The hazards and side effects of inserting a catheter include urinary tract infection, bladder stones, bladder atrophy, etc. 1. Urinary system infection: when the catheter is inserted, it may cause damage to the urethra and bladder mucosa, and the catheter is connected to the outside world, there may be bacteria and other pathogens along the catheter retrograde upward infection. 2. Bladder stones: If the catheter is not flushed for a long time or the catheter is not smooth, the urine is concentrated, forming crystals attached to the catheter is easy to form stones, leading to difficulties in removing the catheter. 3. Bladder atrophy: If the catheter is left in place for a long time, the bladder is in a state of emptiness for a long time without filling, which may lead to atrophy of the bladder. Insertion of catheter is usually used for difficult urination, catheterization during surgery, catheterization after surgery for urethral and bladder trauma, etc. Generally speaking, regular replacement and cleaning of catheter can reduce the occurrence of infections and stones, etc. If you need to keep catheterization, please consult a regular hospital.