If it's overnight and lemonade is kept in the refrigerator, you can't eat it.

After citric acid reacts with air, there will be sediment, which is not good for the stomach. In severe cases, it will lead to vomiting. There is no harm in drinking lemonade overnight, but lemonade is easy to oxidize, so there are often water spots on the glass of lemonade overnight. In addition, the temperature is high in summer, and lemonade is easily contaminated by bacteria, leading to diarrhea, so it is better not to drink lemonade overnight at this time.

Extended information:

1. It is best for people who are prone to slight cold stomach acid not to drink lemonade at night. It is recommended to drink it one hour after dinner at night, and it will be better to drink it with appropriate amount of honey.

2. Although lemonade can be kept for a long time, its antioxidant components are unstable and volatile easily. Low temperature can slow down the oxidation process, so it should be kept in the refrigerator. It is no problem to keep it in the refrigerator for 2 days in summer.

3. Lemon contains a lot of vitamin C, which is easily oxidized. Compared with fresh lemon slices, the content of vitamin C is definitely lower. The taste of water will be slightly worse, but the difference is not very big. If you soak in water, there is little difference in efficacy. Soaking in water with sun-dried lemon slices can also whiten your skin.

Reference: Baidu Encyclopedia-Lemonade.