A patient receives twice the prescribed dose of insulin. Another is given a medication intended for someone in the next hospital bed. A third misses an important antibiotic treatment because an order was entered incorrectly.
Medication errors can happen at almost any stage of hospital care. Some are caught before reaching patients. Others cause serious complications, longer hospital stays, and occasionally death.
The Agency for Healthcare Research and Quality (AHRQ) has documented hundreds of thousands of medication-related safety reports across American healthcare facilities. Its findings identify incorrect doses, medication administration mistakes, and prescribing errors among the major problems affecting patient safety.
How Common Are Medication Errors in US Hospitals?
The AHRQ medication safety chartbook includes 486,543 reports involving medications or other substances submitted to the National Patient Safety Database.
Medication-related events accounted for 25% of all patient safety events reported to the database. However, the figures come from participating reporting systems and should not be interpreted as the total number of medication errors occurring in American hospitals.
Among reports with enough information to identify the stage where a problem began, about 36% originated during medication administration. Another 27% began during prescribing.
| Medication Safety Finding | Reported Figure |
|---|---|
| Medication and other substance event reports | 486,543 |
| Share of all reported patient safety events | 25% |
| Events originating during administration | 36% |
| Events originating during prescribing | 27% |
| Reported incorrect-action incidents resulting in harm | 5.5% |
The percentages use different subsets of reported events and cannot be added together. They also describe medication and other substance safety reports rather than a nationally representative sample of all hospital patients.
A separate investigation by the Department of Health and Human Services found that medication-related problems accounted for 43% of harmful events identified among hospitalized Medicare patients. Some involved preventable errors, but others resulted from drug reactions or complications that could not necessarily have been avoided.
1. Giving Patients the Wrong Medication Dose
Incorrect dosing is one of the most frequently reported medication mistakes. A patient may receive too much medicine, too little, or the correct amount at the wrong frequency.
The consequences depend heavily on the drug involved.
Too much insulin can cause blood sugar to fall dangerously low. Excessive blood thinner doses increase the risk of serious bleeding. Too little antibiotic treatment may leave an infection inadequately controlled.
Errors can begin with a prescription, an incorrect calculation, or confusion between different medication strengths.
Medication doses also depend on patient characteristics. Kidney function, body weight, age, and other prescribed drugs can affect how much medicine a person should receive.
The AHRQ review of medication errors identifies prescribing mistakes, incorrect administration, and problems monitoring treatment as important sources of preventable harm.
2. Giving Medicine to the Wrong Patient
Hospitals may have several patients receiving similar treatments in nearby rooms. Confusion can occur when staff rely on room numbers, incomplete records, or assumptions about patient identity.
Two patients might share similar names. A medication prepared for one person could accidentally be administered to another.
Some medicines can cause serious harm even after a single incorrect dose. Insulin, powerful pain medications, and drugs affecting blood clotting are particularly concerning.
Hospitals use identification wristbands and electronic medication records to reduce these risks. Staff should confirm patient identity using at least two approved identifiers before administering medication.
Room numbers alone are not reliable identifiers because patients can be moved during their hospital stay.
3. Missing a Dose or Giving Medication Too Late
Hospital treatment sometimes depends on medication arriving at the correct time.
A missed dose of an antibiotic can interrupt treatment. Delayed anti-seizure medication may increase the risk of a seizure in some patients. Missing prescribed insulin can contribute to dangerous blood sugar changes.
Scheduling mistakes can occur during shift changes, transfers between hospital departments, or periods when staff are handling multiple emergencies.
Not every late dose creates the same danger. A medication given 30 minutes behind schedule may have little clinical effect in one situation and serious consequences in another.
Hospitals therefore need to identify which medications require especially strict administration schedules.
4. Prescribing a Drug That Interacts With Another Medication
Patients admitted to hospitals frequently take several medications at the same time. Some arrive with prescriptions from different doctors, increasing the possibility of overlooked interactions.
For example, combining certain blood thinners with other medicines can increase bleeding risk. Some sedatives can produce dangerous respiratory effects when taken alongside opioids.
Drug interactions are not always prescribing errors. Doctors sometimes use interacting medicines deliberately when the expected benefits justify the risks and patients receive appropriate monitoring.
Problems arise when clinicians overlook an interaction, fail to adjust a dose, or miss a warning in the medical record.
Hospital pharmacists help review prescriptions and identify combinations that require changes or closer observation.
5. Medication Errors Involving Allergies
A patient with a documented severe allergy should not receive the medication responsible for that reaction without a medically justified reason and appropriate safeguards.
Yet allergy information can be missing, entered incorrectly, or overlooked during a hospital admission.
