Adverse drug events: Identifying risks and preventing harm

Medications are meant to help you feel better—but sometimes, they can do more harm than good. Adverse drug events (ADEs) can happen to anyone, regardless of age or health status, and they range from mild side effects to severe, life-threatening reactions. More than 1.5 million people visit emergency rooms for ADEs each year in the United States, and almost 500,000 require hospitalization, according to the Centers for Disease Control and Prevention (CDC).

Following your doctor’s instructions or reading the label may seem like enough to prevent harm—but medications don’t always work the same way for everyone. Factors like drug interactions, incorrect dosages, allergic reactions, and even your genetic profile can influence how a medication works for you, said Sara Rogers, PharmD, clinical assistant professor of precision medicine and ambulatory care at the Texas A&M University College of Medicine.

Rogers explains that adverse drug events occur more often than people realize and can have serious consequences. Whether you’re managing a chronic condition, recovering from an illness, or simply taking an over-the-counter remedy, understanding how drugs affect your body can help you stay safe.

What is an adverse drug event?

An adverse drug event (ADE) is an unintended and harmful reaction caused by a medication. These events range from mild side effects, such as nausea or dizziness, to severe complications, including organ damage or life-threatening allergic reactions. A specific type of ADE, known as an adverse drug reaction (ADR), occurs when a drug causes harm despite being taken correctly at the prescribed dose. However, not all ADEs are ADRs—some ADEs result from preventable factors like dosing errors, drug interactions or misuse.

Rogers said ADEs can occur for various reasons, including incorrect dosage, drug interactions or individual differences in how a person’s body metabolizes a medication. While many ADEs are preventable, they remain a significant, sometimes unpredictable, public health concern.

“An adverse drug event is really any kind of harm caused from taking a medication,” Rogers said. “There are a few different types of things that can cause an adverse drug event, with overdoses being one of the most well-known. But taking too much of a medication, whether intentionally or unintentionally, can lead to harmful side effects or even death.”

Recognizing symptoms of an ADE

ADEs can happen in various situations, often when there is a change in medication or how it is taken. Symptoms may present immediately after taking a medication or develop over time, depending on the nature of the drug and how a person’s body responds to it. Understanding these scenarios can help patients and health care providers anticipate and prevent potential issues.

“If your doctor is prescribing a medication, and they prescribe the wrong dose by accident or anything happens where you don’t receive the right drug, that can be a medication error that can lead to an adverse event,” Rogers said.

Common side effects include upset stomach, dry mouth and drowsiness. More severe reactions may involve difficulty breathing, swelling, rashes or anaphylaxis, which requires immediate medical attention. Chronic ADEs, such as liver or kidney damage, often develop gradually and may only become apparent through routine medical testing.

Drug interactions

A key factor in ADEs is polypharmacy, which occurs when a person takes multiple medications simultaneously. This is especially common among older adults and patients with chronic conditions. The likelihood of drug interactions increases as more medications are introduced into a patient’s regimen, Rogers said, potentially leading to unexpected side effects. Some drugs can amplify or weaken the effects of others, creating complications that might not be immediately noticeable.

“The three high-risk groups are children, older adults and anyone taking multiple medications. Children don’t really process medications the same way as they would when they’re an adult, which may impact their medication dosage, and older adults are at risk because, as we age, we tend to take more medications,” Rogers said.

Rogers explained that certain blood pressure medications, for example, can cause dangerous drops in blood pressure when combined with other prescriptions, leading to fainting or falls. Physicians and pharmacists play a critical role in monitoring these interactions, but patients should also stay informed about the medications they are prescribed and report any unusual symptoms.

“Let it be a flag in your mind to ask, could this have been the medication? Discuss it with your doctor and then, in addition to that, we recommend reporting it,” Rogers said.

The importance of monitoring and reporting ADEs

Monitoring and reporting ADEs help regulatory agencies improve drug safety. When patients experience unexpected or severe reactions, Rogers recommends communicating it with their health care provider as soon as possible. In some cases, alternative medications may be necessary, she said, or additional tests may be required to determine the cause of the reaction.

Regulatory agencies, such as the U.S. Food and Drug Administration (FDA), track reported ADEs to identify patterns and potential safety concerns with specific medications. This information helps inform future prescribing guidelines and ensures that new drugs undergo thorough safety evaluations before becoming widely available, Rogers said.

“There are safety surveillance programs like MedWatch for reporting side effects that weren’t identified during the drug trials that the risk may outweigh the benefit. So, if you go to FDA MedWatch, you can submit exactly what happened to you,” Rogers said.

Adverse drug events can affect anyone, which is why Rogers advocates for awareness and improved communication between health care providers and patients. Understanding side effects, recognizing warning signs, and reporting reactions can help reduce risks associated with medications.