Alcohol, cannabis, medicine and fatigue

Key points

1. Alcohol is the most common impairing substance in impaired driving crashes.

   Source: PDF page 24

   “Alcohol is the most common impairing substance involved in impaired driving crashes.”
   Washington Driver Guide (plain-text version), PDF page 24

2. Cannabis is legal for those 21 and over.

   Source: PDF page 25

   “is legal for those 21 years or over, but driving after consuming any cannabis is illegal for all ages.”
   Washington Driver Guide (plain-text version), PDF page 25

3. There is no safe amount of cannabis for driving.

   Source: PDF page 25

   “There is no safe amount of cannabis for driving.”
   Washington Driver Guide (plain-text version), PDF page 25

4. Impaired driving is criminal whether the drug is prescribed, over the counter, retail or illegal.

   Source: PDF page 25

   “Impaired driving is a criminal behavior. It doesn’t matter if the drug is prescribed, obtained overthe-counter, bought in a retail setting, or considered an illicit substance.”
   Washington Driver Guide (plain-text version), PDF page 25

5. Polydrug use, mixing drugs, is the most common impairment involved in fatal crashes.

   Source: PDF page 26

   “Polydrug use is the most common impairment involved in fatal crashes.”
   Washington Driver Guide (plain-text version), PDF page 26

6. Open alcohol and cannabis products may be carried only in a trunk or truck bed.

   Source: PDF page 11

   “Open alcohol and cannabis products can only be transported in a trunk or truck bed.”
   Washington Driver Guide (plain-text version), PDF page 11

7. If you feel tired while driving alone, pull off and take a 20 minute nap.

   Source: PDF page 26

   “If you’re traveling alone and start to feel tired, pull off the road and take a 20-minute nap.”
   Washington Driver Guide (plain-text version), PDF page 26

8. Most people need 7 to 9 hours of sleep to stay alert.

   Source: PDF page 26

   “most people need 7 to 9 hours to stay alert.”
   Washington Driver Guide (plain-text version), PDF page 26

9. On long trips, plan to stop about every 100 miles or 2 hours.

   Source: PDF page 26

   “Plan to stop about every 100 miles or 2 hours during long trips.”
   Washington Driver Guide (plain-text version), PDF page 26

10. Like alcohol and drugs, fatigue impairs your vision and judgment.

    Source: PDF page 26

    “Like alcohol and drugs, fatigue impairs your vision and judgment.”
    Washington Driver Guide (plain-text version), PDF page 26

Numbers to know

3 questions from the Washington practice test

1. 1. In Washington, how old must a person be to legally use recreational cannabis?

   1. 21 years or over
   2. 18 years or over
   3. 20 years or over
   4. Any age with a licensed driver present
   Show answer

   21 years or over. The Washington guide says recreational use of marijuana, THC, and other cannabis products is legal for those 21 years or over. Eighteen and twenty fall short of that age, and having a licensed driver nearby does not change who may use cannabis. Legal use is a separate matter from driving. A driver 21 or older can still be charged with DUI at 5.00 nanograms of THC per milliliter of blood or more, or when affected by it, and drivers under 21 face a zero limit. Arrange another ride instead of estimating when the effects have faded.

2. 2. What does the Washington guide mean by polydrug use?

   1. Taking a drug more than once a day
   2. Using only prescription drugs
   3. Mixing or taking more than one type of drug, which can produce effects greater than any drug on its own
   4. Drinking on an empty stomach
   Show answer

   Mixing or taking more than one type of drug, which can produce effects greater than any drug on its own. Polydrug use is the mixing or taking of more than one type of drug. Mixing alcohol, cannabis or other drugs can produce effects greater than any drug on its own, and the category includes alcohol, cannabis, illegal drugs, prescription drugs, over the counter medicines and other substances such as inhalants. Read medicine warnings or ask a pharmacist before combining anything with alcohol.

3. 3. Where may open alcohol or cannabis products be transported in a Washington vehicle?

   1. In the glove box
   2. Only in a trunk or truck bed
   3. Under a seat
   4. In the center console
   Show answer

   Only in a trunk or truck bed. Open alcohol and cannabis products can only be transported in a trunk or truck bed. Containers cannot be kept in storage compartments accessible to the driver, and alcohol or cannabis in unlabeled or mislabeled containers is also prohibited. The rule applies to passengers as well. Keeping open products out of reach removes any question of consumption while driving and protects passengers from a citation.

Source: the Washington Driver Guide (plain-text version), Chapter 3: Drivers. This lesson is a plain English summary, not the law itself; where it differs, the manual and the statute govern. Last checked 2026-09-27.