Against a Wen is an Old English metrical charm and medical text found in the Royal MS. 4A.XIV, British Museum. It appears to describe a remedy for ridding oneself of a wen, which is an Old English term for a cyst or skin blemish. As cysts are commonly mobile masses on the skin, the charm is written to the wen itself, asking it to leave. The charm prescribes methods for curing the blemish, and describes it as it gradually shrinks until it disappears.
Elliott Van Kirk Dobbie, The Anglo-Saxon Minor Poems, vol. VI of The Anglo-Saxon Poetic Record, Columbia University Press, New York, 1942. ISBN 0231087705/0-231-08770-5