Croton oil 2026-10-31
The oil expressed from the seeds of Croton tiglium; a strongly irritant historical medicinal material.
Mustard 2026-10-31
Mustard seed materials used in historical preparations. Moistening crushed black-mustard seeds generates an irritant volatile product containing allyl isothiocyanate; the volatile product differs from the fixed seed oil.
The required sequence is fresh flowers; sliced and dried bulb; unexpanded petals; heartwood; seeds; expressed seed fat; expressed seed oil; and fresh and dried root. The plant organ, its state, and the actual official material must all be specified.
- Sambucus nigra: fresh flowers. The official article is Sambuci flores, elder flowers, gathered from the native plant. The flower stalks are separated when making elder-flower water; the preparation also allows an equivalent quantity of flowers preserved fresh with common salt. Neither elder berries nor elder bark answers the botanical part asked here.[ref]British Pharmacopoeia by the General Medical Council (1867). “Sambuci flores”, p. 274; “Aqua sambuci”, p. 45
- Squill: the sliced and dried bulb. The historical botanical source is Urginea scilla, also identified there as Scilla maritima. The medicinal slices consist of the fleshy bulb scales; this is an underground shoot structure, not a root. The official article is Scilla.[ref]British Pharmacopoeia by the General Medical Council (1867). “Scilla”, pp. 279–280
- Rosa gallica: the fresh and dried unexpanded petals. These are Rosæ gallicæ petala, the red-rose material. “Unexpanded” refers to collection before the flower has opened fully. The petals must be distinguished from the rose hip used for a different official preparation.[ref]British Pharmacopoeia by the General Medical Council (1867). “Rosæ gallicæ petala”, red-rose monograph
- Pterocarpus santalinus: the sliced or rasped heartwood. This is Pterocarpi lignum, red sandalwood. The answer is the wood, rather than bark or the exudate known as kino. Botanical relationship between two medicinal materials does not make their official definitions interchangeable.[ref]British Pharmacopoeia by the General Medical Council (1867). “Pterocarpi lignum”, p. 261
- Physostigma venenosum: the seed. Physostigmatis faba, the Calabar bean, is botanically a seed, not the entire pod. Its two large cotyledons lie inside a hard seed coat. The official alcoholic extract is made from the powdered seed.[ref]British Pharmacopoeia by the General Medical Council (1867). “Physostigmatis faba”, pp. 233–234; “Extractum physostigmatis”, p. 126
- Theobroma cacao: the concrete oil obtained by expression and heat from the ground seeds. The official article is Oleum theobromæ, cocoa butter. Naming the seed gives its source organ, but omits the important fact that the official pharmaceutical material is the separated fat. It is distinct from coconut oil.[ref]British Pharmacopoeia by the General Medical Council (1867). “Oleum theobromæ”, p. 229
- Croton tiglium: the oil expressed from the seeds. The official material is Oleum crotonis, croton oil, rather than the whole plant or an unspecified leaf preparation. The seeds are its source; the expressed oil is the article used in the official formulations.[ref]British Pharmacopoeia by the General Medical Council (1867). “Oleum crotonis”, p. 222
- Taraxacum officinale: the fresh and dried root. The official article is Taraxaci radix, dandelion root, called Taraxacum dens leonis in the 1867 standard, gathered between September and February from British meadows and pastures. The collection season and fresh/dried distinction belong to the historical standard; the answer is not the leaves or flowers.[ref]British Pharmacopoeia by the General Medical Council (1867). “Taraxaci radix”, p. 317
The names in the paper sometimes use the shorter terminology of the first British Pharmacopoeia, whereas the 1867 edition explicitly renamed many entries to identify the medicinal organ. Its alteration list, for example, maps Sambucus to Sambuci flores, Pterocarpus to Pterocarpi lignum, and Taraxacum to Taraxaci radix.[ref]
British Pharmacopoeia by the General Medical Council (1867). “Articles the names of which have been altered”, pp. xix–xxi
That is a nomenclature change, not permission to choose any part of the named plant.Ordinary cantharides blisters owe their activity to cantharidin; other blistering methods act through different chemical irritants or through physical injury. There is no single substance common to every way of raising a blister.
In the standard historical preparations, the dried blister beetle supplies cantharidin. A plaster, blistering paper, blistering liquid, or cantharides vinegar is a different vehicle for delivering the same vesicant to the skin. Extracting the beetle into a liquid does not make the solvent the specific active principle. The 1867 British Pharmacopoeia includes Emplastrum cantharidis, Charta epispastica, Liquor epispasticus and Acetum cantharidis.[ref]
British Pharmacopoeia by the General Medical Council (1867). “Cantharis”; “Acetum cantharidis”; “Charta epispastica”; “Emplastrum cantharidis”; “Liquor epispasticus”
Other historical means need separate explanations. Moist mustard develops an irritant volatile product, principally allyl isothiocyanate from black mustard; its usual intended effect is reddening, with prolonged exposure capable of more destructive injury. This differs from the fixed mustard seed oil: the irritant volatile product develops after moistening the powdered seeds.[ref]
British Pharmacopoeia by the General Medical Council (1867). “Sinapis” and “Oleum sinapis”; mustard seed preparations and production of the volatile oil
Strong Ammonia acts as an alkaline irritant. Croton oil can produce an inflammatory and pustular eruption, which is not the same lesion as a clean cantharides blister. A sufficiently hot object or hot liquid raises a blister through thermal damage, without a medicinal active molecule. These differences matter because erythema, a fluid-filled blister, a pustule, and tissue destruction are not interchangeable endpoints.For cantharidin, the modern tissue explanation involves loss of adhesion between epidermal cells, including disruption of desmosomes, with separation within the epidermis and accumulation of fluid. The blister is therefore a local lesion of cell adhesion accompanied by inflammation, rather than a pocket containing disease drawn from a remote organ. The FDA review describes this acantholysis and distinguishes it from the incompletely understood mechanism of clinical benefit in a particular modern indication.[ref]
- Counterirritation. A new superficial irritation was believed to relieve a deeper painful or inflamed part by altering nervous activity and the distribution of blood. A physiologically intelligible component is that input from sensory nerves can change pain processing and reflex output. That does not establish the stronger historical claim that creating an artificial inflammation cures an unrelated internal inflammation.
- Serous drainage or “depletion”. Fluid escaping from the raised blister was thought to remove fluid from the circulation and reduce local fullness. Fluid does indeed leave damaged blood vessels and collect in the blister, but the observation alone does not demonstrate beneficial selective removal of a disease-producing substance. Maintaining a draining sore was a historical practice, not a consequence required by current physiology.
Thus the demonstrable processes are local injury, inflammation, fluid exudation, and sensory stimulation; the broad historical claims of remote benefit require separate evidence. Current approved topical cantharidin use for molluscum contagiosum does not validate nineteenth-century blistering for diseases of internal organs. The modern label explicitly states that the mechanism of action in molluscum contagiosum is unknown and documents local skin reactions.[ref]