What is the optimal timing for taking lisinopril (angiotensin-converting enzyme inhibitor) when experiencing hypertension (high blood pressure) in the morning and evening, specifically at 9am and 9pm?

From the Guidelines

Taking lisinopril once daily in the morning is the optimal timing for managing hypertension, as it provides a 24-hour duration of action to control blood pressure throughout the day and night. This approach is supported by the most recent evidence from the 2025 standards of care in diabetes, which states that preferential use of antihypertensives at bedtime is not recommended 1. The standard approach is to take the prescribed dose with breakfast, allowing for consistent blood pressure control. If high blood pressure readings persist at both 9am and 9pm despite morning dosing, it may be beneficial to speak with a doctor about adjusting the timing or dose. Some key points to consider when taking lisinopril include:

• Consistently taking the medication at the same time each day
• Monitoring blood pressure at various times to determine the effectiveness of the medication timing
• Potential benefits of splitting the total daily dose into two separate doses (morning and evening) or adjusting the timing to evening, as lisinopril reaches peak effectiveness 6-8 hours after taking it
• The possibility of increasing the dose or adding a second medication if blood pressure remains uncontrolled, as determined by a doctor. The most recent and highest quality study, published in 2025, does not support bedtime dosing as a preferential approach 1, and therefore, morning dosing remains the recommended timing for taking lisinopril.

From the FDA Drug Label

In most patients studied, onset of antihypertensive activity was seen at one hour after oral administration of an individual dose of lisinopril, with peak reduction of blood pressure achieved by 6 hours Although an antihypertensive effect was observed 24 hours after dosing with recommended single daily doses, the effect was more consistent and the mean effect was considerably larger in some studies with doses of 20 mg or more than with lower doses; however, at all doses studied, the mean antihypertensive effect was substantially smaller 24 hours after dosing than it was 6 hours after dosing

The optimal timing for taking lisinopril when experiencing hypertension in the morning and evening, specifically at 9am and 9pm, is not directly stated in the label. However, based on the pharmacodynamics of lisinopril, peak reduction of blood pressure is achieved by 6 hours after oral administration.

• To achieve peak reduction of blood pressure in the morning, lisinopril could be taken at 3am (6 hours before 9am), but this may not be practical.
• To achieve peak reduction of blood pressure in the evening, lisinopril could be taken at 3pm (6 hours before 9pm). Considering the antihypertensive effect is maintained during long-term therapy and an antihypertensive effect was observed 24 hours after dosing, taking lisinopril once daily, either in the morning or evening, may be sufficient to control blood pressure throughout the day. However, the best approach would be to consult a healthcare professional to determine the optimal dosing schedule for individual patients 2.

From the Research

Optimal Timing for Lisinopril Administration

The optimal timing for taking lisinopril, an angiotensin-converting enzyme inhibitor, when experiencing hypertension in the morning and evening, specifically at 9am and 9pm, can be informed by several studies:

• A study published in 1999 3 found that administering lisinopril at 10:00 PM resulted in a greater reduction of systolic and diastolic blood pressure from 6:00 AM to 11:00 AM, a period of higher cardiovascular risk.
• Another study from 2012 4 suggested that taking antihypertensive medication, including lisinopril, in the evening or at bedtime is more effective in treating morning hypertension.
• However, a 2015 study 5 comparing the antihypertensive effects of morning and evening dosing of valsartan, an angiotensin receptor blocker, found no benefit of evening dosing versus morning dosing on 24-hour blood pressure control.

Key Findings

Key findings from these studies include:

• The importance of considering the circadian rhythm of blood pressure when determining the optimal timing of antihypertensive medication administration 3, 4.
• The potential benefits of administering lisinopril in the evening or at bedtime to reduce morning blood pressure and cardiovascular risk 3, 4.
• The need for further research to determine the optimal timing of antihypertensive medication administration for individual patients 6, 5.

Administration Timing Considerations

Considerations for the timing of lisinopril administration include:

• The pharmacokinetics of lisinopril, which reaches peak serum concentrations 6-8 hours after oral dosing 7.
• The duration of action of lisinopril, which lasts for at least 24 hours 7.
• The potential impact of food, age, and co-administration of other medications on the bioavailability and efficacy of lisinopril 7.