The common cold is mostly caused by viral infections. In the initial stage, the body may experience chills and fever. Once the body temperature reaches a certain level, the body no longer feels cold, and the immune system begins to mobilize extensively, preparing to eliminate the invaders (viruses). Cells infected by the virus are destined to be destroyed, and when these infected cells are killed, it forms a reaction similar to inflammation, which is one of the reasons for throat swelling and pain.
Moreover, during a common cold, both heart rate and cardiac output increase, as do the fluid flow in blood vessels, lymphatic vessels, interstitial spaces, and blood pressure. Pathways that are usually not very smooth become even more obstructed due to viral infection, accumulation of secretions, and metabolic waste, compounded by increased fluid flow, leading to swelling and blockage, such as the swelling of the tonsils and lymph nodes in the throat. Combined with the aforementioned inflammatory reaction, they stimulate and compress the nerve endings in the throat, causing a sensation of swelling and pain.
Tonics and supplements are mostly warm, high-calorie foods. For people with normal physical strength, consuming tonics during a common cold can further increase heart rate and cardiac output, as well as the fluid flow in blood vessels, lymphatic vessels, interstitial spaces, and blood pressure, exacerbating inflammatory reactions and local swelling, leading to more severe swelling, pain, and worsening of the condition, hence "tightening up."
However, for some weak common cold patients, because their body's heat production and combat readiness materials are insufficient, the immune system lacks enough strength to fight the virus, often leading to symptoms of the common cold lingering for weeks without recovery or recurring common colds. Such patients can consume tonics during a common cold to elevate their physical strength and body temperature to a normal level, thereby enabling them to overcome the virus.