How Do Blood Pressure Medications Work?

July 18, 2022

High blood pressure is very common, with recent statistics showing that nearly half of adults in the U.S. are affected. The good news is that it’s also very treatable.

High blood pressure, or hypertension, occurs when there is resistance to the flow of blood from the heart to the rest of the body, putting excessive pressure on the walls of the arteries. This causes harm by increasing the workload of the heart and blood vessels – making them work harder and less efficiently. Often referred to as the “silent killer,” hypertension rarely causes symptoms unless it is very high for a prolonged length of time.

Untreated, long-term high blood pressure can lead to heart disease, heart failure, stroke, kidney disease and in extreme cases, blindness and even death. In fact, in 2019, over 100,000 deaths in the United States were caused by hypertension.

Understanding Blood Pressure Numbers

Blood pressure is determined by two things – the amount and force of blood your heart pumps (the faster your heart rate, the more blood that is pumped) and the amount of resistance to that blood as it flows through your arteries. The more blood your heart pumps and the narrower your arteries, the higher your blood pressure will be.

A blood pressure reading consists of two numbers:

Systolic: The first, or top, number measures the pressure in your arteries when your heart beats.
Diastolic: The second, or bottom, number measures the pressure in your arteries when your heart rests between beats.

A normal blood pressure for most adults is defined as 120/80 or lower. Below are the guidelines doctors use when evaluating blood pressure readings:

Less than 120/80 = Normal
120-129/80 = Elevated blood pressure
130-139/80-89 = Stage 1 hypertension
140/90 or higher = Stage 2 hypertension
180/120 or higher = Hypertensive crisis

It is important to remember that hypertension is not diagnosed based on one reading. If your reading is high in the office, your doctor may ask you to keep a log at home – measuring and recording your blood pressure at different times of the day. If your pressure is consistently high over a period of time, this is when hypertension may be diagnosed and treatment recommended. At-home blood pressure monitors are widely available for purchase.

Lifestyle Modifications to Reduce Blood Pressure

Elevated blood pressure and Stage 1 hypertension can sometimes be managed with lifestyle modifications only. These may include:

Eat a heart healthy, low-sodium, low-fat diet
Get moderate exercise (consult your doctor before beginning any exercise program)
Quit smoking
Reduce or eliminate alcohol and caffeine
Lose weight

If lifestyle changes don’t lower your blood pressure to a safe level, your doctor will likely recommend medication.

Medications for High Blood Pressure

There are many medications to treat hypertension that work in different ways to lower blood pressure. Listed below are the most common types/classes of medications prescribed along with a general explanation of how they work.

Thiazide Diuretics
Diuretics help the body get rid of excess sodium (salt) and water to help control blood pressure. Thiazide diuretics act directly on the kidneys to promote fluid removal through urination. They are often used in combination with other antihypertensive medications. (Note: Over-the-counter diuretics, often sold as “water pills” are not regulated and, therefore, not recommended.)

ACE Inhibitors
ACE stands for angiotensin-converting enzyme. Angiotensin is a chemical that causes the arteries to become narrow throughout the body, especially in the kidneys. ACE inhibitors help the body produce less angiotensin, which helps the blood vessels relax and open up, which, in turn, lowers blood pressure.

Angiotensin II Receptor Blockers (ARBs)
As mentioned above, angiotensin is a chemical that narrows the arteries. ARBs block the effect the chemical has on the blood vessels, preventing constriction and allowing them to remain open, thus reducing blood pressure.

Calcium Channel Blockers
When calcium enters the smooth muscle cells of the heart, it causes stronger, harder contractions. Calcium channel blockers prevent calcium from entering the heart cells resulting in less forceful contractions and reduced heart rate. Calcium channel blockers also relax and open up narrowed blood vessels which, together with the lower heart rate, helps to lower blood pressure.

Beta Blockers
Beta-blockers cause the heart to beat more slowly and with less force. This lessens the heart's output of blood and widens blood vessels, both of which can lower blood pressure. Beta blockers are often most effective when combined with other blood pressure medications.

The five medication types listed above are the most common but there are many other types of medications that may be recommended for you. And, some people will require more than one medication to effectively manage their blood pressure. Your doctor will work with you to find the right drug or combination of drugs and the right dosage to get your hypertension under control.

Early Detection Is Key

Although more common in older people, hypertension can occur in anyone – young, old, fit, not-so-fit, thin and overweight. That is why it’s important to have your blood pressure checked regularly, ideally at your annual physical exam with a primary care provider.

“The key is early identification,” says Ian Neeland, MD, Director of Cardiovascular Disease Prevention at UH Harrington Heart & Vascular Institute. “Once hypertension has been diagnosed, we work with each patient to find the right combination of lifestyle modifications and medications to reach their blood pressure goal. With the right treatment, complications of hypertension can be prevented, and, in some cases, damage can be reversed,” he adds. “The main takeaway is that good blood pressure helps people live longer, healthier lives.”