Grayanotoxin: The Compound Behind Mad Honey

Short answer: Grayanotoxins are natural compounds made by rhododendron and a few related plants in the heath family. They are what make mad honey different from regular honey. They work by holding sodium channels in nerve and heart cells open, which can slow the heart and lower blood pressure. Bees carry them from rhododendron nectar into the honey.

What Grayanotoxin Is

Grayanotoxins are diterpenes, a family of plant compounds built on a 20-carbon frame. They are not alkaloids and they have no relation to the substances found on a standard drug panel.

There is more than one. Researchers have described many forms, and a 2018 review in RSC Advances counts 18 known grayanotoxin types, not all of them toxic (Ullah et al., 2018). Grayanotoxin I and grayanotoxin III are the ones most tied to mad honey effects.

• Grayanotoxin I is the main driver of heart effects, acting on the heart's natural pacemaker and the conduction between upper and lower chambers.
• Grayanotoxin II is considered less toxic.
• Grayanotoxin III is linked to rhythm disturbances and is the form most often measured in honey studies.

The Mad Honey Plant: Rhododendron

When people search for "the mad honey plant," the answer is rhododendron. More precisely, a handful of rhododendron species whose nectar carries high levels of grayanotoxin.

A 2012 review in Cardiovascular Toxicology lists the plant groups that make grayanotoxins: Rhododendron, Pieris, Agarista and Kalmia, all in the family Ericaceae (Jansen et al., 2012). Within rhododendron, the species named most often in honey research include:

• Rhododendron ponticum, common in Turkey's Black Sea region
• Rhododendron luteum, a yellow azalea of the same region
• Rhododendron flavum and Rhododendron simsii, also listed in the 2018 review

In Nepal, Himalayan rhododendron species on high slopes play the same role. For the basics of the honey itself, read What Is Mad Honey? Rhododendron Honey Explained.

Rhododendron in Your Yard

Rhododendrons and azaleas are common garden shrubs in the US. Many of them contain grayanotoxins in their leaves, flowers and nectar. Mountain laurel (Kalmia latifolia) and western azalea are also on the list.

That does not mean every garden shrub is dangerous to walk past. It does mean the leaves and flowers should not be eaten, and that pets and grazing animals can be poisoned by chewing them. Honey from home hives near big rhododendron plantings is usually diluted by other flowers, but not always.

How Grayanotoxin Works in the Body

Every nerve and muscle cell uses sodium channels to fire. A channel opens, sodium rushes in, the cell fires, and the channel shuts again.

Grayanotoxins bind to these channels and stop them from shutting the way they should. The cell stays partly switched on. The 2012 review describes binding at a specific site on voltage-gated sodium channels, which keeps them active.

The biggest effect lands on the vagus nerve, which acts like a brake on the heart. When that brake is pushed harder, the heart slows and blood vessels relax. The result:

• A slow heart rate (bradycardia)
• Low blood pressure (hypotension)
• Dizziness and fainting
• In more serious cases, heart block, where signals between heart chambers are delayed or stopped

The same action on nerves explains tingling, sweating, salivation and nausea. For what people describe at small amounts, read Mad Honey Effects: What People Report and Why.

Why the Dose Matters

A 2007 review in Food and Chemical Toxicology describes the effects of grayanotoxin as dose dependent (Koca and Koca, 2007). At low exposure people report dizziness, weakness, sweating, nausea and vomiting, usually needing only monitoring. At higher exposure the heart effects become serious, including complete heart block.

The hard part is that the amount of grayanotoxin in a spoonful is not fixed. It depends on how much nectar came from toxic species that season. That is why mad honey is taken in small amounts and why small jar sizes make sense.

How Long It Stays in the Body

Grayanotoxins are cleared fairly quickly. The 2018 review notes that they are usually metabolized and excreted within about 24 hours, which is why most hospital cases resolve within a day with fluids and atropine, a drug that blocks the vagus nerve's braking effect.

One thing that surprises people: grayanotoxin does not show up on a routine drug test. Labs can measure it with specialized methods, but standard screens do not look for it. We go deeper in Mad Honey, Grayanotoxin and the ECG Pattern.

Grayanotoxin and Honey Quality

Because the compound is what separates mad honey from regular honey, it is also what people point to when they ask whether a jar is real. Color and taste offer clues, but only lab methods can actually measure grayanotoxin content.

We sell Himalayan mad honey in 25g jars. See the product page for sourcing details. The standard 25g jar is the place to start.

Who Should Avoid Grayanotoxin

Because of its action on the heart, skip mad honey if you have a heart condition, low blood pressure or a slow heart rate, take blood pressure or heart rhythm medicine, are pregnant or nursing, or are under 21. If you feel faint, dizzy, short of breath or notice a slow heartbeat after eating it, get medical care and tell them what you ate.

FAQ

What plant does mad honey come from?

Rhododendron. Specific species with high grayanotoxin nectar, like Rhododendron ponticum and Rhododendron luteum in Turkey and Himalayan species in Nepal, give mad honey its character.

Is grayanotoxin the same as a drug?

No. It is a natural plant diterpene. It is not a controlled substance and is chemically unrelated to the drugs on a standard drug panel.

Are garden rhododendrons poisonous?

Many contain grayanotoxins in their leaves, flowers and nectar. Do not eat any part of the plant, and keep pets and livestock from chewing on it.

These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease. Adults 21+.