DUR stands for Drug Utilization Review, a systematic process pharmacies use to evaluate prescriptions against a patient’s medication history, allergies, and clinical guidelines before dispensing a drug. Rooted in a 1990 federal law, DUR is essentially a safety net built into every pharmacy’s workflow, designed to catch problems like dangerous drug interactions, incorrect dosing, and therapeutic duplication before a medication reaches your hands. The system is more complex than most patients realize, and it shapes everything from how long you wait at the pharmacy counter to how much your insurance plan pays for medications.
Where DUR Came From
The formal requirement for Drug Utilization Review traces back to the Omnibus Budget Reconciliation Act of 1990, commonly called OBRA ’90. That law mandated that every state Medicaid outpatient prescription program implement a DUR system, with full rollout by 1993. Under the mandate, pharmacists performing DUR must review past patterns of drug misuse, monitor current therapy, and offer patient counseling.1PubMed Central. A primer on drug utilization review While OBRA ’90 technically applied to Medicaid, the infrastructure it demanded quickly spread. Private insurers, pharmacy benefit managers, and hospital systems adopted DUR processes as standard practice. Today, virtually every pharmacy in the United States runs some form of computerized DUR screening on every prescription it fills, regardless of who is paying for the medication.
The Three Types of DUR
DUR comes in three flavors, distinguished by when the review happens relative to the patient receiving their medication.
- Prospective DUR: This is the real-time check that happens before you walk out of the pharmacy with your prescription. When a pharmacist or technician enters your prescription into the dispensing system, the software automatically screens it against your medication profile, allergy records, and clinical rules. If it finds a problem, it generates an alert the pharmacist must address before the prescription can be completed.
- Concurrent DUR: This occurs while a patient is actively receiving treatment, most commonly in hospital or long-term care settings. It involves ongoing monitoring of drug therapy during a course of treatment, checking that lab values, dosing adjustments, and therapeutic goals stay on track.
- Retrospective DUR: This is a backward-looking analysis performed after prescriptions have already been dispensed. Insurers and state Medicaid programs use retrospective DUR to scan large claims databases for patterns of inappropriate prescribing, identify providers or patients who may need intervention, and measure how well the overall system is working.
Of these three, prospective DUR has the most direct impact on the average pharmacy customer, because it is the one most likely to affect your experience at the counter.
How Prospective DUR Works at the Pharmacy
When your prescription is entered into a pharmacy’s dispensing system, the software runs your new medication against a set of clinical rules and your existing medication profile. These DUR alerts are triggered during the medication fill review process, which can occur during pharmacist clinical review of a first fill or during final verification of a single medication.2Journal of Infusion Nursing. Evaluation of Overridden Drug Utilization Review (DUR) Alerts in an Ambulatory Pharmacy Dispensing System: Patterns, Documentation Practices, and Opportunities for Optimization – Section: Methods The whole thing happens in seconds, often before you have finished browsing the store.
The types of problems the system screens for include drug-drug interactions, drug-allergy conflicts, therapeutic duplication (two medications doing the same job), inappropriate dosing based on age or weight, and drug-disease contraindications. If any of these rules are triggered, an alert pops up on the pharmacist’s screen. The pharmacist then decides whether the alert represents a genuine safety concern or a clinically acceptable situation the prescriber already accounted for.
Computer-assisted prospective DUR systems have become a standard component of pharmacy practice, and they have clearly demonstrated their ability to improve the quality and safety of medication delivery.3PubMed Central. Improving Clinical Decision Support in Pharmacy: Toward the Perfect DUR Alert But as we will see, the technology has some significant growing pains.
