Vitamin B2, also known as riboflavin, is a water-soluble vitamin. Vitamin B2 can be involved in the composition of a variety of important coenzymes in the body, involved in the body’s metabolism and growth and development. However, vitamin B2 needs to be taken with attention to its use, and the common contraindications are as follows: 1. not to be taken on an empty stomach: consumption on an empty stomach may affect the absorption of vitamin B2, which may be rapidly metabolized out of the body and reduce the absorption rate; 2. not to be used with vitamin C: vitamin B2 may accelerate the oxidation of vitamin C if used with vitamin C, which may also reduce the absorption rate; 3. not to be used with Alkaline substances: Vitamin B2 is easily decomposed in alkaline environment, so avoid taking it with alkaline drugs or food, such as omeprazole sodium bicarbonate capsules, baking soda, edible alkaline noodles, etc.; 4. If vitamin B2 deficiency occurs, it is necessary to take the recommended dosage under the guidance of a doctor and not to overdose; if a newborn baby is too light to calculate the dosage of vitamin B2 supplements, it should be used with caution; 6. 7. Avoid using with anti-tumor drugs: Vitamin B2 and some anti-tumor drugs may reduce their effects if taken at the same time, such as methotrexate; in addition, vitamin B2 is easily damaged by visible light or ultraviolet light, and is easily destroyed by visible light if not stored away from light, so it is recommended to be stored away from light.