Can You Get a DWI for Taking Prescription Drugs in Texas? What Every Driver Must Know

What Texas Law Says About Prescription Drug DWI

Texas Penal Code §49.04 defines intoxication broadly. You’re considered intoxicated if you’ve taken any substance—including a prescribed medication—and your mental or physical faculties are impaired. The law doesn’t distinguish between illegal drugs, alcohol, and legally prescribed medications.

The key word is “impaired.” You could have prescription drugs in your system, but if your driving wasn’t actually affected, you shouldn’t be charged. Unfortunately, law enforcement doesn’t always see it that way, and proving you weren’t impaired requires a strong defense strategy.

The Dangerous Reality: The “Any Substance” Standard

Texas law is intentionally broad on this point. A substance doesn’t have to be illegal or even dangerous to trigger a DWI charge. Allergy medications, antidepressants, pain relievers, anti-anxiety drugs, sleep aids—all can be the basis for a DWI if an officer believes they impaired you.

What makes this especially troubling is that many prescription medications cause drowsiness, dizziness, or reduced reaction time as documented side effects. Your pharmacist may have warned you “don’t operate machinery” when filling your prescription. That warning doesn’t provide legal protection in Texas—it actually becomes evidence prosecutors use against you.

How Police Identify Prescription Drug Impairment

When an officer suspects you’re impaired but smells no alcohol, they have several tools at their disposal.

The DRE (Drug Recognition Expert) evaluation is the main one. DRE officers are trained to conduct a 12-step evaluation designed to identify drug impairment. They’ll test your pupils, check your vital signs, assess your muscle tone, and look for nystagmus (involuntary eye movement). They’ll have you perform field sobriety tests and may recommend a blood test to confirm the presence of drugs.

However, DRE evaluations are far from foolproof. The training is subjective, the science is questionable, and many DRE conclusions don’t hold up in court. Our attorneys know how to cross-examine DRE officers and expose weaknesses in their methodology.

Police will also look at your driving pattern. Did you drift between lanes? Drive too slowly? Make sudden stops? They’ll consider your appearance—bloodshot eyes, slurred speech, tremors. They may search your vehicle and find your prescription bottles, which they’ll use as evidence that you have access to impairing substances.

The Blood Test Problem

If police take your blood at the station or hospital, they’ll test it for drugs. Many commonly prescribed medications will show up on a standard drug screen. The problem: detecting a drug in your blood doesn’t prove you were impaired while driving.

Blood levels of prescription drugs can remain high long after any impairment has worn off. Someone might take their anxiety medication in the morning, be completely fine to drive by afternoon, yet still have detectable levels in their bloodstream if tested that evening. Prosecutors will use this against you, but our attorneys know how to present expert testimony about drug metabolism and the difference between presence and impairment.

Common Prescription Drugs That Lead to DWI Charges

• Benzodiazepines (Xanax, Valium, Ativan) are frequent culprits. These anti-anxiety and sleep medications can cause drowsiness, reduced coordination, and impaired judgment. They’re also commonly prescribed, so many Texas drivers take them.
• Opioid pain medications (Hydrocodone, Oxycodone, Morphine) are another major category. Even at prescribed dosages, they can cause dizziness, drowsiness, and reduced reaction time.
• ADHD medications (Adderall, Ritalin, Concerta) can cause increased heart rate, anxiety, and impaired judgment if someone takes more than prescribed or reacts unusually to the drug.
• Antidepressants like Zoloft, Lexapro, and Wellbutrin can cause dizziness, drowsiness, and impaired concentration—especially when first started or after dose changes.
• Antihistamines (Benadryl, Dramamine) are over-the-counter but can cause significant drowsiness and are a common basis for DWI charges.

Over-the-counter cold medicines containing dextromethorphan (DXM) can also result in impairment and DWI charges. The same applies to cannabis-related cases, where THC-based DWI charges depend heavily on how impairment is interpreted rather than just the presence of a substance.

The Critical Defense: You Have No Legal Defense That It Was Prescribed

Here’s something that shocks many defendants: it is not a legal defense that you took a medication exactly as prescribed. Texas law does not include a “prescribed medication” exception to DWI. Even if your doctor prescribed the medication, even if you took the exact dose recommended, even if the pharmacist said it was safe—none of that protects you from a DWI charge.

This is why having strong representation is essential. You can’t defend yourself by saying “my doctor told me to take this.” Instead, we must focus on whether the drug actually impaired you, whether police properly identified impairment, and whether the evidence meets the state’s burden of proof.

What to Expect if You’re Arrested for Prescription Drug DWI

Your arrest likely followed a traffic stop. An officer may have observed something minor—drifting lanes, expired registration, a broken taillight—and pulled you over. During the stop, they noticed signs they interpreted as impairment: slow speech, trembling hands, or difficulty with balance.

