Researchers have discovered a dangerous but largely ignored combination of weak bones and high blood pressure treatment. What’s the connection? Your risk of falling and breaking your hip is almost doubled when you are just starting out on new medication for high blood pressure treatment. In this case, the combination is particularly scary, the experts reported.

Each year about 30 to 50 percent of people age 65 years and older experience a fall , with hip fractures occurring in about 1% of falls. And about a third of people who have fractured their hip die within the first year. When you combine these statistics with the fact that over half of people over 65 have hypertension, and most of those will be started on medication for high blood pressure treatment, you can see the enormity of the problem.

Seniors often pay a high price when taking ACE inhibitors or beta blockers

Researchers from the University of Toronto have reported that antihypertensive drugs, particularly angiotensin II–converting enzyme (ACE) inhibitors and beta-adrenergic blockers, are associated with an increased risk for falls and hip fracture among the elderly when they first begin taking the drugs.

After analyzing data from more than 1.6 million elderly Canadian residents, they found a shockingly high number of individuals who fractured their hip within 45 days of starting high blood pressure treatment. Among 301,591 individuals who started antihypertensive medications, 1,463 had hip fractures within the treatment initiation period (the first 45 days). The risk for hip fracture during this period was a whopping 43% greater than the risk before and after starting treatment.

All the different classes of antihypertensive drugs that were evaluated, including thiazide diuretics, ACE inhibitors, angiotensin II–receptor blockers, calcium channel blockers, and beta-adrenergic blockers, were associated with increased risk. However, upon further examination, the blood pressure treatments associated with  increased hip fracture risk that reached statistical significance were the ACE inhibitors and beta-blockers. The risk of early fracture rose by 53% for patients started on an ACE inhibitor and by 58% for those on beta-blockers.

Why increased fall risk? Research believes it is feeling of dizziness or lightheadedness

ACE inhibitors are widely prescribed blood pressure treatments and include popular generics like lisinopril, benazepril, and enalapril. They work by blocking an enzyme needed to form a substance that narrows blood vessels. This allows blood vessels relax and widen so blood can flow through the vessels more easily, which reduces blood pressure. Beta-blockers are also widely prescribed antihypertensives which block the affects of adrenaline in the heart so that it does not have to work as hard, which in turn lowers blood pressure. The beta-blockers include such popular generics as atenolol and metoprolol.

Whereas previous studies have associated antihypertensive drugs with an increased risk for falls and fractures among the elderly, this was the first study to find an increased risk of fractures immediately after starting on high blood pressure treatments. The older research on fracture risk looked more at the effects of taking blood pressure medications for long periods of time, sometimes years. This long-term exposure has also been found to increase rates of fractures in the elderly. The underlying mechanism is thought to be related to a decrease in bone mass. Why the drugs are also associated with an immediate increased risk of fracture is thought to be more related to the orthostatic or postural hypotension they cause, which is the feeling of dizziness or lightheadedness you sometimes feel when first standing up.

In any case, the researchers reporting their findings advised caution in the elderly when starting any new blood pressure lowering medication. They expressed their concern that while high blood pressure treatments with medication prevent cardiovascular events, they may hasten hip fractures.

[1] American Society for Bone and Mineral Research (ASBMR) 2012 Annual Meeting. Abstract 1055. Presented October 13, 2012.

This post originally appeared in 2012 and has been updated.