Published September 1, 1990.
List of German Commission E Monographs (Phytotherapy)
Rhododendri ferruginei folium, rusty-leaved rhododendron.
Rusty-leaved rhododendron consists of the dried leaves of Rhododendron ferrugineum L. [Fam. Ericaceae] and preparations thereof.
Rusty-leaved rhododendron leaves are used exclusively in combination preparations in the treatment of hypertonia, muscle and joint rheumatism, arthroses, hardening of muscles; muscular pain, weak connective tissue; neuralgia, sensitivity to weather change, sciatica, trigeminus neuralgia, migraine, headaches, intercostal neuralgia, gout, lithiasis, and in geriatric drugs for disorders and complaints associated with aging.
The efficacy of the drug in the above-named areas has not been proven.
Rhododendron species can contain toxic diterpene with an andromedic basic structure. There is contradictory evidence on the occurrence of andromeda derivatives in rhododendron. Reports of grazing animals being poisoned by rhododendron indicate that compounds of these groups do occur in the leaves. Symptoms of acute grayanotoxine poisoning are a drop in blood pressure, bradycardia, cramps, cardiac arrest, and cessation of breathing. Chronic toxicity of the compounds in animals is relatively minimal. In humans, the following poisoning symptoms were reported after eating honey (among other foodstuffs) containing grayanotoxine: Vomiting, diarrhea, pains and cramps in the gastrointestinal tract, joint pains, impaired balance, difficulty in breathing, sensitivity of the central nervous system; paralysis, as well as burning and itching of the skin and mucous membrane.
If the drug is taken over a long period there is also danger of intoxication with hydroquinone because of the arbutin contained in the drug. There are no reports of serious instances of poisoning of patients used to taking it as an infusion in folk medicine (daily dose 5 - 6 g).
Due to the insufficiently proven efficacy of the drug and its pharmaceutical preparations as well as the associated risks, therapeutic use cannot be recommended.