Modern Science View :

Tulsi is a well-known immunomodulatory herb that might improve the individual’s ability to fight against common cold. Tulsi has antimicrobial, anti-allergic and anti-inflammatory properties, therefore prevents the inflammation of the nasal mucous membrane. It also prevents the regular recurrence of the common cold symptoms. Another study states that Tulsi helps gives relief from cough.

Ayurvedic View :

Common cold is caused by an aggravation of Kapha and weak digestion. When the food we eat is not fully digested, it changes into Ama. This Ama reaches the respiratory system in the form of sputum and causes cold or a cough. Tulsi has Deepan (appetizer), Pachan (digestive) and Kapha balancing properties which help to reduce Ama and expel the excessive sputum from the body.