The nutrients between watermelon and lychee do not interact, there is no harm, you can eat together.
Watermelon and lychee are both relatively common fruits, and every 100g of watermelon contains 5.8g of carbohydrates, 303μg of carotene, and lycopene, vitamin C and other nutrients, which can replenish nutrients to the human body.
Every 100g of lychee contains 16.6g of carbohydrates, 41g of vitamin C, 151mg of potassium as well as calcium, sodium and other nutrients. Eating it in moderation can replenish vitamins, sugar and other nutrients.
Eating watermelon and lychee can supplement the above nutrients, but should be moderate, usually pay attention to a balanced nutritional diet.