Vitamin C belongs to the body’s micronutrients, generally does not cause harm to the human body, but long-term use of vitamin C can lead to the following hazards: long-term use of 2-3 grams per day can be caused by scurvy after stopping, so it is advisable to gradually reduce the amount of stopping. Long-term use of large amounts of vitamin C tablets can cause urate, cysteine or oxalate stones. Overdose (more than 1 gram per day) may cause diarrhea, red and bright skin, headache, frequent urination (more than 600 mg per day), nausea and vomiting, stomach cramps and other adverse reactions. Vitamin C tablets are used for the prevention of scurvy and as adjunctive treatment for various acute and chronic infectious diseases and purpura. It should be taken according to the recommended dosage under the guidance of a doctor, and should not be blindly ingested in large quantities, and should be taken to a doctor in time if any uncomfortable symptoms occur.