Can You Get A DUI From Prescription Medication?

Barnes & Fersten Law Firm

Barnes & Fersten Law Firm

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Woman taking prescription medication in her car

Have you ever wondered if taking your prescribed medication could put you at risk of a DUI charge? Many Tennessee residents are aware that driving under the influence of alcohol or illegal drugs could lead to a DUI, but few consider the legal implications of prescription medications. In this blog we’ll delve into the details, from the types of medications that can get you into trouble on the road, how authorities determine impairment, and the potential defenses you might have.

Prescription Medications and Tennessee DUI Laws

The term DUI often brings to mind scenarios involving alcohol. But did you know that the law includes substances beyond just alcohol, including prescription medications? Let’s delve into how prescription medications play into the DUI framework in Tennessee.

The Broad Scope of Tennessee DUI Laws

A DUI charge in Tennessee centers around impairment. By law, individuals are prohibited from operating a vehicle:

  • With a blood alcohol content (BAC) of 0.08% or higher
  • While under the influence of any intoxicant, narcotic drug, or drug producing stimulating effects on the central nervous system

Beyond the well-known restrictions on alcohol, Tennessee’s DUI laws also encompass a range of other substances. This includes prescription medications that have the potential to affect your motor skills, reaction times, and cognitive functions. In short, the question becomes whether the prescription medication effected your clearness of mind and consequently your ability to operate a motor vehicle. While it’s not illegal per se to take prescription medications and drive in Tennessee, you could land a DUI charge if those medications impair your driving abilities. It doesn’t matter if you’ve been prescribed the medication or if you’ve taken it as directed; the emphasis lies on any resultant impairment.

Unlike alcohol, which has a clear BAC threshold to determine intoxication, there isn’t a specific drug concentration that signifies impairment. Thus, DUI cases involving prescription medications often rely on officer observations, field sobriety tests, and expert witness testimonies. Keep in mind that many prescription drugs come with cautionary labels advising against tasks like operating machinery or driving. If you opt to drive after consuming a medication bearing such a warning, it could be cited against you during a DUI case.

Types of Prescription Medications That May Implicate DUI

While numerous prescription medications can affect driving ability, some are more commonly associated with DUI charges. Let’s dive into the types of prescription drugs that could put you at risk.

Sedatives and Tranquilizers

  • Examples: Benzodiazepines (like Valium, Xanax, and Ativan), certain sleep medications (like Ambien).
  • Effects: Can cause drowsiness, dizziness, slowed reaction time, and impaired judgment. Combining them with alcohol can amplify these effects.

Opioids and Pain Relievers

  • Examples: Codeine, Morphine, Oxycodone (OxyContin), Hydrocodone (Vicodin).
  • Effects: Beyond relieving pain, these can induce drowsiness, dizziness, and sedation. They can also impair cognitive functions and motor skills, especially when taken in large amounts or combined with other substances.


  • Examples: Amphetamines (like Adderall) and methylphenidates (like Ritalin).
  • Effects: While designed to increase alertness, focus, and energy, they can also lead to nervousness, agitation, increased heart rate, elevated blood pressure, and even aggressive behavior, impacting one’s ability to drive safely.


  • Examples: SSRIs (like Prozac and Zoloft), MAOIs, and tricyclics.
  • Effects: Some antidepressants can cause dizziness, fatigue, and blurred vision. While they help regulate mood, they can sometimes impair driving skills, especially during the initial phase of treatment or dosage changes.


  • Examples: Diphenhydramine (found in Benadryl), cetirizine (Zyrtec).
  • Effects: Commonly used for allergies, certain antihistamines can cause drowsiness and slow reaction time, particularly in older adults.


How Authorities Determine Impairment

When it comes to DUI charges, it’s not only about the presence of a substance in one’s system but its effect on one’s ability to drive safely. Given that prescription medications don’t have a straightforward impairment metric like the BAC for alcohol, the process for determining impairment can involve multiple steps. However, there are charts our attorneys use, the same charts toxicologists called on by the State rely upon, to determine the level of the medication in the blood. These measures cause the State’s experts to allege a defendant is likely to be impaired by a medication. Our attorneys have experience cross-examining and defending against State expert witnesses on allegations of drug impairment based on toxicology reports. State experts are not pharmacologists, they do not review client medical records or body camera footage to determine the likelihood that our client exhibited the intended effects and side effects of the medication to the point of causing any type of impairment.

Observational Skills During Traffic Stops

During a traffic stop, officers will assess a driver’s demeanor, coherence, eye movement, and physical coordination. Slurred speech, erratic behavior, or the inability to follow instructions can be indicative of impairment. The type of prescription medication will impact what indicators of impairment are observed such as potentially constricted or pinpoint pupils and lethargic movements and speech.

The way a driver responds to routine questions, their ability to maintain a conversation, and any observable physical unsteadiness can all serve as cues for officers to suspect impairment, prompting further tests.

Standard Field Sobriety Tests

These are a series of tests officers may administer roadside to assess a driver’s physical and cognitive functions. Standard field sobriety tests include the Horizontal Gaze Nystagmus (HGN), the Walk-and-Turn, and the One-Leg Stand tests.

It’s worth noting that while these tests can be effective for alcohol impairment, their accuracy for drug impairment, including prescription medications, can vary. However, they still serve as an essential tool for officers to gauge overall impairment. For example, many officers will allege that they observe HGN in a non-alcohol prescription medication DUI case when it may not be possible. Instead, the officer more than likely simply sees constricted pupils in such a case.

