My brother and I, both optometrists, had a heart-to-heart discussion about the loss of one of our patients. We discovered he was not taking his medications as prescribed, which was leading to vision loss. When pressed, the patient said he had a choice of eating, supporting his family, or purchasing his medication.

He was under the impression that the $150 price for his generic Lipitor was “about the same” at any nearby pharmacy. We later realized that some of those nearby pharmacies charged from $11 to $25 for the same medication. Our studies revealed this type of discrepancy existed for almost all of his medications.

Our patient lost his life after suffering a stroke.  This was a bitter pill to swallow, but his loss led us to a period of discovery and determination to prevent this from happening again.

His life could have been saved with the knowledge of the vast price differences at retail pharmacies. That’s when my brother and I began our mission to promote transparency in retail drug pricing. I have left the practice of optometry to dedicate my career to addressing this problem.

This is when we met Sumanah, a 26-year-old event planner in New York City suddenly diagnosed with congestive heart failure.  Sumanah was like many typical 26-year-olds, without health insurance and no savings capable of paying for her medical bills.  Taking 10 medications for her condition, Sumanah was paying full price at what she “thought” was the cheapest pharmacy.  After she discovered that not only were some pharmacies cheaper for the same exact medication, she learned that some pharmacies could be upwards of 16 times more expensive than another pharmacy right across the street.  Using this information, Sumanah was able to price shop for the right pharmacy and save a lot on her prescription costs.  This story, although not uncommon, shows how important shopping around for medications can be.

In their May issue, Consumer Reports published an article confirming the experience Sumanah and many others have each time they go to fill a prescription.  The study focuses on five of the most prescribed medications in the U.S. and reviews more than 200 pharmacies for price comparisons.  The findings show the details of each pharmacy and drug researched as well as the overall discrepancy between the lowest cost pharmacy and the highest cost pharmacy.  For the same prescriptions, the difference was a whopping $749 per month or 447% between the highest and lowest cost options.

Price shopping prescriptions from one pharmacy to another can dramatically reduce out-of-pocket costs for patients without changing medications.  A recent Mayo Clinic study revealed 70% of Americans take at least one prescribed medication monthly and last year 50 million Americans decided not to take their medications due to the high cost.

Currently, medication non-adherence is cited by The IMS Institute of Healthcare Informatics as the largest contributor to health care costs in their June 2013 study, “Avoidable Costs in U.S. Healthcare.” The study shows that a patient’s inability to stay on a prescribed medication is estimated to cause over $100 Billion in avoidable health care costs due to the resulting health complications, hospital visits, and additional advanced treatment.

Many patients, and their health care providers, assume medications at different local pharmacies are about the same price. We’ve been operating solely in our roles as care providers for too long, and have been oblivious to changes in other parts of the health care system. While we work to keep patients healthy, parts of our health care system try to maximize profits at the expense of our patients and the entire system.

It’s time we wake up to the inequities our patients face. Lets join together to improve our health care system and save lives.

Ali Khoshnevis is an optomotrist and managing director, Tesser Health.

This post originally appeared on the Costs of Care Blog. Costs of Care is a 501c3 nonprofit that is transforming American health care delivery by empowering patients and their caregivers to deflate medical bills. Follow us on Twitter @costsofcare.