What the Alerts Actually Catch
The screening categories built into DUR systems cover a surprisingly wide range of potential problems. Drug-drug interaction alerts are among the most common and most studied. These flag situations where two medications a patient is taking could interact in harmful ways, such as one drug amplifying the side effects of another or reducing its effectiveness. Some pharmacy systems present these alerts differently depending on severity, including hard stops for the most dangerous interactions that prevent the pharmacist from proceeding without specific action.4PubMed Central. Tiering drug-drug interaction alerts by severity increases compliance rates
Therapeutic duplication alerts flag situations where a patient may be receiving two medications from the same drug class. In a Dutch study of community pharmacy alerts, clinical decision support systems generated about 20 duplicate medication alerts per 100 dispensed drugs. In roughly half of those alerts, pharmacists judged there was no risk from concurrent use. In about a third, the duplication was an intentional combination prescribed on purpose. But in 17% of alerts, there was a real risk of unintentional concurrent use, and in about a third of all alerts, pharmacists decided that some action was needed, whether updating the patient record, informing the patient, or modifying the prescription.5PubMed Central. Nature and management of duplicate medication alerts That 17% figure matters: even after filtering out the noise, a meaningful fraction of duplicate alerts identify genuine problems that could hurt a patient if left uncorrected.
Drug-allergy alerts cross-reference a new prescription against allergies recorded in your pharmacy profile. If you have a documented penicillin allergy and a prescriber sends in an antibiotic from the same family, the system will flag it. Drug-food interaction alerts warn about medications whose absorption or metabolism is significantly affected by certain foods, such as grapefruit juice interacting with certain cholesterol-lowering drugs. Dosing alerts flag prescriptions where the dose falls outside established ranges for the patient’s age, weight, or kidney function.
The Alert Fatigue Problem
Here is where DUR systems run into their biggest real-world limitation. The sheer volume of alerts pharmacists face every day is enormous, and most of those alerts do not represent genuine safety threats. In one study of an ambulatory pharmacy dispensing system, over 93,000 alerts were overridden by 73 pharmacists in just three months, covering more than 16,600 patients. The most common alert types were duplicate therapy (about 36%), drug-food interactions (about 29%), and drug-allergy alerts (about 24%).6Journal of Infusion Nursing. Evaluation of Overridden Drug Utilization Review (DUR) Alerts in an Ambulatory Pharmacy Dispensing System: Patterns, Documentation Practices, and Opportunities for Optimization
When nearly every prescription triggers a pop-up, pharmacists start clicking through alerts out of habit. This is alert fatigue, and it is a well-documented threat to patient safety. The DUR system often generates low-level alerts, making it difficult for pharmacists to distinguish the critical ones from the routine noise. The result can be burnout and, paradoxically, reduced safety, because important warnings get lost in the flood.7PubMed Central. Pharmacists’ Perceptions on Safety Alerts of the Drug Utilization Review (DUR) in Electronic Health Records in a Tertiary Healthcare Hospital
In one survey of pharmacists at a hospital, 85% had experience with DUR alerts, but 40% expressed dissatisfaction with the system. While 88% reported receiving highly frequent alerts, only 40% believed the alerts could identify rare adverse drug reactions. And just 27% of pharmacists said they altered prescriptions based on alerts for certain high-risk drug combinations like MAO inhibitors with serotonin modulators.7PubMed Central. Pharmacists’ Perceptions on Safety Alerts of the Drug Utilization Review (DUR) in Electronic Health Records in a Tertiary Healthcare Hospital That disconnect between alert volume and pharmacist action is the central tension in modern DUR system design. The technology catches problems, but if it cries wolf too often, the people who need to act on its warnings start tuning it out.
Why So Many Alerts Get Overridden
The high override rate does not necessarily mean pharmacists are being reckless. In many cases, an alert fires for a situation the prescriber and pharmacist are already aware of. A patient on two blood pressure medications from similar classes might be on that combination intentionally, under careful monitoring. A drug-allergy alert might fire because a patient had a mild rash from a related medication decades ago, and the prescriber has already weighed the risk.
