now for the million-dollar question:

How can you safely use magic mushrooms if you’re allergic to penicillin?

If you’ve never tried magic mushrooms, then quite bluntly, you don’t know if you’re allergic to them. So before deciding if it’s safe to move along and try, ask yourself the following questions:

  • Do I ever get anaphylaxis to other foods such as nuts?
  • Do I ever have allergies to normal culinary mushrooms?
  • Is my penicillin allergy severe enough to send me to the hospital?


If you answered yes to any of those questions, it might not be safe for you to eat magic mushrooms. The risk might simply be too high. 

Otherwise, if you have a penicillin allergy that’s less severe but still want to create a safer environment for trying magic mushrooms, we have the following advice:

  • Don’t trip alone. Have a trip-sitter or someone around who isn’t taking magic mushrooms that can act in the event that you start having an allergic reaction. Make sure you give them all the information they need to be able to act if you require assistance.
  • Start with a small dose. Think about it — don't take a whopping dose of a potential allergen. Start with 1/2g to see your initial reactions.
  • Keep antihistamines around. If you use antihistamines when you get allergies, keep antihistamines around.
  • Keep your EpiPen around. If you have an EpiPen, make sure you know where it is. But remember, we don’t recommend trying magic mushrooms if you get anaphylaxis to any kind of mold or penicillin.
  • Accept the small possibility of dermatitis, rash, or itching — and don’t panic. However, notify someone immediately if there are any signs of tongue, lip, or throat swelling.

The difference between a sensitivity and an allergy: when is it an emergency?

A painting of a sloth hanging off vines attached to unusual looking magic mushrooms.
@kitmizeresart

There are varying degrees of penicillin allergy.

For example, some people experience swelling on the face or hands and feet while others might experience shortness of breath or swelling of the tongue. When a person is experiencing “sensitivity” symptoms, antihistamines are usually enough to reduce them. However, if a person is having “allergic” symptoms, they might begin to experience anaphylaxis.

If you experience swelling of any of the following, seek immediate medical care:

  • tongue
  • lips
  • throat


Any sign of swelling is a sign of an emergency and requires emergency medical care.

However, if you get hives or skin rashes as a reaction to magic mushrooms, it doesn’t necessarily mean that the reaction will escalate into anaphylaxis or require emergency medical care. This is why it’s important to have a trip sitter who will be able to identify these things. 

Overall, a simple penicillin allergy does not necessarily mean that a magic mushroom allergy exists — and in fact, it’s not all that likely. But given the small possibility of the two allergies overlapping, it’s just important to be prepared. And after reading this article, you should be equipped with all the preparation arsenal you need to make it a safe first experience.

Do you have a penicillin allergy and have you tried magic mushrooms? If yes, let us know in the comments what happened when you tried magic mushrooms. Your story will help lots of people in the local mushroom-using community to understand how to use mushrooms safely!

Related Reading: The Ultimate Magic Mushroom Dosage Guide

Related Reading: The Ultimate Guide to Magic Mushroom Microdosing

Related Reading: Microdose Cycling: What It Is, and Why You Should Be Doing It

Related Reading: The Benefits of Microdosing Psilocybin — Without the Fluff

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