There is generally no harm in swimming in a regular swimming place in normal physical condition. However, if the swimming place is not regular, swimming in abnormal physical condition may cause infection, induce or aggravate diseases, accidents and others. 1. Infection: there are a lot of bacteria and viruses in the water, and if you don’t clean up after swimming, you will have the risk of conjunctivitis, trachoma, otitis media, dermatitis, ringworm and athlete’s foot, etc.; women’s menstruation may cause urinary tract infections and so on. 2. Induce or aggravate disease: the lower temperature of swimming pool water may lead to vasospasm, patients with a history of underlying diseases such as hypertension, coronary heart disease, can lead to disease attack. Cervical spondylosis, arthritis patients may also aggravate the condition; if the resistance is poor, it will also cause colds, laryngitis, abdominal pain, diarrhea and so on. 3. Accidents: swimming before the warm-up exercise, can lead to cramps, muscle ligament strains, accidents; fasting swimming can lead to hypoglycemia, and even fainted in the pool accident; in unfamiliar with the natural waters of swimming, accidents may also occur. 4. Others: Poor purification of swimming pool water and non-compliance of water pH can cause dental injuries; too much time in the water may lead to dry skin and damage the skin. It is recommended that you should choose a safe swimming place, do a good warm-up exercise before swimming, combine with your own condition, moderate exercise, and consult a doctor in time if you feel unwell.