Grayanotoxin - Turkish mad honey and third-degree heart block

• also called andromedotoxin, acetylandromedol, and rhodotoxin by science people who can't seem to agree on one name (seriously, form a committee and get this sorted out, science people! I don't indirectly pay for some of your research for nothing, you know! I want clarity!)
• sublimely synthesized by a considerable number of plants belonging to the family Ericaceae, in particular, several of those of the genus Rhododendron
• is occasionally found in honey from Turkey (especially around the Black Sea) as a result of bees collecting nectar from certain species of Rhododendron that grow in the area
• this honey is called 'mad honey' ('deli bal' in Turkish) and people have been reporting that it makes them puke since 401 BCE
• mad honey is still a common source of food poisoning in Turkey, likely because it is also used as an alternative medicine AND there is an increasing demand for 'natural' products
• the locals can apparently tell when the honey is poisonous, as it causes a burning sensation in the throat following consumption
• binds to and inhibits the closing of (i.e. persistently activates) sodium channels, causing excitable tissues (muscle and nerve) to become overexcited (due to sustained depolarization)
• this can lead to things like muscle weakness, puking, excess sweating and salivating, and in cases of more severe poisoning, potentially life-ending heart problems like third-degree atrioventricular (AV) block as well as seizures and hypotension
  

Gunduz A, Turedi S, Uzun H, Topbas M. Mad honey poisoning. Am J Emerg Med. 2006 Sep;24(5):595-8.