Ma Huang (Ephedra sinica) is a traditional Chinese medicinal herb that has been used for thousands of years, particularly in the context of treating respiratory conditions such as cough, asthma, and bronchitis. In Traditional Chinese Medicine (TCM), Ma Huang is classified as a warm, acrid herb that releases the exterior and disperses cold. It is often used to address "cough due to external wind-cold invasion" and is especially indicated for coughs that are accompanied by chills, lack of sweating, and the presence of a thin, white phlegm—symptoms often associated with the TCM concept of "dampness" obstructing the lung.

The use of Ma Huang for cough is well documented in classic TCM texts such as the Shang Han Lun (Treatise on Cold Damage). Its active compounds, mainly ephedrine and pseudoephedrine, are known to act as bronchodilators and decongestants, providing symptomatic relief for bronchospasm and congestion, which can accompany certain types of cough.

While there is some pharmacological evidence supporting the use of ephedrine for bronchospasm, scientific studies specifically validating Ma Huang's efficacy for "cough (damp)" as defined in TCM are limited. Most of the support for its use in this context comes from historical and traditional practices rather than modern clinical trials. Furthermore, due to safety concerns, especially regarding cardiovascular and central nervous system side effects, the use of Ma Huang is restricted or regulated in many countries.