A common problem among people with chronic illnesses, such as heart disease, diabetes, HIV or asthma, is that they don’t remember to take their prescription meds. But just because it’s prevalent doesn’t mean this problem isn’t a big deal. According to a recent review in the Annals of Internal Medicine, simple nonadherence could kill nearly 125,000 Americans each year and cause at least 10 percent of hospitalizations in this country, The New York Times reports.

The numbers in the medical journal’s review are staggering. According to several recent studies, doctors estimated that U.S. patients never filled between 20 and 30 percent of medication prescriptions doctors gave them. In addition, researchers found that approximately 50 percent of medications for chronic illnesses aren’t taken as prescribed, and among people who take their prescription meds—whether it’s for a simple infection or a life-threatening illness—patients typically take only half of their prescribed doses.

Additionally, the Annals report cited studies that showed about a third of kidney transplant patients don’t take their anti-rejection medications; 41 percent of heart attack patients don’t take their blood pressure medications; and about half of children with asthma either don’t use their inhalers at all or utilize them inconsistently. (This nonadherence is estimated to cost the American health care system between $100 billion and $289 billion annually.)

“When people don’t take the medications prescribed for them, emergency department visits and hospitalizations increase, and more people die,” said Bruce Bender, PhD, codirector of the Center for Health Promotion at National Jewish Health in Denver, in a recent comment on the review. “Nonadherence is a huge problem, and there’s no one solution because there are many reasons why it happens.”

According to the review, reasons for nonadherence include high drug costs, high copays, denial of illness and dislike of long-term medication.

The journal’s commentary concluded by listing several changes in the U.S health care system that could help to improve adherence: digital technology to help doctors and pharmacists remind patients to stay on their medications, drugs that combine multiple meds into one pill and simplifed dosing.

Scientists noted that these findings may help explain why drugs that perform very well in studies (such as hepatitis C medications, which can cure up to 95 percent of patients) often fail to measure up once the drug hits the commercial market and why so many patients don’t get better, even when they’re prescribed medicines that should keep their disorders under control.

Worried about forgetting your meds? Click here for some easy tips to remain adherent.