Most people with hypertension require two or more blood pressure medications to control their blood pressure. By combining drugs from different classes, you'll likely be able to reduce your blood pressure more than if you use a single drug.

In fact, a 2009 analysis of 42 studies in the American Journal of Medicine found that combining two different drugs worked better than doubling the dosage of a single drug. That's because the actions of two medications can complement each other.

For example, diuretics reduce blood pressure by increasing the excretion of sodium and water by the kidneys. In some people, this effect stimulates the release of blood pressure-raising hormones to compensate for the drop in blood volume. Adding an ACE inhibitor blocks the actions of these hormones and improves blood pressure control.

Combination therapy involves taking either a separate dose of each medication or a single pill that contains two or more different medications (a fixed-dose combination drug). Most fixed-dose combination drugs contain a thiazide diuretic and an ACE inhibitor, ARB or beta blocker. Some examples are Capozide (hydrochlorothiazide plus captopril), Diovan HCT (hydrochlorothiazide plus valsartan Inderide (hydrochlorothiazide plus propranolol) and Lotensin HCT (hydrochlorothiazide plus benazepril).

Other fixed-dose drugs combine an ACE inhibitor and a calcium channel blocker, for example, Lotrel (benazepril plus amlodipine), or an ARB and a calcium channel blocker, for example, Exforge (valsartan plus amlodipine).

There are even a few three-drug combinations—Exforge HCT (valsartan, amlodipine and hydrochlorothiazide) Tribenzor (olmesartan medoxomil, amlodipine and hydrochlorothiazide) and Amturnide (aliskiren, amlodipine and hydrochlorothiazide).

Fixed-dose combination drugs are more convenient (fewer pills to take each day) and may be less expensive than taking each drug individually. In addition, the risk of side effects may be reduced because the fixed-dose combination typically contains smaller doses of each medication than when the drugs are taken separately.

However, fixed-dose combinations reduce dosing flexibility—the dosage of each medication in the combination cannot be adjusted separately. Thus, fixed-dose combination drugs are most appropriate for people who have found that the combination of the two drugs effectively controls their blood pressure when taken separately at the same dosages as in the combination pill.

Publication Review By: Lawrence Appel, M.D., and Rafael H. Llinas, M.D.

Published: 16 Jul 2013

Last Modified: 16 Jul 2013