Gui Zhi Tang is a formula that was developed around the year 220 C.E. and recorded in the Shang Han Lun (“Discussion of Cold Damage”). However, it is just as relevant today—especially in cool climates such as northern New Mexico—and is used for a wide array of conditions ranging from simple colds and flu to psycho-emotional instabilities. In TCM terms, Gui Zhi Tang is primarily used to treat “Wind-Cold invasion with Wei Qi deficiency and disharmony of Ying and Wei Qi,” which presents as sweating, chills and fever that are not relieved by sweating, aversion to wind, headache, stiff neck, nasal congestion, fatigue, and sometimes dry heaves. The tongue presentation is not much different than normal in this condition, but the pulse is floating and weak. This translates as a common cold or influenza in western terms.