Rhododendron dauricum L. (Rhododendri Daurici Folium)
Nature and flavour. Pungent and bitter, cold; Lung system.
Traditionally classed as stopping cough and dispelling phlegm, and recorded for cough with copious sputum and for congested breathing. It is a regional drug: the leaf of a rhododendron that grows across the north-east, used in the local and official materia medica rather than in the earliest classical canon, and it entered the modern Chinese pharmacopoeia as a leaf drug with an essential-oil fraction. The traditional picture is of a cold drug used for a hot, congested presentation, and it is classically paired with the warming cough drugs rather than substituted for them.
性味归经。辛、苦，寒；归肺经。
传统归类为止咳祛痰，古籍与地方本草用于痰多咳嗽、气喘。本品是地方性药品：为分布于东北的杜鹃属植物的叶，见于地方本草与现代药典，而非最早的经典本草；现代药典以叶入药，并记载其挥发油成分。传统认为本品性寒，用于属热、属壅滞之证，在配伍中与温性止咳药相须而用，不作简单替代。
危险来自这个属本身。杜鹃属叶含梫木毒素类二萜（梫木毒素即其中之一），此类毒素的中毒在中国之外亦有明确记载，最著名者为由杜鹃花蜜所致的中毒。文献描述的过程包括流涎、出汗、恶心呕吐、头晕乏力、血压下降与脉搏减慢，重症可致意识丧失；报告中亦有心脏传导影响与惊厥。因其作用落在血压与心率上，原有低血压、心动过缓，或正在服用作用于心脏与循环系统药物者风险更大。品种混淆是另一实际风险：杜鹃属其他种毒性明显更强 —— 羊踯躅被列为大毒并曾致死亡中毒 —— 采错灌木的叶不是本品的弱化版，而是另一种危险。自行采挖或无标签的叶不应使用。不用于儿童。孕期与哺乳期安全性未确立；传统列为孕妇忌用。
1 related entry.