Previously used as a treatment for tapeworm. No longer used due to toxic side effects.

Podlech, D. (1996). Herbs & Healing Plants of Britain & Europe, Collins p.196

Active ingredients = Phloroglucine derivatives, tanins, bitters.

Podlech, D. (1996). Herbs & Healing Plants of Britain & Europe, Collins p.196

Neurogenic Vision Loss Plant Toxicities "In England, ingestion of the rhizomes of male fern (Dryopteris filix-mas) by cattle has been associated with permanent or, more frequently, transient blindness. Blindness may be the primary presenting sign, although drowsiness, weakness, malaise, and constipation also occur. Retinal ganglion cells and optic nerve fibers are destroyed, and on ophthalmoscopy, variable amounts of papilledema and peripapillary hemorrhages are observed initially (thus necessitating differentiation from hypovitaminosis A). In advanced cases, optic nerve head atrophy and retinal vascular attenuation are noted" [Paul Miller].

Paul E. Miller, in Food Animal Practice (Fifth Edition), 2009 https://www.sciencedirect.com/topics/agricultural-and-biological-sciences/dryopteris-filix-mas

Toxic due to presence of phloroglucinol. Severe effects in humans and domestic animals after swallowing

Professor Anthony Dayan, 2022

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