Is Rhododendron toxic? Beware of child, cat and dog!

• Several poisons in rhododendrons
• How the poison works
• Poison in the parts of plants

Rhododendron is poisonous, in all parts and with several poisons, but not a single person has died of a rhododendron. The poison is therefore not necessarily a reason to pick out the newly planted rhododendron again; a little caution in dealing is already appropriate.

The rhododendron even has several poisons to offer. With them, warriors were poisoned in ancient times, but not deadly, that had to get the opponents themselves. Here is a brief overview of the poison in Rhododendron:

Several poisons in rhododendrons

Rhododendrons have developed a number of diterpenes (phytochemicals), which should probably scare off predators, but are anything but healthy for humans and their pets:

• The grayanotoxin group with grayanotoxin I to XXI
  • Grayanotoxin I is also known as acetylandromedol or andromedotoxin
  • Grayanotoxin II as Andromedenol,
  • Grayanotoxin III as Andromedol
  • Grayanotoxins IV to XXI are still under investigation
• The same applies to the remaining toxins found in rhododendron
  • Rhodajaponin I to VII,
  • Grayanoside A,
  • Pieroside A,
  • Rhodomolines, rhodomolleines and rhodomosides

Nothing is known so well and that is also evident in the publications on the toxins in rhododendron.

How the poison works

At least we know from investigations of those affected how the poison of Rhododendron works:

• Target organs are mucous membrane of the gastrointestinal tract, heart, skeletal muscle, peripheral and central nervous system
• The toxins work by binding to specific cell channels and hindering their normal work
• They cause a long-lasting depolarization of the cells, which disturbs the transmitter release
• In addition, the central vomiting center is stimulated via the vagus nerve

What this can do now, can only be summarized here:

• Symptoms are initially abdominal pain, nausea, diarrhea, increased salivation, nausea
• At higher dose you may experience respiratory disorders, seizures and (severe) cardiac arrhythmias
• In severe poisoning, the heart activity may slow down, the pulse is weak
• At some point up to the coma and death by respiratory arrest, so far probably not observed in humans
• With domestic and grazing animals already, the smaller or weaker, the faster Rhododendron can be dangerous

As I said, just an overview, but if anyone in your area should manage to consume plant parts of a rhododendron in appreciable quantities, you should always call the Poison Control Center.

Tip: As a first aid measure in case of suspected rhododendron poisoning, plenty of hydration is recommended. Thereafter / at the same time the hospital / a doctor should be visited, there is given medical coal or another poison removal carried out, as antidote atropine works.

Poison in the parts of plants

All plant parts contain toxic ingredients in different proportions. Root, shoots, leaves, flowers, fruits, nectar, pollen, all not meant to be tasted by children, to be nibbled on by pets, to be processed by hobby gardeners without gloves.

No one knows how much poison sits in a particular rhododendron:

• Of the approximately 1, 000 species, only a few have been studied
• Of the approximately 20, 000 breeding forms, even fewer percentages
• One only knows that rhododendrons contain very different amounts of toxin
• There should also be varieties in which no toxins were detected at all
• But they do not tell us, because it could be different at the next plant
• Against whom and under which environmental conditions the toxins were / are developed, is also still unexplored

For this reason, the Poison Information Center North points out that it is not possible for it to make specific statements about the toxin of individual rhododendron varieties.

Other source name rhododendron varieties:

• Rhododendron catawbiense (highly toxic)
• Rhododendron luteum (highly toxic)
• Rhododendron simsii (highly toxic)
• Rhododendron ponticum
• Rhododendron occidentale
• Rhododendron macrophyllum
• Rhododendron albiflorum
• Rhododendrum arboreum
• Rhodododendron campanulatum,

certainly no reason to taste other than these rhododendrons.

But also no cause for panic: The GIZ North has kept records, in his (not exactly small) catchment area there were 208 calls for Rhododendron in the recording period:

• 4 x gastrointestinal discomfort and fever, but not solely by rhododendron
• 32x mild gastrointestinal symptoms and / or fever, restlessness, muscle tremors, headache, burning in the throat,
• 161 x no symptoms,
• 11 x too unclear information, but it is good.

The GIZ North confirms "no increased toxicity of rhododendrons compared to other ornamental plants", but advises, as a precaution, not to plant rhododendrons in places that serve children as a place to stay and play.

Tip: If children and pets are to be carefree in the garden with no worries, avoid not only rhododendrons, but plenty of heather plants (and other plants).