This section is from the book "Botanic Drugs Their Materia Medica, Pharmacology and Therapeutics", by Thomas S. Blair. Also available from Amazon: Botanic Drugs, Their Materia Medica, Pharmacology and Therapeutics.
Fish Berries. Similar to strychnine in action, though less tetanic. Picrotoxin is derived from it. There is some justification for 1-60 grain doses in paralysis of the sphincters, in paralysis agitans, and in vaso-motor derangements during the menopause. It was formerly much used for controlling night sweats. These internal uses are losing out in professional esteem; but an ointment (ten grains to the ounce) is highly effective in killing pediculi. Never apply it to abraded surfaces. The tr. is used in full strength to kill body lice. Nevertheless it is a dangerous agent, and a 25% solution trichlor-ethylene in petrolatum is much safer for application to the human body. This is the maximum strength, as low as 2% trichlorethylene in soapy water killing lice and nits in 30 minutes.
In my opinion, picrotoxin should rarely, if ever, be used. Ignatia serves its every purpose except the killing of parasites and its debatable value for controlling night sweats, and ignatia is safe in employment. Cocculus is too irregularly toxic to be safe in physiologic dosage, and its reputation was built up largely by the Homeopathic employment in small doses.