It is best not to take vitamin C on an empty stomach. Vitamin C can improve the immunity and disease resistance of the human body, which is helpful for human health, but since vitamin C needs to be absorbed in the small intestine, it should be avoided when taken on an empty stomach. The concentration of stomach acid is relatively high when fasting, so taking vitamin C in this state will cause the effectiveness of the drug to diminish, and the drug will not be able to enter the small intestine more smoothly, so the drug will play a relatively small role. Taking vitamin C drugs on an empty stomach can also cause some irritation to the gastric mucosa and even cause nausea, vomiting and other stomach upset symptoms. It is best to take vitamin C after a meal to reduce the destruction of the drug by stomach acid, which is more conducive to the action of the drug, and does not violate the gastrointestinal mucosa.