Omphalotus japonicus (Tsukiyotake) — Poisonous Mushroom

Korean name: 화경버섯

A mushroom with the unusual ability to glow faintly in the dark. It resembles shiitake and oyster mushrooms, so poisonings from mix-ups are frequent.

Key facts

• Category: Poisonous mushroom
• Toxicity: Poisonous — do not eat. Keep children and pets away.
• Native to: Korea, Japan
• Traits: Bioluminescent, Edible look-alike, Shiitake look-alike, Oyster look-alike, GI toxin
• Also known as: Lampteromyces japonicus, Tsukiyotake, Moonlight mushroom

Toxicity, identification & first aid

• Toxic symptoms: Contains illudin toxins. Nausea, vomiting, stomach pain and diarrhea within 30 minutes to 2 hours; severe cases risk dehydration.
• Appearance: Cap 5–20 cm, yellow-brown to orange-brown with crowded gills. Glows faintly in the dark.
• Where found: At the base or roots of dead broadleaf trees (oak, chestnut), growing in clusters.
• Season: Autumn (September–November)
• Look-alike warning: Shiitake (grows singly or in small numbers) and oyster mushrooms (grey-white).
• Emergency action: Call emergency services (119 in Korea) and go to the ER immediately. Watch for dehydration from vomiting and diarrhea; fluids may be needed.

Common questions

Can you eat Omphalotus japonicus?

No. Omphalotus japonicus is poisonous. Contains illudin toxins. Nausea, vomiting, stomach pain and diarrhea within 30 minutes to 2 hours; severe cases risk dehydration.

What does Omphalotus japonicus look like and where does it grow?

Cap 5–20 cm, yellow-brown to orange-brown with crowded gills. Glows faintly in the dark. At the base or roots of dead broadleaf trees (oak, chestnut), growing in clusters. Autumn (September–November)

What can Omphalotus japonicus be mistaken for?

Shiitake (grows singly or in small numbers) and oyster mushrooms (grey-white).

What should you do if someone eats Omphalotus japonicus?

Call emergency services (119 in Korea) and go to the ER immediately. Watch for dehydration from vomiting and diarrhea; fluids may be needed.