Folic acid is a water-soluble B vitamin. In elderly patients before using this drug should be ruled out the presence of vitamin B12 deficiency, such as vitamin B12 deficiency can increase the burden of vitamin B12 and neurological symptoms, taking large doses of folic acid may lead to severe irreversible neurological damage. It is classified as Grade A in the pregnancy safety classification because folic acid can affect the absorption of the trace element zinc, and taking excessive doses of folic acid can lead to zinc deficiency and, in pregnant women, may cause fetal growth retardation and an increase in low birth weight babies. It can be given prophylactically to women during pregnancy, as folic acid deficiency can cause damage to the fetus and lead to neural tube defects. However, it should be used with caution in women of childbearing age with folic acid-dependent tumors. The gastrointestinal tract can show symptoms such as bad taste in the mouth, food aversion, nausea and abdominal distension with long-term high doses, and the nervous system can show confusion, irritability and sleep disturbance, and the urinary system can show yellow urine. Folic acid rarely causes symptoms of toxicity, and any excess dose can be eliminated from the urine, so adverse reactions are rare, but there are still rare allergic reactions. Alcohol should not be consumed during the drug administration.