Blood and Urine Tests

If officers have probable cause to suspect drug-induced impairment, they may request a blood sample. These tests can detect the presence of drugs but may not directly correlate with the level of impairment, especially for prescription medications. As one may suspect, there are countless factors that go into whether the prescription medication is having an impairing effect such as the type of medication, tolerance, and medical history that all are important factors to review.

Timing is a crucial factor here. The body metabolizes drugs at different rates, meaning the concentration in one’s system might not align with the level of impairment at the time of driving. The expertise of toxicologists might be enlisted in court to interpret results by the State. However, the State’s expert generally will not review medical records to determine tolerance, nor will the toxicologist review the body camera footage to determine whether the side effects of the medication are observed to be present and therefore having its intended effects. Consequently, the State’s toxicologist expert generally will not have the ability to testify whether a defendant was or was not impaired. The expert can only speak in generalities that someone with that level in their blood may be impaired, potentially creating reasonable doubt in and of itself.

Drug Recognition Experts (DRE) and Advanced Roadside Impaired Driving Enforcement (ARIDE)

Some jurisdictions have officers specially trained as Drug Recognition Experts. DREs undergo extensive training to recognize impairment from various drugs, including prescription medications. Their evaluation can be comprehensive, considering both physiological and behavioral indicators.

DRE evaluations often encompass a series of steps, including an interview, eye examinations, psychophysical tests, and vital sign measurements. Their findings can significantly bolster the prosecution’s case in DUI charges involving drugs. DRE’s often use additional non-standardized field sobriety tests that are alleged to establish impairment based on drugs. Again, there are many shortages of these non-standardized tests and our lawyers have experience demonstrating those weaknesses.

Expert Witnesses in Court

In situations where the relationship between the drug’s presence and impairment is intricate, expert witnesses, like pharmacologists or toxicologists, may be called upon in court. They can provide insights into how certain medications might affect an individual and validate or challenge other evidence.

The testimony of these experts can play a pivotal role, especially when dealing with medications that have varying effects on different individuals or when considering factors like tolerance or drug interactions. In prescription medication cases we generally recommend utilizing an expert to establish that our client was likely not impaired by the medications. Because the State’s expert generally cannot specifically state whether our client is impaired based on the number in his or her blood, we use experts to review more than just the toxicology report. Our experts would give a wholistic expert evaluation base on all the evidence to the jury to demonstrate the State experts’ shortcomings.

Legal Defenses Against Prescription Medication DUI Charges

If you’ve been charged with a DUI due to the influence of prescription medications, it might feel like your options are limited. However, there are several legal defenses that you can employ, under the guidance of experienced Tennessee DUI attorneys, to challenge the charges against you.

Lack of Probable Cause for the Traffic Stop

One of the first elements scrutinized in a DUI case is whether the officer had probable cause to initiate the traffic stop. If it’s demonstrated that there was no reasonable basis for pulling you over, any evidence gathered during the stop may be inadmissible in court.

This defense strategy aims to undercut the foundational legality of the arrest, making subsequent evidence and observations irrelevant. Keep in mind that probable cause varies from case to case and requires nuanced legal analysis.

Challenging Field Sobriety Test Results

As we’ve discussed earlier, field sobriety tests are not foolproof, particularly when it comes to impairment from prescription medications. A skilled defense attorney can call into question the validity and reliability of these tests, especially if they were improperly administered or interpreted.

It’s important to consult experts who understand the limitations of these tests, as it can help in weakening the prosecution’s case.

Challenging Blood and Urine Test Results

Blood and urine tests can be tricky. Not only do they require proper handling and chain of custody, but they also demand precise interpretation. If any of these elements are compromised, the test results may be deemed unreliable.

Legal teams often engage forensic experts to scrutinize the methodology and interpretation of these tests, aiming to cast doubt on the link between the drug levels detected and actual impairment.

Involvement of Drug Recognition Experts (DRE)

Just as a DRE can strengthen the prosecution’s case, challenging their qualifications or findings can weaken it. If a DRE was involved, an experienced defense attorney will probe their training, experience, and methodology, potentially undermining their credibility.

The human element of DRE evaluation means that errors and biases can occur. By challenging the subjective aspects of their assessment, one may be able to tilt the scales of justice.

Don't Navigate Prescription DUIs Alone

If you find yourself in a situation involving a DUI and prescription medications, your first step should be to seek qualified legal advice. This is not an area where you want to cut corners; the implications are far too serious, and the potential penalties are severe.

With the right legal counsel, you have the opportunity to challenge the evidence, question the procedures followed during your arrest, and explore possible defenses. In such high-stakes matters, you need attorneys with a proven record in DUI and criminal defense law to stand by your side.

If you or a loved one are facing a DUI charge involving prescription medications, contact the Knoxville TN DUI attorneys at Barnes & Fersten for a consultation. We’re committed to providing you with the highest level of legal representation, guiding you through every step of the process.

Attorney At Law, Managing Partner

Brandon D. Fersten is an esteemed Knoxville attorney practicing DUIcriminal defense, and juvenile law. Known for his empathetic approach and commitment to his clients, he brings a record of favorable case outcomes including dismissals and not guilty verdicts at jury trials resulting in Brandon being recognized as one of the “Top 40 Under 40” in Criminal Defense, U.S. News’ Best Lawyers: “Ones to Watch,” and Super Lawyers’ “Rising Stars”. Brandon’s professional accolades, combined with his passion for justice, position him as a reliable criminal defense advocate in the East Tennessee legal landscape.