The documentation practices around overrides are a concern, though. In the ambulatory pharmacy study, the most common override response was simply “Clinician Reviewed,” used about 89% of the time. Only 1.2% of overridden drug-drug interaction alerts, all of which were classified as severe or contraindicated, had accompanying free-text comments explaining why the pharmacist overrode the alert.6Journal of Infusion Nursing. Evaluation of Overridden Drug Utilization Review (DUR) Alerts in an Ambulatory Pharmacy Dispensing System: Patterns, Documentation Practices, and Opportunities for Optimization That means almost no one is recording their reasoning when they dismiss even the most serious warnings. If something goes wrong later, there is no trail showing the pharmacist actually evaluated the specific clinical situation. This is one of the areas where DUR systems have the most room for improvement.
The Knowledge Bases Behind the Screens
DUR alerts do not come from thin air. They are powered by commercial clinical knowledge bases, essentially massive databases of drug information that encode rules about interactions, contraindications, dosing limits, and more. In the United States, the three dominant knowledge bases are First DataBank (FDB), Micromedex, and Multum. Different pharmacy systems and electronic health records may use different knowledge bases, which means the alerts a pharmacist sees can vary depending on which system their pharmacy runs.8PubMed Central. Comparison of three commercial knowledge bases for detection of drug-drug interactions in clinical decision support
This is more than a technical curiosity. When researchers compared these three knowledge bases, they found meaningful differences in what each one flagged. Different knowledge bases mapped drugs to standard identifiers in different ways and applied different sets of interaction rules. The Office of the National Coordinator for Health Information Technology has published a reference list of highly significant drug-drug interactions, and the three knowledge bases did not perform identically when measured against it.9Journal of the American Medical Informatics Association. Comparison of three commercial knowledge bases for detection of drug-drug interactions in clinical decision support The practical implication: a dangerous interaction flagged at one pharmacy might not be flagged at another if the two use different software vendors. This inconsistency is an active area of concern among patient safety researchers.
Retrospective DUR and the Bigger Data Picture
While prospective DUR operates at the individual prescription level, retrospective DUR zooms out to the population level. State Medicaid programs, insurers, and pharmacy benefit managers analyze large claims databases after prescriptions have been filled, looking for patterns that suggest problems. One large retrospective DUR analysis examined a database of roughly 2.9 million patients and more than 30 million prescriptions dispensed over a 12-month period, using computerized triggers to detect 69 prespecified serious drug-drug interactions.10PubMed Central. Retrospective drug utilization review: incidence of clinically relevant potential drug-drug interactions in a large ambulatory population
These analyses serve a different purpose than real-time alerts. They help identify prescribers who may have unusual or potentially harmful prescribing patterns, patients who may be receiving medications from multiple providers without coordination, and systemic issues with how certain drug classes are being used across a health plan. One study that examined whether retrospective DUR programs actually reduced prescribing errors looked at state Medicaid data aligned around each program’s implementation date, searching for a drop in the rate of problematic prescriptions after the program went live.11JAMA. Retrospective Drug Utilization Review, Prescribing Errors, and Clinical Outcomes The question of whether retrospective DUR meaningfully changes prescribing behavior at scale remains an active research question, with the evidence being somewhat mixed depending on the program design and the outcomes measured.
DUR and Controlled Substances
DUR takes on special significance when it comes to controlled substances like opioids and benzodiazepines. Prescription drug monitoring programs, which are a specialized form of DUR, track prescriptions for controlled substances across providers and pharmacies. These systems can identify patients receiving overlapping prescriptions from multiple providers and flag providers with unusual prescribing patterns.
In one state-level analysis, researchers developed algorithms to identify providers whose prescribing practices stood out as unusual. The metrics that showed the strongest validity related to providers who co-prescribed benzodiazepines with high levels of opioid analgesics, and those who wrote temporally overlapping prescriptions. These patterns were cross-validated against death records for patients who died of a medication or drug overdose within 30 days of receiving a prescription.12PubMed. Using one state’s prescription drug monitoring program to develop algorithms to identify providers with unusual prescribing practices for controlled substances The combination of benzodiazepines and opioids is one of the most dangerous drug combinations in clinical practice, and DUR-type systems are one of the primary tools regulators use to identify it before it leads to patient harm.
