Failure of enalapril to lower blood pressure may be related to improper dosage, substandard monotherapy, and improper type of drug. 1. Improper dosage: If the patient does not take enough enalapril, it will not have the effect of lowering blood pressure. Usually the recommended dosage is 5mg once a day, and then the dosage can be adjusted to 10~40mg per day in 2~3 times according to the use of the drug. 2. Inadequate monotherapy: Usually, the use of antihypertensive drugs is not necessarily just one type of drug, considering that patients need to combine other types of drugs used together, such as metoprolol, atenolol and other beta-receptor antagonists; hydrochlorothiazide, furosemide and other diuretics. 3. Inappropriate type of drug: It may also be because enalapril is not sensitive to the patient’s own therapeutic effect. Patients need to change the type of drug, available irbesartan, chlorosartan and other angiotensin II receptor antagonists, or nifedipine, verapamil and other calcium channel blockers. It is recommended that patients whose blood pressure cannot be lowered by enalapril go to the hospital in time and adjust the drug treatment program under the guidance of the doctor.