My friend Naomi was diagnosed with high blood pressure and went on medication prescribed by her doctor. Within a few months, she was back at the doctor’s office, her blood pressure heading up instead of down. It turned out that she was not taking her medication properly — and that the drug she had been given was not the most appropriate one for her.

Naomi is hardly alone. Nearly one-third of US adults have hypertension (blood pressure higher than 140/90), a symptomless disease that, if not appropriately managed, can result in a heart attack or stroke.

I spoke to Mark C. Houston, MD, director of the Hypertension Institute at Saint Thomas Medical Group in Nashville and author of What Your Doctor May Not Tell You About Hypertension. He told me that failure to take medication properly is one primary reason why high blood pressure is often so hard to get under control.

Another problem is that finding the right medication or combination of medications can be tricky, and often doctors have resorted to a “try this, try that” approach. Good news: Recent research has helped clarify which types of drugs are likely to work best for certain patients. So if you have recently been diagnosed with hypertension or if your medication is not working, it’s time to talk to your doctor about…

Your levels of the blood pressure-modulating enzyme renin. A recent study showed that people with different blood levels of renin responded differently to various hypertension drugs — and that taking the wrong kind of medication actually made blood pressure go up.

Patients with high-renin hypertension responded best to…

  • Angiotensin-converting enzyme (ACE) inhibitors, which reduce blood pressure by blocking an enzyme that produces angiotensin II (a hormone that causes blood vessels to narrow)… dilating arteries… and reducing inflammation and oxidative stress. They also decrease clotting, further protecting against heart attack and stroke.
  • Angiotensin receptor blockers (ARBs), which work by blocking receptors for angiotensin I (the precursor to angiotensin II). They also dilate blood vessels and ease inflammation and oxidative stress.
  • Direct renin inhibitors, which reduce angiotensin I and relax blood vessels.
  • Beta-blockers, which reduce blood pressure by reducing nerve signals to the heart and blood vessels and slowing the heart rate.

People with low-renin hypertension responded best to…

  • Calcium channel blockers, which combat high blood pressure by preventing calcium from moving into arteries and heart muscle cells and allowing arteries to dilate.
  • Diuretics, which cause kidneys to remove excess sodium and water from the body and dilate blood vessel walls.

How your blood pressure is being measured. The blood pressure cuff in your doctor’s office may not be reliable if you are prone to “white-coat hypertension” (blood pressure that rises from the anxiety of being in the doctor’s office) or “masked hypertension” (lower blood pressure numbers in the doctor’s office but consistently higher numbers at other times).

Ask your doctor if you might benefit from using a high-quality home blood pressure monitor (sold over the counter in pharmacies and online for $50 to $150) to keep track of your readings every day. Also discuss the option of using a 24-hour ambulatory blood pressure monitor. A cuff worn on your arm and a small device clipped to your belt record your pressure every 15 to 30 minutes for 24 hours… then your doctor analyzes that data.

How consistently you take your medicine. The different types of hypertension drugs can cause a variety of side effects, such as fatigue, memory problems and sexual dysfunction. If you experience these or other problems, do not suffer in silence — and certainly do not keep silent if you sometimes skip doses to avoid side effects. Tell your doctor and discuss alternative drugs.

But if you are conscientious about taking your meds, be sure your doctor knows that, too. Otherwise he or she may wrongly assume that any lack of effectiveness is due to your noncompliance rather than to a need for a different medication.

When to take your medication. Since blood pressure medications are effective for only 24 hours, it is important to take them at the same time every day. Don’t drive yourself crazy if you are an hour early or an hour late, but do not be off by several hours. Very important: Most heart attacks and strokes happen between 3 am and 10 am, which is when blood pressure typically is highest. That’s why the new recommendation generally is to take your medicine at night, Dr. Houston said — to block that early morning blood pressure spike.