Why does getting caught in the rain cause a cold but swimming doesn't?

After getting caught in the rain, the evaporation of water from the body takes away a significant amount of heat, causing the body to become chilled. Excessive internal coldness may lead to a cold caused by wind and cold (wind-cold type common cold). When swimming, the body is actively moving, but heat loss occurs at a relatively slower rate.

1. Getting caught in the rain causes drastic changes in the external environment surrounding the body, leading to excessive loss of body heat. For individuals with weaker constitutions, this makes it easier for cold pathogens to invade the body, resulting in chilling and reduced immunity. Viruses normally present in the mouth and nasal passages can then take the opportunity to infect the body, causing a cold.

2. While swimming, the entire body is submerged in water and thus protected from wind exposure, so body heat is lost relatively slowly. Therefore, during summer, one usually needs to swim for a long time before feeling cold or developing bluish-purple lips. However, if caught in heavy rain on a windy summer day, symptoms such as bluish-purple lips and full-body shivering may appear within about ten minutes. Rapid heat loss in such conditions can easily lead to a cold.

For colds caused by getting caught in the rain, it's important first to drink plenty of water, and secondly, to consume more fresh fruits and vegetables rich in vitamin C, which helps boost the immune system and resist cold viruses. Additionally, regular physical exercise should be maintained to strengthen overall health and improve physical constitution.