If you had any doubts that drug prices have been on the rise, there is now proof: A recent study from AARP, the senior citizen advocacy group, found that in 2013 the average annual retail price among 622 widely used prescription drugs had more than doubled in less than a decade – from $5,571 in 2006 to $11,341 in 2013. To be clear, those costs are for taking one drug for just one year. That amount equaled almost 75% of the average Social Security retirement benefit ($15,526), nearly 50% of the median income for Medicare beneficiaries ($23,500) and more than 20% of the median U.S. household income ($52,250) over the same time period.

Many already suspected that prices for existing drugs have been increasing steadily, and at a faster pace, since 2007, and this study confirms it. Driven entirely by manufacturer price hikes, it's a trend that's expected to continue. In 2006, for example, the average annual percentage price increase was 3.6%; during 2013, it was 9.4%. The price increases exceeded the corresponding rate of general inflation every year from 2006 through 2013 (the duration of the study). Our concern with the prices we're seeing is that the overall trend is really accelerating, Leigh Purvis, one of the study's authors and the director of health services research at AARP's Public Policy Institute, told the Associated Press.

Rising drug prices can be especially problematic for seniors because Medicare plans typically require patients to share more of the costs than employer or other commercial health insurance plans do. That cost sharing could be as much as half the dollar amount of the most expensive drugs, according to Purvis. This affects everyone, said Purvis, because even those who don't use prescription drugs essentially share in the costs through higher insurance premiums and taxes that fund Medicare, the U.S. Department of Veterans Affairs and other health programs.

High drug costs are also a problem for the growing number of people taking multiple drugs, or who need long-term meds for chronic health conditions. According to the U.S. Centers for Disease Control, 30.8% of 45- to 64-year-olds and 51.8% of the 65-plus crowd took three or more drugs in the last 30 days during the period from 1999 to 2002. From 2009 – 2012, the most recent data available, those figures rose to 34.7% of 45- to 64-year-olds and 64.8% of those age 65 and older – increases of 12.66% and 25.10%, respectively. With more adults taking more meds, and drug prices rising, it's becoming increasingly difficult for many to afford the prescription drugs they need, which can lead to worse health outcomes and higher healthcare costs down the road.

Despite rising prescription drug costs, there are some things retirees can do to save. A good first step is to ask your doctor if there's a generic version of the drug you're taking (and if so, make sure you get the prescription for it). Generic pills often cost about 85% less than their brand-name counterparts (if there are several generic versions available). Today, generics drugs account for about 87% of prescriptions filled in the U.S. Although their prices typically decline over time, you can't count on it, so it's important to find other ways to save.

Another good option is to shop around for the best price. Even though it seems like your prescription should cost the same no matter which pharmacy you use, that's not the case. A prescription at one pharmacy, for example, might cost $100, while the same prescription at a pharmacy across the street could end up costing just $20. Call each pharmacy in your area to ask how much your prescription will cost to fill, based on your health insurance coverage, or try an online price comparison tool, such as GoodRX or RXPriceQuotes. For more ways to save, read 6 Ways Retirees Can Save on Prescription Drugs and Apps That Find the Cheapest Drug Prices.

AARP's report reveals that average annual increases in retail prices for widely used prescription drugs have exceeded the rate of general inflation every year from 2006 to 2013. This is especially hard on seniors because the $11,341 average annual price tag for drugs equals about three-quarters of the average Social Security retirement benefit, and nearly 50% of the median income for Medicare beneficiaries. That doesn't leave much on the table.

Asking your doctor for generic drugs, shopping around for the best price and signing up for a Medicare Prescription Drug Plan (Part D) are all ways to save on drug costs. Also, keep in mind that a healthy lifestyle may help you save not only on drug costs, but your overall healthcare expenses as well. See Invest in Your Health for a Good Retirement to learn more.