السَّنَا
A flowering plant used as a natural laxative, recommended alongside sanoot for digestive complaints.
عَلَيْكُمْ بِالسَّنَا وَالسَّنُّوتِ فَإِنَّ فِيهِمَا شِفَاءً مِنْ كُلِّ دَاءٍ إِلَّا السَّامَ
“Make use of senna and sanoot, for in them is healing for every ailment except death.” (meaning, not a literal translation)
This is the same hadith covered from the sanoot side in that entry — read together, the two entries cover the full saying, with senna being the half whose plant identity is not in dispute (unlike sanoot's genuinely contested identification).
Ibn al-Qayyim and later commentators discuss senna primarily as an effective, gentle purgative — a herbal practice broadly attested outside this specific narration as well. He notes it among the more reliably effective laxatives available in the classical materia medica, which likely explains its continued, independent use regardless of this hadith's weaker chain.
Senna remains a recognized and commonly used natural laxative in modern pharmacology, available over the counter in many countries — one of the clearer direct continuities between a classical Prophetic-medicine plant and current mainstream use.