The Hidden Dangers of Driving on Medication
Driving while impaired is illegal in all 50 states, and this doesn't just apply to alcohol or illicit substances [1.5.5]. Many common prescription and over-the-counter (OTC) medications can significantly affect your coordination, judgment, and reaction times, making it unsafe to operate a vehicle [1.5.1]. The side effects can be subtle, and you might not even feel impaired, yet your ability to react to road hazards could be dangerously compromised [1.6.2, 1.9.2]. It is a crime to drive under the influence of any substance that impairs your ability, even if it's a legally prescribed medication [1.5.2].
Prescription Medications That Impair Driving
Always read warning labels and consult your doctor or pharmacist about how a new medication might affect you. The warning against "operating heavy machinery" includes driving a car [1.6.3].
Opioid Painkillers
Opioids such as oxycodone, hydrocodone, and morphine are powerful analgesics that can cause drowsiness, dizziness, and cognitive impairment [1.2.4, 1.8.1]. Studies show that drivers who test positive for opioids can be up to eight times more likely to be involved in a traffic crash [1.8.2]. The risk is particularly high when first starting therapy or if the dose is changed [1.8.3].
Benzodiazepines (Anti-Anxiety Medications)
Drugs like Xanax (alprazolam), Valium (diazepam), and Klonopin (clonazepam) are prescribed for anxiety and other conditions. They act as central nervous system depressants, which can slow reaction time, impair coordination, and cause drowsiness [1.2.3, 1.7.4]. Even long-term users can experience significant impairment in driving performance [1.7.2].
Sleep Aids (Hypnotics)
Medications like Ambien (zolpidem) can cause significant impairment, even the morning after they are taken [1.10.2]. The FDA has issued warnings and recommended lower doses, especially for women, due to the risk of next-morning impairment [1.10.1]. Many people affected by impairment from sleep aids do not recognize their own hindered state [1.10.4].
Antidepressants
Certain antidepressants can cause drowsiness, blurred vision, and affect cognitive skills essential for driving [1.2.1, 1.2.5]. While newer antidepressants may have fewer of these side effects, it's crucial to know how any specific medication affects you before getting behind the wheel.
Other Prescription Drugs of Concern
- Muscle Relaxants: These can cause significant drowsiness and dizziness, slowing down brain function and reaction times [1.11.1, 1.11.2].
- Antiseizure Medications: Can cause sleepiness, dizziness, and blurred vision [1.2.1].
- Antipsychotic Medicines: These can also impair motor skills and cognitive function [1.2.4].
Surprisingly Risky Over-the-Counter (OTC) Drugs
Many people underestimate the potential for OTC medications to cause driving impairment.
Antihistamines
First-generation antihistamines, like diphenhydramine (found in Benadryl) and doxylamine (in Nyquil), are notorious for causing drowsiness [1.6.1, 1.9.3]. The impairment from a single dose can be equivalent to being over the legal blood alcohol limit [1.6.1]. Even if you don't feel drowsy, these medications can slow reaction time and make it hard to focus [1.9.4]. Newer, second-generation antihistamines like loratadine (Claritin) and fexofenadine (Allegra) are less likely to cause drowsiness, but cetirizine (Zyrtec) can still cause it in some people [1.9.3].
Cold and Flu Remedies
Many multi-symptom cold and flu products, especially those labeled for "nighttime" use, contain antihistamines or other ingredients that cause drowsiness [1.2.4]. Always check the "Drug Facts" label for active ingredients and warnings [1.6.5].
Other OTC Products
- Motion Sickness Pills: Drugs like Dramamine can cause significant drowsiness [1.3.3].
- Anti-diarrheal Medications: Products containing loperamide (Imodium) can cause drowsiness and dizziness in some individuals [1.3.3, 1.6.1].
- Stimulants: While meant to keep you awake, diet pills or "stay awake" medicines containing caffeine or pseudoephedrine can cause anxiety, dizziness, or excitability, which can also negatively impact driving [1.3.2].
Comparison of Impairing Drug Classes
| Drug Class | Common Examples | Primary Impairing Effects on Driving |
|---|---|---|
| Opioids | OxyContin, Vicodin, Codeine | Drowsiness, dizziness, slowed reaction time, euphoria [1.8.1, 1.8.2] |
| Benzodiazepines | Xanax, Valium, Klonopin | Drowsiness, confusion, slowed reaction time, poor coordination [1.2.3] |
| Sleep Aids | Ambien, Lunesta, Melatonin | Significant next-morning drowsiness, dizziness, impaired judgment [1.10.1, 1.10.2] |
| 1st-Gen Antihistamines | Benadryl, Nyquil (Doxylamine) | Marked drowsiness, inability to focus, slowed movement [1.6.1, 1.9.3] |
| Muscle Relaxants | Flexeril, Soma | Drowsiness, fatigue, dizziness, confusion [1.11.1, 1.11.2] |
Conclusion: Prioritize Safety Above All
It is illegal and dangerous to drive while impaired by any substance, including legally obtained medications [1.5.5]. The consequences of a drugged driving DUI can be just as severe as an alcohol-related one, including fines, license suspension, and even jail time [1.5.3]. The safest course of action is to always understand your medication's side effects. When starting a new prescription, avoid driving until you know how it affects you [1.6.4]. If a medication causes impairment, plan for alternative transportation, such as a rideshare service or asking a friend for a ride [1.5.3]. Always talk to your doctor or pharmacist about your concerns.
For more information from an authoritative source, visit the NHTSA's page on Drug-Impaired Driving.
