Prolonged use of vitamin C effervescent tablets may lead to urate, oxalate or cysteinate stones, etc. An overdose of this product may cause headache, nausea and vomiting. Vitamin C effervescent tablets may cause urate, oxalate or cysteinate stones when taken in large quantities over a long period of time. Overdose of this product (more than 1g per day) may cause stomach cramps, nausea and vomiting, frequent urination, headache, red and shiny skin, and diarrhea. Prolonged use of this product at 2-3g per day may cause scurvy when the drug is discontinued, so it needs to be slowly tapered off and discontinued. Vitamin C effervescent tablets can be used to prevent and control a variety of acute and chronic infectious diseases or other diseases, this product is also suitable for the healing period of trauma, the recovery period after the disease, the auxiliary treatment of allergic diseases, this product can also prevent and control scurvy. The contraindications of vitamin C effervescent tablets are not clear, it is recommended that patients who are not feeling well go to the regular hospital in time, follow the doctor’s instructions for symptomatic treatment, not unauthorized use of medication.