5a reductase inhibitor should be 5α reductase inhibitor, which is clinically used for the treatment of benign prostatic hyperplasia, including Finasteride, Erlichtamine, Epilast Tablet and so on. 5α reductase inhibitors are commonly used for the treatment of benign prostatic hyperplasia, which can shrink the enlarged prostate, inhibit prostatic hyperplasia, and improve the symptoms of urinary urgency, frequent urination, and increase in nocturia due to prostatic hyperplasia, and common drugs of the same kind include Finasteride, Erithromycin, and Eprileptal tablets. Its adverse reactions include allergy, depression, etc. It is contraindicated for those who are allergic to the components of the drug. Finasteride is not indicated for use in women and children, and is contraindicated in pregnant women or women who may become pregnant. 5alpha reductase inhibitors should be used correctly under the guidance of a doctor, do not use the drug on your own to avoid the adverse reactions associated with it.