Rhododendron Poisoning


It is not hard to appreciate these popular perennial shrubs that bloom bright and bold flowers in shades of purple, pink, orange, yellow and white, but rhododendrons are poisonous if ingested. Rhododendron species are classified as wood shrubs that, depending on the variety, may be deciduous, semi-evergreen or evergreen. According to the University of Illinois at Urbana-Champaign, there are approximately 800 species of rhododendrons worldwide.


Rhododendrons are common houseplants and landscaping shrubs, and they are found in natural settings throughout the United States. All parts of the rhododendron plant are poisonous. According to the University of Pennsylvania, grayanotoxins, or andromedotoxins, are the toxic agents naturally found in rhododendrons. Grayanotoxins are diterpenoid compounds, which are water-soluble, and they are found in the flower nectar and leaves of the rhododendron plant.

How It Works

Grayanotoxins affect the body through internal poisoning at the cellular level. They change the sodium channels in the cell membranes, which depolarizes the cells. Calcium then easily enters the cells and causes stronger muscle contractions—a positive inotropic effect, according to the University of Pennsylvania.

Signs of Rhododendron Poisoning

Ingestion of rhododendron plant or flower parts or rhododendron nectar may result in burning of the mouth, increased salivation, vomiting, diarrhea, impaired vision, muscle weakness, slower heart rate, lower blood pressure and other cardiovascular conditions, and gradual paralysis of the extremities, according to North Carolina State University. Severe poisoning can lead to a coma or death. According to the University of Illinois at Urbana-Champaign, signs of toxicity are often seen within six hours of ingestion.


The first lines of treatment for rhododendron poisoning include detoxifying the body of the poison and supporting the body to overcome the poisoning. Detoxification may include force vomiting, or emesis, and according to the University of Pennsylvania, activated charcoal is effective for detoxifying the body of the poison. Supportive therapy may include supporting the breathing and restoring fluids in the body. More severe cases of poisoning may require medications for the stomach, respiration, and the heart and circulatory system.


Do not consume honey made from the nectar found in rhododendron flowers. This honey is produced when bees feed on the nectar of rhododendron flowers, resulting in grayanotoxins being transferred to the honey. This honey causes vomiting, cardiac arrhythmia, convulsions and paralysis and is known as "mad honey." In many cases, according to the Nepal Medical College and Teaching Hospital regarding mad honey poisoning from rhododendron nectar, many people experience only mild symptoms of rhododendron poisoning, which tend to resolve within the first day.

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About this Author

Naima Manal's articles on health, diet, nutrition, alternative medicine, education, parenting, crafts, travel, home and garden and home improvement have appeared on eHow, Garden Guides, Trails, ConnectED, Helium and others. Manal received her B.S. degree in biology/pre-medical studies from Molloy College in 1994 and has been a freelance writer, teacher and homeschooling mom since 1993.