From Japanese艾(mogusa, “mugwort”). The u is not strongly pronounced in Japanese, leading to its disappearance and the devoicing of the plosive. First used by Hermann Buschoff, a Dutch minister in Batavia, who wrote the first book about this remedy in 1674.
1676, Two Treatises, The one Medical, Of the Gout, And its Nature more narrowly search’d into than hitherto; together with a new way or discharging the same. By Herman Busschof Senior, of Utrecht, residing at Batavia in the East-Indies, in the service of the Dutch East-India Company. The Other Partly Chirurgical, partly Medical; Containing Some Observations and Practises relating both to some extraordinary cases of Women in Travel; and to some other uncommon cases of Diseases in both Sexes. By Henry van Roonhuyse, Physitian in Ordinary at Amsterdam. Englished out of Dutch by a careful hand. […], London: Printed by H.C. and are to be sold by Moses Pitt, page A3:
And thereupon she burned with her Moxa (of which hereafter) on my feet and knees, (to my best remembrance) about twenty little Escars, which looked like lit∣tle gray specks, without raising any blisters, or causing any after-pain; whereupon also all the pain of the Gout vanish’d.
1761, William Lewis, An Experimental History of the Materia Medica, or of the Natural and Artificial Substances Made Use of in Medicine: Containing a Compendious View of Their Natural History, an Account of Their Pharmaceutic Properties, and an Estimate of Their Medicinal Powers, so Far as They Can Be Ascertained by Experience, or by Rational Induction from Their Sensible Qualities, London: Printed by H. Baldwin, for the Author; and sold by R. Willock, page 380:
Moxa is celebrated in the eastern countries, for preventing and curing many disorders, by being burnt on the skin: a little cone of moxa, laid on the part previously moistened, and set on fire at top, burns down with a temperate glowing heat, and produces a dark coloured spot, the exulceration of which is promoted by applying a little garlic, and the ulcer either healed up when the eschar separates, or kept running for a length of time, as different circumstances may require.