The officer will ask you to perform field sobriety tests (walk-and-turn, one-leg stand, horizontal gaze nystagmus). These tests are difficult for many people under normal circumstances and even more challenging if you’re nervous or have inner ear problems, balance issues, or previous injuries. Poor performance doesn’t prove impairment from drugs.

You’ll likely be arrested and taken to the police station or hospital for a blood test. You have the right to refuse this test in some circumstances, but refusing carries serious consequences in Texas, including automatic driver’s license suspension. Our attorneys can advise you on whether refusing was the right call in your specific situation.

After arrest, you’ll be booked, and your vehicle will be towed. You’ll either be released on bond or held pending a magistrate’s hearing. In Dallas County and surrounding areas, magistrate hearings typically happen within 24 hours.

Common Mistakes People Make in These Cases

• Talking to police without a lawyer. Many people think they can explain the situation—“I took my medication this morning, I felt fine to drive”—and the officer will understand. They won’t. Anything you say can and will be used against you. Remain silent and request a lawyer immediately.
• Agreeing to field sobriety tests. You’re not required to perform these tests, and the results are subjective. If you’re asked to perform them, you can politely decline. This is not the same as refusing a blood test, which has different legal consequences.
• Not challenging the blood test. How was the blood collected? Was it done properly? Was there a chain of custody? Was the lab certified? Was the test conducted correctly? Many DWI convictions are overturned because the blood test was flawed. Don’t assume the prosecution’s blood evidence is solid.
• Failing to consult a DWI specialist. These cases require specific knowledge about drug recognition, impairment standards, and DWI law. A general criminal defense attorney may not have the experience needed to effectively challenge the state’s evidence.

Your Defense Strategy: How Our Attorneys Challenge Prescription Drug DWI Cases

Every case is different, but we typically focus on several key areas.

• Challenging the traffic stop. Did the officer have a valid reason to stop you? If the stop was unlawful, everything that followed is tainted, and the charge should be dismissed.
• Questioning the DRE evaluation. We’ll examine exactly what the officer observed, how they interpreted it, and whether their conclusions meet scientific standards. We often hire our own expert to testify about the DRE process and its limitations.
• Disputing impairment. Just because you have a drug in your system doesn’t mean you were impaired. We’ll present evidence about your driving, your behavior, and expert testimony about the relationship between drug levels and actual impairment.
• Attacking the blood test. We’ll obtain the lab report, examine the methodology, and challenge any irregularities. We may request the actual lab records and challenge the certification status of the lab.
• Examining the prescription itself. We’ll work with a pharmacologist or toxicologist to understand when you took the medication, how it metabolizes, and whether therapeutic levels in your bloodstream are consistent with impairment at the time of driving.

What Happens Next: The DWI Process in Texas

After arrest, you’ll have an initial appearance or magistrate’s hearing. The officer will present probable cause for your arrest. This is not the time to defend yourself on the merits; it’s just to determine if probable cause exists (which is almost always found). Our attorneys will be there to protect your rights and begin building your defense.

You’ll be given bail information. In many DWI cases, especially first-time offenses, you can be released on your own recognizance or a small bond.

Within days, you should hire a DWI defense attorney. The prosecution will be building their case immediately. We need to do the same. We’ll request the police report, the officer’s notes, any video from the patrol car or station, the DRE evaluation notes, and the blood test results and methodology.

We’ll negotiate with the prosecutor. Many DWI cases, especially those involving only prescription drugs and no accident or injury, can be reduced or dismissed. We know the prosecutors in Dallas, Tarrant, Collin, Denton, and other DFW counties and understand their office’s approach to these cases.

If we can’t reach a favorable agreement, we’ll prepare for trial. This includes hiring experts, deposing the officer and any DRE evaluator, and preparing to challenge the state’s evidence at trial.

Protecting Your Driver’s License

A DWI arrest triggers an automatic driver’s license suspension under Texas Transportation Code. You have only 15 days from the date of your arrest to request a hearing with the Department of Public Safety (DPS). If you miss this deadline, your license will be automatically suspended.

We handle DPS license suspension hearings as part of our comprehensive DWI defense. Even if you’re ultimately acquitted of DWI, losing your license is a serious consequence. We’ll work to preserve your driving privileges while we defend the criminal case.

If You Have Questions—Contact Our Attorneys Today

A prescription drug DWI charge is serious, but it’s not the same as an alcohol DWI. The evidence is often weaker, the science is more questionable, and the defenses are often stronger. If you’ve been arrested in Dallas, Fort Worth, or any of the 16 counties we serve, contact the DWI Lawyer Dallas immediately.

Our attorneys have 35+ years of combined experience defending DWI cases. We know how to challenge prescription drug DWI charges and protect your rights. Call us today at 972-528-0116 for a free consultation, or contact us online. We’re available nights and weekends and serve clients throughout the Dallas-Fort Worth area.