Cowslip (Primula veris) has a history of use in traditional European herbal medicine for treating respiratory ailments, including cough and bronchitis. The flowers and roots contain bioactive components such as saponins, flavonoids, and phenolic glycosides, which are believed to contribute to its expectorant and anti-inflammatory effects. Recent scientific research supports some of these traditional uses. Clinical studies and pharmacological investigations have indicated that cowslip extracts, particularly in combination with other herbs (like thyme), can reduce the severity and frequency of cough, especially of the spastic (irritative) type associated with upper respiratory tract infections.

The German Commission E, a well-respected herbal monograph authority, recognizes cowslip as an approved treatment for catarrh of the respiratory tract, citing its expectorant action. The efficacy is generally attributed to the saponins in cowslip, which can decrease the viscosity of bronchial secretions and facilitate expectoration. However, most clinical studies use cowslip in combination with other herbs, making it difficult to isolate its individual effectiveness. Overall, while evidence supporting cowslip’s use for spastic cough is not extensive or highly robust, there is a moderate level of scientific validation corroborating its traditional application. Safety concerns exist for individuals with allergies to Primulaceae or with asthma, so caution is recommended.