What are the most common adverse events in healthcare and how are they prevented?

September 26, 2025 •

4 min read

According to research published in the New England Journal of Medicine, nearly one in four hospital patients experienced an adverse event during their stay. Understanding what are the most common adverse events is a critical first step for both patients and healthcare professionals aiming to improve overall safety and care quality.

Quick Summary

The most frequently identified adverse events in healthcare include adverse drug events, surgical complications, patient-care incidents such as falls and pressure ulcers, and healthcare-associated infections.

Key Points

Common Event Types: The most frequent adverse events involve medication errors, surgical mishaps, patient falls, and healthcare-acquired infections.
Drug Events Dominate: Adverse drug events, including both errors and unintended reactions, are a leading cause of patient harm in clinical settings.
Prevention is Key: Many adverse events are preventable through systematic improvements in communication, training, and technology.
AE vs. Side Effect: An adverse event is any negative incident, while a side effect is an adverse event proven to be caused by the medical intervention.
Cultivating Safety: Establishing a strong, non-punitive culture of safety is crucial for encouraging the reporting of mistakes and preventing future errors.
Role of Technology: Utilizing tools like CPOE and barcode systems can significantly mitigate the risk of medication-related adverse events.

Understanding the Landscape of Patient Safety

Adverse events are a significant concern within the healthcare system. They represent untoward incidents that can result in patient discomfort, injury, or even death. These events are not always preventable, but many result from human error or systemic failures. Understanding the different types, causes, and prevention methods is essential for creating a safer environment for everyone involved in the healthcare process.

The Most Common Categories of Adverse Events

Comprehensive studies have identified several key categories that account for the majority of incidents. By breaking down these areas, we can better target prevention efforts.

Adverse Drug Events (ADEs)

Medication-related incidents are consistently ranked among the most common adverse events. This category can be further divided into two main types:

Medication Errors: These are preventable events that occur due to a mistake in the medication process. This can involve prescribing the wrong drug or dose, dispensing an incorrect medication, or administering it at the wrong time or to the wrong patient. Barcode scanning and computerized physician order entry (CPOE) systems are two technological solutions that help reduce these risks.
Adverse Drug Reactions (ADRs): These are unintended and harmful reactions that occur even when a drug is used correctly. ADRs can range from mild side effects like nausea and fatigue to severe, life-threatening complications. They can be predictable (Type A, dose-dependent) or unpredictable (Type B, allergic reactions).

Surgical and Procedural Events

Events related to surgeries and other medical procedures constitute another large portion of adverse events. These can be particularly serious and may include:

Surgical Errors: These involve mistakes made during a procedure, such as wrong-site, wrong-procedure, or wrong-patient surgery. The National Quality Forum classifies these as "never events" due to their preventability.
Retained Foreign Objects: Leaving surgical tools or sponges inside a patient after a procedure is a grave and preventable error.
Post-Procedural Complications: This includes complications like air embolisms from medical devices or other unintended outcomes following a procedure.

Patient-Care Events and Hospital-Associated Infections (HAIs)

General patient care also carries risks that can lead to adverse events. These often involve basic care protocols and environmental factors.

Patient Falls: Falls within a healthcare setting are a leading cause of preventable harm, often resulting in fractures, head injuries, and other trauma. Risk factors include advanced age, medication use, and underlying health conditions.
Pressure Ulcers: Also known as bedsores, these are preventable injuries to the skin and underlying tissue resulting from prolonged pressure. Proper patient mobility and frequent repositioning are crucial for prevention.
Healthcare-Associated Infections (HAIs): These are infections acquired while receiving treatment for other conditions. Common examples include catheter-associated urinary tract infections (CAUTIs) and central line-associated bloodstream infections (CLABSIs). Strict infection control measures are necessary to combat these.

Adverse Event vs. Side Effect: A Crucial Distinction

It is important for both patients and healthcare providers to distinguish between an adverse event and a side effect, as the terms are often used interchangeably but have different meanings.


Feature	Adverse Event	Side Effect
Definition	Any untoward or undesirable incident associated with a medical intervention.	An adverse event that is actually caused by the medical intervention.
Causality	No causal link to the medical intervention is required. Could be related or entirely coincidental.	A known or proven causal link exists between the intervention and the effect.
Predictability	Can be predictable or unpredictable. Includes things like falls or surgical errors.	Generally predictable and related to the known pharmacology of a drug.
Reporting	All incidents must be reported, even if the link to the treatment is unclear.	Part of the expected risk profile of a medication, though serious ones are reported.
Example	A flu shot recipient gets in a car accident later that day. It is an AE, but not a side effect.	A flu shot recipient experiences a sore arm. This is a known side effect.

Strategies for Preventing Adverse Events

Preventing adverse events requires a multi-faceted approach focusing on systemic changes rather than individual blame. Healthcare organizations can implement several strategies to enhance patient safety.

Establish a Culture of Safety: Leaders must foster an environment where open communication and error reporting are encouraged without fear of retribution. This allows for honest analysis and correction of systemic problems.
Implement Effective Communication Protocols: Miscommunication is a common root cause of errors. Standardized hand-off procedures and clear documentation help ensure that critical patient information is accurately transferred between healthcare professionals.
Enhance Staff Training and Education: Continuous education and training for healthcare staff on topics like medication safety, infection control, and patient identification are essential to maintain high standards of care.
Leverage Technology for Patient Safety: Utilizing electronic health records (EHRs), CPOE, and barcode scanning systems can significantly reduce the risk of medication and identification errors.
Conduct Regular Risk Assessments: Proactively assessing potential hazards and vulnerabilities within the healthcare setting helps organizations implement preventive measures before incidents occur.
Encourage Patient Engagement: Involving patients in their own care and empowering them to ask questions can act as an important safety check and reduce the likelihood of incidents.

Conclusion: The Path to Safer Healthcare

Adverse events remain a challenging reality in healthcare, but they are not an insurmountable problem. By understanding what are the most common adverse events—from drug-related complications to surgical errors and patient falls—we can better appreciate the scope of the issue. The path forward lies in a comprehensive approach: fostering a culture of safety, improving communication and training, leveraging technology, and engaging both staff and patients in the process. Continuous monitoring and evaluation, as highlighted by sources like NCBI StatPearls, are vital to ensuring sustainable improvements and building a safer healthcare system for all.

Frequently Asked Questions

An adverse event is any undesirable incident that occurs, regardless of its cause. A side effect is a specific type of adverse event that is known to be caused by a medical intervention, such as a medication or vaccine.

No, not all adverse events are preventable, as some may be a known risk of treatment. However, many adverse events, such as those caused by medication errors or surgical mishaps, are considered preventable.

Common examples of adverse drug events include medication errors (wrong drug, dose, or patient) and unintended side effects, such as allergic reactions, nausea, dizziness, or abnormal heart rhythms.

Technology, such as computerized physician order entry (CPOE), electronic health records, and barcode scanning, can reduce errors by providing alerts for drug interactions and ensuring the right medication is given to the right patient.

Everyone from healthcare professionals to patients can report adverse events to the relevant authorities. Manufacturers of drugs and devices are also required to report such incidents to regulatory bodies like the FDA.

Healthcare-associated infections are infections that a patient acquires while receiving medical treatment, often preventable through strict adherence to hygiene protocols and infection control measures.

A sentinel event is a type of adverse event that results in death, major permanent loss of function, or significant injury. These events are so serious that they require immediate investigation and response.