Common ink cap

Statema, B. C. P.

Fungus

Common ink cap

Coprinopsis atramentaria

Known today as: A grey mushroom that dissolves into black ink as it ages.
Kind: Fungus
Constituents: coprine
Poisoning: Coprine and alcohol
In other databases: GBIF search · Wikidata search

Revised October 3, 2026: Checked against its sources, each read in full, in part, or in its abstract. Version 1, first published September 25, 2026.

Caution. Poisonous with alcohol, even days later.

Common ink cap: what was it used for?

Its black liquid was once used as ink.

Common ink cap: what does modern science say?

Its coprine blocks the breakdown of alcohol, as the drug disulfiram does, so that a drink taken days after eating it brings flushing, nausea, and a racing heart.

Common ink cap: is it poisonous?

Yes, in some form or dose. Poisonous with alcohol, even days later. Its poisoning is coprine and alcohol: Minutes after drinking alcohol, up to three days after the meal. Historical description, not medical advice; in a poisoning, call a poison centre.

Pharmacognosy & Toxicology

Constituents

coprine

Mechanism

Coprine’s metabolite blocks aldehyde dehydrogenase, so alcohol builds up as acetaldehyde.

Toxic dose

Any amount, with alcohol, within about three days.

Syndrome

Coprine and alcohol

Standing

Edible without alcohol.

Constituent names open the compound’s record at PubChem, and “ChEMBL” beside a name opens its record at ChEMBL, the European Bioinformatics Institute’s database of bioactive molecules. Where a mechanism line was checked against ChEMBL (ChEMBL 37, read 1 October 2026), the check is shown with the measured value and its source paper, or says plainly that nothing has been measured. Doses are as the references give them, for description only; this is not medical advice. Each source carries the result of its check against Crossref, PubMed, or the authority’s page: see Verification.

Common ink cap: what lore surrounds it?

“Tippler’s bane”: harmless on its own, it turns cruel with wine.

In Their Own Words

Cooke says that when this mushroom is fully expanded and melting away in inky drops, it is fit for nothing but to replenish the inkstand.

“When fully expanded and melting away in inky drops, it is unfit for anything except to replenish the inkstand.”

M. C. Cooke, A Plain and Easy Account of British Fungi, Coprinus atramentarius, p. 52. London: Robert Hardwicke, 192, Piccadilly, 1862 (Internet Archive OCR text). The text, read in part

Badham says Agaricus atramentarius is as good for ketchup as for the use to which its juices are more commonly put, the making of ink.

“…as good for ketchup as for that purpose to which its juices are more commonly put, viz. — for making ink”

Charles David Badham, M.D., A Treatise on the Esculent Funguses of England, Modes of Distinguishing, p. 37. London: Reeve, Brothers, King William Street, Strand, 1847 (Internet Archive OCR text). The text, read in part

Each passage is quoted from the text named, which the press fetched and read, and was checked word for word against a fresh copy of it; the link opens that copy. Passages are given as printed, without the editors’ footnote numbers, and with words broken across lines joined.

Sources

Wikipedia, “Coprinopsis atramentaria,” en.wikipedia.org (read 2 October 2026). Read in full · the text read
Wikipedia, “Coprine,” en.wikipedia.org (read 2 October 2026). Read in full · the text read

Verification

Checked

October 1, 2026, and October 3, 2026

Passes

Every sentence read against its sources, in the pass over the remaining 343 entries
The Standing line checked against the authority it names (EMA, WHO, FDA, CITES, Commission E)
Every dated or regulatory claim checked by category across the database
Every source read, in full, in part, or in its abstract, and every sentence checked against what was read (October 3, 2026)

Sources

2 cited: 2 read in full.

Corrections

None were needed.

What was checked, how, and what was found is set out on the Verification page. A checked source is one whose record was found; it does not make the entry medical advice.

Cite This Entry

Version 1 · first published September 25, 2026 · last revised October 3, 2026

Chicago: “Common ink cap.” In Materia Medica, edited by B. C. P. Statema. Version 1. The Thinking Press, 2026–. Last modified October 3, 2026. https://thethinkingpress.org/materia-medica/common-ink-cap.
MLA: “Common ink cap.” Materia Medica, edited by B. C. P. Statema, version 1, The Thinking Press, 3 Oct. 2026, thethinkingpress.org/materia-medica/common-ink-cap. Accessed 8 Oct. 2026.
APA: Common ink cap. (2026, October 3). In B. C. P. Statema (Ed.), Materia medica (Version 1). The Thinking Press. Retrieved October 8, 2026, from https://thethinkingpress.org/materia-medica/common-ink-cap

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