Solanaceae
Capsicum annuum
Chilli · Cayenne · Paprika · Bell pepper
- Part used
- fruit
- Native range
- Mexico and Central America; cultivated worldwide
- Morphology
- An annual or short-lived perennial to a metre with white flowers and fruit of enormous variety — the species covers bell peppers, cayenne, jalapeno and paprika, all one species differing by cultivar.
What is in it
Evidence
Topical capsaicin has genuine evidence and is a registered medicine for neuropathic pain and osteoarthritis, working by depleting substance P from sensory nerve endings. High-concentration capsaicin patches are used in specialist pain clinics.
Safety
Culinary use is benign for most people and aggravates reflux and some gastrointestinal conditions. Concentrated capsaicin is a severe irritant to eyes and mucous membranes — it is the active agent in pepper spray. Extremely hot cultivars have caused oesophageal rupture and thunderclap headache in eating-challenge settings.
Interactions: May affect absorption of drugs taken concurrently; Theoretical additive with anticoagulants
Regulatory: Permitted as a food. Topical capsaicin is a registered medicine at controlled concentrations.
How the traditions classify it
Three systems, rating the same plant. Where they disagree, none of them is correcting the others — they are separate frameworks that arrived at their categories independently.
Historical use
Domesticated in Mesoamerica at least six thousand years ago and used as food and medicine. Carried worldwide after 1492 and absorbed into the medical systems of Asia and Africa within a century — an unusually well-documented case of a tradition acquiring a new plant.
Recorded as history and attributed where possible. Long use establishes that a plant was widely used, not that it worked, and not that it was safe.
Worth knowing
Capsaicin does not make anything hot. It binds TRPV1, the receptor that detects actual heat and tissue damage, and the brain reports burning because the signal is identical to the one a burn produces. The reverse of menthol on TRPM8, and between them they explain how four unconnected traditions built medicine on hot and cold — the categories track real receptor pharmacology.
Its clinical use runs on the same mechanism in reverse. Sustained capsaicin exposure depletes substance P from sensory nerve endings and eventually defunctionalises them, which is why a high-concentration patch can reduce neuropathic pain for weeks. The traditional counter-irritant use of hot plants was pointing at something real.
The species is also a lesson in how fast a materia medica can absorb a novelty. Chilli reached Asia after 1492 and was fully classified within Chinese, Ayurvedic and Unani frameworks inside a century — traditions that present themselves as ancient and unchanging assimilating a new plant in a few generations.
Nomenclature verified against GBIF backbone taxonomy.