Long-term use of cold and flu preparations may cause harm, including: affecting the digestive system, causing gastrointestinal diseases; harming the liver and kidney system, affecting liver and kidney function; affecting the immune function, drug resistance and so on. 1. Affecting the digestive system and causing gastrointestinal diseases: Cold and flu preparations need to be absorbed and digested through the gastrointestinal tract. Taking cold and flu preparations for a long period of time will have a greater irritation on the gastrointestinal tract, which may cause abdominal pain, diarrhea, gastroenteritis and other gastrointestinal diseases. 2. Harming the liver and kidney system, affecting liver and kidney function: cold and flu preparations need to be metabolized through the liver and kidney system, long-term use of cold and flu preparations is likely to aggravate the burden on the liver and kidneys, affecting liver and kidney function, which may cause liver and kidney insufficiency and other serious problems. 3. Impact on immune function, drug resistance: long-term use of cold and flu preparations may reduce the body’s immune ability, resulting in low immunity, and a long period of time to take cold and flu preparations, easy to cause the body of the drug resistance, affecting the efficacy of the drug. Therefore, you should take cold and flu medicine according to your physician’s instruction, strictly abide by the number of times and the period of time prescribed by your physician, and not use the medicine on your own, in order to prevent adverse reactions and damage to your individual health.