DUI Lawyer | Joel Brand, Esq.

How Prescription Drugs Affect Your DUI Defense

In California, driving under the influence (DUI) laws are stringent and extend beyond alcohol consumption to include the influence of drugs, including prescription medications. Many drivers are unaware that certain prescription drugs can significantly affect their performance on field sobriety tests (FSTs), breathalyzer readings, blood test results, and ultimately, their blood alcohol concentration (BAC). Understanding how these drugs interact with your body and the legal implications is crucial for anyone who drives while on prescription medication.

Understanding DUI Laws in California

Under California Vehicle Code Section 23152, it is unlawful to drive a vehicle while under the influence of alcohol, drugs, or a combination of both. This includes prescription drugs that impair your ability to drive safely. The law does not differentiate between illegal drugs, over-the-counter medications, and prescription drugs; if a substance impairs your ability to operate a vehicle, you can be charged with DUI.

Prescription Drugs and Field Sobriety Tests (FSTs)

Field sobriety tests are standardized tests used by law enforcement officers to assess a driver’s level of impairment. These tests include the Horizontal Gaze Nystagmus (HGN), the Walk-and-Turn, and the One-Leg Stand, among others. While these tests are primarily designed to detect alcohol impairment, certain prescription drugs can also affect your performance on these tests, leading to a false positive indication of impairment.

1. Benzodiazepines (e.g., Xanax, Valium)

  • Impact on FSTs: Benzodiazepines are commonly prescribed for anxiety and insomnia. They can cause drowsiness, dizziness, and poor coordination, all of which can significantly impair your performance on FSTs. For example, the Walk-and-Turn and One-Leg Stand require good balance and coordination, both of which can be adversely affected by benzodiazepines.
  • Legal Implications: If an officer suspects impairment based on your performance on FSTs, you could be arrested and charged with DUI, even if your impairment is due to a legally prescribed medication.

2. Opioids (e.g., Oxycodone, Hydrocodone)

  • Impact on FSTs: Opioids are potent pain relievers but come with side effects like drowsiness, confusion, and impaired judgment. These effects can make it difficult to follow instructions during FSTs, leading to poor performance. The HGN test, which tracks eye movements, can also be influenced by opioid use, as these drugs can cause unusual eye movements.
  • Legal Implications: Failing an FST due to opioid-induced impairment can result in a DUI charge, even if the medication was legally prescribed for pain management.

3. Antihistamines (e.g., Diphenhydramine, Loratadine)

  • Impact on FSTs: Antihistamines, particularly those that cause drowsiness, can impair your ability to perform FSTs. Drugs like Diphenhydramine (Benadryl) can cause sedation and slowed reaction times, which can negatively affect your balance and coordination during these tests.
  • Legal Implications: Despite being over-the-counter medications, antihistamines can still result in DUI charges if they impair your ability to drive.

Prescription Drugs and Breathalyzer Readings

Breathalyzer tests are commonly used by law enforcement to measure a driver’s BAC. However, some prescription medications can interfere with the accuracy of these tests, leading to false positives or artificially inflated BAC readings.

1. Mouthwash and Breath Sprays Containing Alcohol

  • Impact on Breathalyzer: While not prescription drugs, mouthwash, and breath sprays often contain alcohol, which can lead to false-positive readings on a breathalyzer test. If you’ve recently used a mouthwash that contains alcohol, it could register as alcohol consumption, even if you haven’t been drinking.
  • Legal Implications: A false positive on a breathalyzer can lead to an unwarranted DUI arrest and charges, which can be contested with the help of a knowledgeable DUI attorney.

2. Inhalers (e.g., Albuterol)

  • Impact on Breathalyzer: Some studies suggest that inhalers used for asthma or other respiratory conditions can affect breathalyzer readings. The alcohol content in the propellant used in certain inhalers might lead to a false positive or an artificially high BAC reading.
  • Legal Implications: If you use an inhaler and are subjected to a breathalyzer test, it’s essential to inform the officer and seek legal counsel to address any potential inaccuracies in the BAC reading.

Prescription Drugs and Blood Test Results

Blood tests are often considered more accurate than breathalyzers for determining BAC. However, prescription medications can also influence the results of these tests, especially when combined with alcohol or other substances.

1. Antidepressants (e.g., SSRIs like Prozac or Zoloft)

  • Impact on Blood Tests: Antidepressants can interact with alcohol in unpredictable ways, sometimes leading to higher BAC levels than expected. Certain antidepressants can also remain in the bloodstream for extended periods, potentially complicating the interpretation of blood test results.
  • Legal Implications: If you’re taking antidepressants, your BAC may not accurately reflect your level of impairment. A DUI attorney can challenge the validity of the blood test results, especially if the test was administered without considering the interaction between the medication and alcohol.

2. Anti-Seizure Medications (e.g., Dilantin)

  • Impact on Blood Tests: Anti-seizure medications can alter the way your body metabolizes alcohol, potentially leading to higher BAC levels. These medications can also cause side effects like dizziness and confusion, which might be misinterpreted as alcohol-induced impairment.
  • Legal Implications: A DUI charge based on blood test results influenced by anti-seizure medication can be contested, especially if the test results don’t accurately reflect your level of impairment.

Prescription Drugs and BAC Levels

BAC is a measure of the amount of alcohol in your bloodstream, typically expressed as a percentage. While prescription drugs don’t contain alcohol, they can interact with alcohol in ways that affect your BAC levels.

1. Antibiotics (e.g., Metronidazole)

  • Impact on BAC: Certain antibiotics can interact with alcohol to produce a disulfiram-like reaction, which includes nausea, vomiting, and a rapid heartbeat. This reaction can make even small amounts of alcohol seem more intoxicating, potentially leading to a higher perceived BAC.
  • Legal Implications: If you’re taking an antibiotic that interacts with alcohol, your BAC might be higher than expected, leading to a DUI charge. A knowledgeable DUI attorney can argue that the interaction between the medication and alcohol affected the BAC reading.

2. Anti-Anxiety Medications (e.g., Benzodiazepines)

  • Impact on BAC: Benzodiazepines can enhance the effects of alcohol, leading to greater impairment at lower BAC levels. This interaction might result in a BAC that doesn’t accurately reflect your level of impairment but still leads to a DUI charge.
  • Legal Implications: A DUI defense attorney can argue that the interaction between the medication and alcohol created a misleading BAC reading, potentially leading to a reduced charge or dismissal.

Defending Against DUI Charges Involving Prescription Drugs

If you’re charged with a DUI involving prescription drugs, several defense strategies may be available. These can include:

  1. Challenging the Validity of the FSTs: If your performance on the FSTs was impaired due to a prescription drug, your attorney can argue that the tests were not a valid indicator of alcohol-related impairment.
  2. Questioning the Accuracy of Breathalyzer or Blood Test Results: If your prescription medication affected the results of these tests, your attorney can challenge their validity in court.
  3. Arguing a Lack of Intent: Since prescription drugs are legal and often necessary for your health, your attorney can argue that you had no intent to drive under the influence, potentially leading to reduced charges or an alternative sentencing option.

Conclusion

Driving under the influence of prescription drugs can lead to severe legal consequences, including DUI charges, even if the medication was legally prescribed. Understanding how these drugs can affect your performance on field sobriety tests, breathalyzer readings, blood test results, and BAC is crucial for anyone taking prescription medication. If you’re facing a DUI charge involving prescription drugs, it’s essential to consult with an experienced DUI attorney who can help you navigate the complexities of your case and protect your rights.