The main diseases that teenagers are prone to are rickets, infections, myopia, dental caries and so on. 1. Rickets: Rickets is caused by the lack of calcium during adolescence, which is mainly manifested by restlessness, excessive sweating, beaded chest and so on. 2. Infection: Because teenagers are in the state of growing body, resistance is poor, it is easy to be invaded by some viruses or bacteria, thus causing the symptoms of infection. 3. Myopia: teenagers who are in the period of student, due to excessive use of eyes, it is most likely to lead to the occurrence of myopia, which is also the most common disease during the period of teenagers. 4. Dental caries: Due to eating too much sugar or not paying attention to cleaning the teeth during the teenage years, dental caries can occur in the long run. In addition to this, adolescents may also suffer from other diseases. When adolescents experience discomfort, they should go to the hospital immediately to avoid delaying their condition.