Mike O’Meara’s life runs on a tight schedule.

Every morning, after a glass of juice and breakfast, the 70-year-old picks up his medication from a blue labeled tray his wife Beth prepared and gulps down 12 and a half pills.

At noon, he swallows three more.

Around dinner time, three more.

And before bed, he reaches for his nightstand drawer to grab his last doses of the day: seven and a half pills.

O’Meara has been diagnosed with diabetes, kidney problems and heart failure. He depends on 16 medicines — 26 pills a day — to manage his health. Taking a variety of pills is not unusual for older patients, but the American Heart Association Monday warned heart failure patients and their doctors that they need to monitor the variety of drugs because of the possibility of unintended consequences.

In the journal Circulation, the American Heart Association said heart failure patients take an average of nearly seven prescription medicines a day and 40 percent of Medicare patients with heart failure also have five or more other chronic diseases. According to the latest data from the Centers for Disease Control and Prevention, roughly 5.7 million Americans live with heart failure.

Heart failure is caused by the cardiac muscle’s inability to pump blood efficiently enough to support the body’s needs. Symptoms include shortness of breath, fatigue and swelling in the legs.

Among the most dangerous drugs for interaction, according to the study, were several commonly used to treat cancer, migraines, Parkinson’s disease and mental health issues.

Dr. Davy Cheng, a professor at Western Ontario University’s medical school and co-author of the statement, said he hoped it would serve as a “current up-to-date review” of the risks associated with medication given to heart failure patients.

Medications were ranked by their potential for harm based on the severity of the reaction and onset from when the last dose was taken. Researchers formulated the ratings based on existing data, scientific trials and package inserts.

More than 32 prescription medications were found to cause direct damage to the heart. For example, anthracyclines, a class of chemotherapy compounds frequently used to combat cancer, contain five agents known for causing irregular heart rhythms and inflammation. Researchers also linked ergotamine, a migraine medication, to heart valve problems.

Commonly used over-the-counter drugs such as ibuprofen can contain high amounts of sodium and damage the heart by causing fluid buildup.

Heart failure is a progressive disease, which means the medicines proven effective today may stop working in a few months, said Dr. Gurusher Panjrath, an assistant professor of medicine at the George Washington University’s medical school in Washington, D.C.

And since many heart failure patients are also dealing with other health conditions, keeping track of the variety of drugs they are taking can be complicated. Many of these patients obtain pills from multiple doctors who seldom consult one another on what he or she prescribed. And without oversight, the prescription cocktail can lead to deadly reactions.

“Heart failure is not an easy disease like the flu that you can forget about it then it’s gone,” Cheng said. “Heart failure is a serious disease.”

The AHA statement contained a list of recommendations for medical professionals to better understand their patients’ prescription drug regimens. It suggests doctors regularly do a comprehensive review of the patient’s medicines, including dosage and frequency, and consider verifying the information with the patient’s pharmacy. It also recommended that physicians avoid prescribing new medication to alleviate side effects from other drugs.

Researchers also advised doctors to carefully consider the risk and benefit of every medication before prescribing it to a patient.

While the statement emphasizes a doctor’s role in improving care coordination, patient engagement also plays a key part in bettering prescription drug management, said Robert Page, professor of clinical pharmacy at the University of Colorado School of Pharmacy and lead author of the study. He recommended patients bring an accurate and complete list of medications to every doctor’s visit. Individuals should also learn the risks of their medications and communicate frankly with their doctors.

“Patients need to be engaged now more than ever,” Page said. “Medicine has become very complex.”

So every morning, before breakfast but after his glass of juice, Mike O’Meara’s wife Beth stirs him awake to measure his vitals and record them in a logbook laying on his nightstand.

Glucose. Temperature. Oxygen saturation. Heart rate. Weight. Blood pressure.

And at every appointment, Beth is present with book in hand to share the details of her husband’s condition with his doctors. Mike said his medical team considers the book “gospel” in tracking his progress. While the heart failure diagnosis changed his life, Mike said his new regimen is a small price to pay to stay alive.

“If someone told you, you had to do this to live,” he said, “wouldn’t you live?”