Some allergic reactions cause relatively mild symptoms, including itching or a rash. Severe reactions can produce breathing difficulties, dangerously low blood pressure, and anaphylaxis.
Patients should tell hospital staff about previous medication reactions and describe what happened. An upset stomach after taking a drug, for example, is different from a severe allergic reaction.
Accurate descriptions help clinicians determine which medications are unsafe and which side effects require monitoring.
6. Mistakes With High-Risk Medications
Some drugs require additional safeguards because even a relatively small error can cause serious injury.
The AHRQ medication administration guidance identifies anticoagulants, insulin, opioids, and chemotherapy medicines as examples of drugs that require particular attention.
| Medication Type | Potential Error | Possible Consequence |
|---|---|---|
| Insulin | Excessive dose | Severe hypoglycemia |
| Anticoagulants | Incorrect dose or monitoring | Major bleeding |
| Opioids | Excessive dose or unsafe combination | Respiratory depression |
| Chemotherapy | Incorrect calculation or administration | Serious organ or tissue injury |
| Intravenous potassium | Incorrect concentration or administration rate | Dangerous heart rhythm abnormalities |
Antibiotics also require careful prescribing and monitoring. Some can affect kidney function or cause neurological complications in vulnerable patients. Research into the hospital antibiotic cefepime and its potential safety risks illustrates the importance of weighing medication benefits against possible harm.
Hospitals may use additional checks, standardized concentrations, and electronic alerts for medications with greater potential to cause injury.
7. Errors During Hospital Transfers and Discharge
Medication lists can change several times during a hospital stay. Doctors may stop existing prescriptions, introduce new treatments, or adjust doses following surgery.
Problems arise when information does not follow the patient between departments or when discharge instructions differ from the final medication orders.
A patient might accidentally continue a medication that should have been discontinued. Another might leave the hospital without an important new prescription.
Medication reconciliation helps prevent such mistakes. Healthcare professionals compare existing medications with new orders and resolve differences before treatment continues.
The process is particularly important for patients taking multiple prescriptions or receiving care from several specialists.
What Happens When a Medication Error Causes Serious Harm?
A medication error can result in additional treatment, longer hospitalization, permanent injury, or death. However, the presence of an error does not automatically establish that medical malpractice occurred.
Healthcare providers must meet accepted standards of care. A legal claim generally requires evidence that a provider failed to meet the applicable standard and that the failure caused injury.
Medical records, medication administration logs, pharmacy orders, and laboratory results may help establish what happened.
Attorneys experienced in medical negligence cases, such as attorney Dan Hodes, work with patients and families dealing with injuries that may have resulted from improper medical care.
The distinction between a preventable error and an unavoidable complication matters because even correctly prescribed and administered medications can cause serious adverse reactions.
Why Medication Errors Are Not Always Reported
Hospital incident reports provide valuable safety information, but they do not capture every medication mistake.
Some errors go unnoticed. Others are corrected before reaching patients, and staff may not always report incidents that cause no obvious injury.
A federal review of hospital patient harm found significant problems with identifying and recording adverse events. Investigators reported that hospitals failed to capture about half of the patient harm events identified during a separate review.
Incomplete reporting can make it difficult to compare hospitals or determine how frequently particular mistakes occur.
Reported error counts also depend on how actively a hospital identifies incidents. A facility with more reports is not automatically less safe than one reporting fewer problems.
How Hospitals Can Reduce Medication Mistakes
Medication safety depends on reliable procedures throughout prescribing, preparation, administration, and monitoring.
- Electronic prescribing. Computerized orders reduce problems associated with illegible handwriting and can flag unsafe doses or drug interactions.
- Barcode scanning. Scanning patient wristbands and medication packaging helps confirm that the correct drug reaches the intended patient.
- Pharmacist review. Pharmacists can identify dosing mistakes, duplicate prescriptions, and potentially dangerous combinations.
- Additional safeguards for high-risk drugs. Standardized procedures and independent checks can reduce serious mistakes involving insulin, anticoagulants, and other hazardous medications.
- Medication reconciliation. Reviewing prescriptions during admission, transfers, and discharge helps prevent omitted or duplicated treatment.
- Clear patient communication. Explaining medication names, purposes, and expected effects gives patients another opportunity to recognize unexpected changes.
Patients can also ask questions when a medication looks unfamiliar or the prescribed dose appears different from what they previously received. A concern should be raised with the nurse, doctor, or pharmacist before the medicine is taken.
The most important finding in federal medication safety research is that mistakes can occur throughout the treatment process. Preventing harm depends on identifying problems before medications reach patients and responding quickly when an error occurs.
