The European Commission has approved the administration of thyme for cough and bronchitis.(1) In the case of thymol and carvacrol, a broad spectrum of effects against bacteria involved in the infections of the upper respiratory tract has been observed. It is believed that thymol and carvacrol exert their antibacterial activity through complex formation with the proteins in the bacterial membrane. A synergistic effect has also been demonstrated for thymol and carvacrol. Furthermore, it has been demonstrated that sufficient doses of thymol and carvacrol have relaxant effects on the trachea. Various clinical trials have confirmed the efficacy of thyme on productive cough. In a randomized double-blind clinical trial, 60 patients with productive cough were administered thyme syrup or bromhexine syrup for a period of 5 days. According to the patents’ self-reports, there existed no significant difference between the two groups and both observed identical improvement by both of the medications. There was significant non-statistical progress in health of non-smokers compared to smokers in both groups.(2)
Commission E has approved the use of fennel for treatment of inflammation of mucus membranes in the upper respiratory tract. Fennel is expectorant and it enhances the mucociliary activity of the ciliated epithelium of the respiratory tracts. The chemical structure of the anethole present in fennel resembles that of catecholamines (adrenaline, noradrenaline and dopamine) and like adrenaline, fennel is a bronchodilator. In guinea pig, administration of fennel essential oil as inhaler caused mild antitussive or cough suppressant effects on coughs induced by mechanical stimulants. The antibacterial properties of fennel essential oil is determined as identical or more than the antibiotics streptopenicillin, penicillin and tetracycline.(2)
Thyme and Fennel
To evaluate the effects of thyme and fennel essential oils in treatment of cough, in a controlled, randomized, double-blind clinical trial, 119 patients of more than 14 years of age suffering from acute cough were administered three times per day, 20 drops Tussivin Oral Drop (containing sweet fennel and Iranian thyme essential oils), clobutinol drop or placebo for 3 days. At the end of this course, complete recovery was reported in the group receiving Tussivin Oral Drop and clobutinol as 50% and in the placebo group 9.1%. The efficacy of Tussivin Oral Drop, clobutinol and placebo, in patients with productive cough, was reported as 66.7%, 55% and 14.3%, respectively, and 56.5%, 55% and 20% in patients with nonproductive cough. In the degree of improvement of cough, significant difference was observed between Tussivin Oral Drop, clobutinol and placebo (p<0.01), but no significant difference was observed between Tussivin Oral Drop and clobutinol (p>0.4).(4)
Considering the expectorant properties of fennel, alleviation of cough along with aiding with expulsion of mucus is among the properties of Tussivin Oral Drop.