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Rhododendron and azalea: toxicity, first aid and care
Rhododendron and azalea (Rhododendron spp.): toxic for cats, toxic for dogs, toxic for small children. The toxic principle, the signs, what to do, and how to grow it.
Cats: ToxicDogs: ToxicChildren: Toxic
Also sold as: Azalea, alpenrose, rododendron.
This is a reference table, not a diagnosis and not veterinary or medical advice. It cannot tell you how much of a plant matters for a particular child or a particular animal — that depends on body weight, on the part eaten and on how long ago. If a person or an animal has eaten part of a plant, phone the poison information centre or a clinician; do not wait for symptoms, and do not make anyone vomit unless you are told to.
What is in it
Toxic principle: Grayanotoxins — Alkaloids and other systemic poisons.
Grayanotoxins hold sodium channels open in nerve and muscle, so the effect runs from the gut to the heart. Leaves, flowers and nectar carry them. This is the source of the old accounts of "mad honey": honey made predominantly from Rhododendron nectar can carry enough grayanotoxin to poison the person who eats it, which is a real and still-reported phenomenon in some regions.
What it looks like when it goes wrong
Drooling and repeated vomiting, then weakness, wobbliness, a slow heart rate and low blood pressure. Dogs that browse a hedge are the usual veterinary case in this region; a mouthful of leaves is enough to make a small dog properly ill.
What to do
Phone a veterinary clinic or the poison centre. Most cases recover with supportive care, but the cardiac effects mean an animal that has eaten a real quantity should be seen rather than watched at home.
| Country | Poison information centre | Number | Hours |
|---|---|---|---|
| Estonia | Mürgistusteabekeskus (Health Board) | 16662 | Round the clock; 112 for an emergency |
| Finland | Myrkytystietokeskus (HUS) | 0800 147 111 | Free, round the clock |
| Latvia | Saindēšanās un zāļu informācijas centrs | 67042473 | Round the clock |
| Sweden | Giftinformationscentralen | 010-456 67 00 | Non-urgent advice; 112 in an emergency |
| Norway | Giftinformasjonen | 22 59 13 00 | Round the clock |
| Denmark | Giftlinjen (Bispebjerg Hospital) | 82 12 12 12 | Round the clock |
Anywhere in the European Union, 112 reaches emergency services and can put you through. Lithuania's poison information bureau (Apsinuodijimų kontrolės ir informacijos biuras) publishes its own round-the-clock line; if you do not have it to hand, use 112. For an animal, your own veterinary clinic or its out-of-hours service is the first call — human poison centres do not advise on animals in every country.
How to grow it
| Condition | What it wants |
|---|---|
| Light | Dappled shade; scorches in hot afternoon sun |
| Water | Consistently moist, and rainwater rather than hard tap water |
| Temperature | Hardy in the region if planted out of drying spring wind |
They demand acid soil, which much of the Baltic region does not naturally provide, so they are usually grown in a prepared ericaceous bed or a large pot of ericaceous compost. Mulch with pine bark or needles, never lime, and do not let the rootball dry out in late summer — next year's buds are being made then.
What it gets confused with
The dwarf pot azaleas sold flowering in midwinter are the same genus and the same chemistry, and they end up on coffee tables at exactly cat height. They are also, unlike the garden shrubs, indoors all winter with a bored animal — which is why the indoor plant is the one that shows up in poison-centre calls.
A plant that is not on the toxic lists
If you are deciding what to keep in a home with a cat, a dog or a small child, this one fills a similar role and is not flagged by the veterinary services.
Others that work the same way
Alkaloids and other systemic poisons — these behave alike, and what you would do about them is alike too.
Autumn crocus
Colchicine
Castor bean
Ricin (in the seed)
Deadly nightshade and bittersweet
Tropane alkaloids (atropine, hyoscyamine, scopolamine); solanine in Solanum
Monkshood
Aconitine alkaloids
Sago palm
Cycasin and related azoxyglycosides
True lily and daylily
Unidentified nephrotoxin (cats only)
Source: ASPCA Animal Poison Control — toxic and non-toxic plants · checked 2026-09-06
Care guidance is standard horticultural practice for a cool-temperate northern climate. Poison-centre numbers are listed on the hub page and are worth confirming against your own country's health service.
Frequently asked questions
Is rhododendron toxic to cats?
The veterinary lists rate it "toxic" for cats and "toxic" for dogs. The toxic principle is grayanotoxins. Grayanotoxins hold sodium channels open in nerve and muscle, so the effect runs from the gut to the heart. Leaves, flowers and nectar carry them.
What should I do if my dog eats rhododendron?
Phone a veterinary clinic or the poison centre. Most cases recover with supportive care, but the cardiac effects mean an animal that has eaten a real quantity should be seen rather than watched at home.
Is rhododendron dangerous for a small child?
The verdict for a child who chews or swallows part of it is "toxic". Drooling and repeated vomiting, then weakness, wobbliness, a slow heart rate and low blood pressure.
How do you care for rhododendron?
Light: Dappled shade; scorches in hot afternoon sun. Water: Consistently moist, and rainwater rather than hard tap water. Temperature: Hardy in the region if planted out of drying spring wind. They demand acid soil, which much of the Baltic region does not naturally provide, so they are usually grown in a prepared ericaceous bed or a large pot of ericaceous compost.
What is rhododendron confused with?
The dwarf pot azaleas sold flowering in midwinter are the same genus and the same chemistry, and they end up on coffee tables at exactly cat height. They are also, unlike the garden shrubs, indoors all winter with a bored animal — which is why the indoor plant is the one that shows up in poison-centre calls.
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