# Brown roll-rim (Paxillus involutus)

**Paxillus involutus**

**Known today as.** A common brown mushroom with a rolled rim, of birch woods.

Kind: Fungus  
Poisoning: Paxillus syndrome (immune haemolysis) (https://thethinkingpress.org/materia-medica/poisons/paxillus)  
Toxic: yes

> **Caution.** Poisonous; the danger comes with repeated meals.

## What was it used for?

Once widely eaten in eastern Europe.

## What does modern science say?

Repeated eating can set off an immune reaction that destroys the red blood cells and can injure the kidneys.

## Pharmacognosy and toxicology

- **involutin**: the browning pigment
- **unknown antigen**: the cause of the haemolysis

**Mechanism.** An antigen in the mushroom raises antibodies that, on a later meal, attach to the red cells and destroy them.

**Dose.** Any meal after sensitisation; years of eating it may precede the reaction.

**Standing.** None; guidebooks firmly warned against eating it only from 1990.

## What lore surrounds it?

The German mycologist Julius Schäffer died after eating it in 1944; others have eaten it for years without harm before it struck.

## Sources

- Wikipedia, “Paxillus involutus,” en.wikipedia.org (read 2 October 2026).

---

*Brown roll-rim.* In *Materia Medica*, edited by B. C. P. Statema. Version 1, revised 2026-10-03. The Thinking Press. https://thethinkingpress.org/materia-medica/brown-roll-rim

Historical description, not medical advice.