Lewis & Short

ptarmĭcus, a, um, = πταρμικός, causing to sneeze, Theod. Prisc. 2, 3; Cael. Aur. Tard. 3, 5, 71.
Hence, as subst.: ptarmĭ-cum, i, n., that which causes sneezing, Cael. Aur. Acut. 1, 15, 138.
Plur., Cael. Aur. Tard. 3, 2, 42.