Generic drugs can really save patients money. But when several companies make the same medication, their pills often look different, and that can be a problem, a study of medications prescribed for heart patients has found.

Patients who take the same pill every day may become confused or concerned when the pill they hold in the palm of their hand looks different. They may think the pharmacy has given them the wrong drug or the wrong dose and stop taking the drugs they have been prescribed.

When the patient is someone recovering from a heart attack, this can have life-threatening consequences.

Patients can help reduce the number of medication variations by filling prescriptions consistently at the same pharmacy.

“Changes in appearance can cause patients to lose confidence in the safety or effectiveness of their prescription drugs,” the Brigham and Women's Hospital researchers write. These changes in appearance can also contribute to dangerous errors such as taking the same medication twice without knowing it.

Researchers reviewed medical and pharmacy records of over 11,000 patients discharged from the hospital after a myocardial infarction (MI) or heart attack. Each patient had been prescribed generic versions of one or more of three classes of cardiovascular drugs within 90 days of leaving the hospital.

About a third of the patients had a pill change shape or color during the study, with statins having the most variations and beta-blockers the fewest. “Nonpersistence” — failure to continue taking medication — increased by 34% after a pill changed color.

“Cardiologists and other prescribers of cardiovascular medications should proactively warn patients about the potential changes and their lack of clinical importance,” the researchers say. These warnings are especially important because the use of generic heart drugs is becoming more and more common.

Patients can help reduce the number of medication variations by filling prescriptions consistently at the same pharmacy. Otherwise, if you use many pharmacies, where each may order from their own preferred suppliers, your medications may look different.

The study was published online recently in the Annals of Internal Medicine.