How States Measure DUR Cost Savings
Every state Medicaid program is required to measure the cost savings generated by its DUR programs, but there is no standardized way to do it. The Centers for Medicare and Medicaid Services requires the annual measurement but provides no unified methodology. In 2014, the most commonly used method for measuring retrospective DUR savings was a simple before-and-after comparison with no comparison group. By 2015, the most common approach had shifted to a before-and-after method that included a comparison group.13PubMed Central. Comparing the Medicaid Retrospective Drug Utilization Review Program Cost-Savings Methods Used by State Agencies
For prospective DUR, the most common approach in 2015 and 2016 was calculating total claim rejections and subtracting resubmissions at the amount actually paid. Eighteen states used this method.14PubMed Central. Comparing the Medicaid Prospective Drug Utilization Review Program Cost-Savings Methods Used by State Agencies in 2015 and 2016 The reported savings numbers are substantial. Depending on which methodology states used, the collective savings ran into hundreds of millions of dollars per year, with individual state averages ranging from roughly $43 million to $109 million per year.15American Health & Drug Benefits. Comparing the Medicaid Prospective Drug Utilization Review Program Cost-Savings Methods Used by State Agencies in 2015 and 2016
Those numbers come with a major caveat. Because each state uses a different calculation method, direct comparisons between states are unreliable. A state reporting $100 million in savings might be measuring something fundamentally different from a neighboring state reporting $50 million. The lack of standardization makes it hard to know how much DUR programs save in aggregate across the country, even though the available data suggest the savings are real and substantial.
What DUR Means for You at the Pharmacy Counter
If you have ever been told at the pharmacy that your prescription needs “additional review” or that the pharmacist needs to call your doctor, there is a good chance a DUR alert was involved. Sometimes the alert is resolved quickly. Other times, especially when a potential drug interaction or duplicate therapy is flagged, the pharmacist may need to contact the prescriber to clarify the intent, which can add 15 minutes or several hours to your wait depending on how quickly the prescriber’s office responds.
The system also affects which prescriptions your insurance will cover. Pharmacy benefit managers use DUR criteria as part of their claims adjudication process. When you submit a prescription through insurance, the claim runs through DUR edits in real time. Certain combinations or quantities may trigger a “hard reject” at the insurance level, requiring prior authorization before the claim can go through. This is different from the clinical DUR the pharmacist performs, though both happen in the same workflow and can feel indistinguishable from the patient’s perspective.
You can help the system work better for you by keeping your medication and allergy records up to date at every pharmacy you use. If you fill prescriptions at multiple pharmacies, each one may have an incomplete picture of your medication profile, which means some interactions could slip through the cracks while others trigger unnecessary alerts. Consolidating your prescriptions at a single pharmacy, or at least making sure each pharmacy has your complete medication list, gives the DUR system the best chance of catching real problems while generating fewer false alarms.
Where DUR Systems Are Headed
The gap between what DUR systems promise and what they deliver in daily practice is well recognized. Researchers have noted that while computer-assisted prospective DUR systems have clearly improved the safety of medication delivery, they have yet to fully achieve their promised potential.3PubMed Central. Improving Clinical Decision Support in Pharmacy: Toward the Perfect DUR Alert The biggest areas of active development involve making alerts smarter and less noisy. Severity-tiered alerts, which present warnings differently based on how dangerous the interaction is, have already shown improvements in how often clinicians follow through on high-priority warnings.4PubMed Central. Tiering drug-drug interaction alerts by severity increases compliance rates
Other efforts focus on incorporating more patient-specific data into alerts. A system that knows your actual kidney function, lab values, and genetic profile could generate far more targeted warnings than one that only knows your age and medication list. Integration of pharmacogenomic data, where a patient’s genetic makeup influences how they metabolize certain drugs, represents one of the more ambitious frontiers. The challenge is mostly about data infrastructure and interoperability rather than the underlying science, since the clinical knowledge already exists for many gene-drug interactions but getting that information into the right software system at the right moment remains technically difficult. For now, the pharmacy DUR system you encounter is a powerful but imperfect tool that catches a meaningful number of genuine safety issues while generating a frustrating amount of noise in the process.