Why is my teenager always sick?

Potential Causes for Frequent Illness in Teenagers

One factor could be dry air, whether indoors or outdoors, which may decrease the body's ability to fend off viral infections. Additionally, allergies, insufficient sleep, stress, poor nutrition, or being in the company of a smoker can also contribute to increased sickness. It's worth noting that individuals who smoke are generally more susceptible to colds compared to non-smokers.