Bees produce honey after collecting pollen and nectar from plants. When these plants contain grayanotoxin the honey so produced will also contain these neurotoxins.
Consumption of this honey can cause poisoning or some form of intoxication, resulting in psychedelic highs. That is the reason this honey is called Mad Honey. It is a honey that is produced in Nepal and Turkey, where it sees wide use as a recreational drug and as part of traditional medicine.
Certain doses of the honey do produce recreational effects but as the concentration of grayanotoxins is not controlled it is not possible to find doses of the honey that would be safe. As a result, cases of poisoning through the use of this honey are known to occur. The honey can cause nausea, vomiting, blurred vision, salivation, sweating, and seizures, besides other symptoms. The effects mostly concern the cardiovascular system.