How alcohol and drugs affect driving

Key points

1. Alcohol and other impairing drugs are involved in about 40% of all fatal crashes.

   Source: Handbook p. 22

   “Alcohol and other impairing drugs are involved in approximately 40% of all fatal crashes.”
   Kansas Driving Handbook, Handbook p. 22

2. Under 21 it is illegal to buy, possess or drink alcohol.

   Source: Handbook p. 22

   “If you are under the age of twenty-one (21), it is illegal to purchase, possess or drink alcoholic beverages.”
   Kansas Driving Handbook, Handbook p. 22

3. Vision is affected at .02 BAC for all drivers.

   Source: Handbook p. 23

   “Vision is impacted at .02 BAC for all drivers.”
   Kansas Driving Handbook, Handbook p. 23

4. Alcohol and other impairing drugs reduce your ability to tell colors apart, which is dangerous on the road.

   Source: Handbook p. 23

   “Alcohol and other impairing drugs reduce your ability to distinguish colors, which can be very dangerous.”
   Kansas Driving Handbook, Handbook p. 23

5. Coffee, fresh air, cold showers or eating will not sober you up; only time works.

   Source: Handbook p. 23

   “Coffee, fresh air, cold showers or eating will not help to remove the alcohol or other drug combination from the circulatory system.”
   Kansas Driving Handbook, Handbook p. 23

6. The body needs about 1 hour to clear one normal drink, so after 4 drinks wait 4 hours or more before driving.

   Source: Handbook p. 23

   “It takes about an hour for the body to get rid of one normal drink from the circulatory system. Therefore, if someone has had four normal drinks, they should wait four hours or more before they drive.”
   Kansas Driving Handbook, Handbook p. 23

7. Impairment starts with the first drink; even one drink can affect your ability to drive.

   Source: Handbook p. 23

   “Impairment starts with the first drink. Even one drink of alcohol can affect a person's ability to operate a motor vehicle.”
   Kansas Driving Handbook, Handbook p. 23

8. Over the counter medicines for headaches, colds, allergies or nerves can make you drowsy and affect your driving.

   Source: Handbook p. 24

   “Over-the-counter drugs taken for headaches, colds, hay fever or other allergies or those to calm nerves can make you drowsy and affect your driving.”
   Kansas Driving Handbook, Handbook p. 24

9. Even below .08 you are still impaired, and you can still be convicted of driving impaired.

   Source: Handbook p. 23

   “Even under .08 you are still impaired. Under the law you can still be convicted for driving impaired.”
   Kansas Driving Handbook, Handbook p. 23

10. Never drink alcohol while taking other drugs, which can multiply its effects.

    Source: Handbook p. 24

    “Never drink alcohol while you are taking other drugs. These drugs could multiply the effects of alcohol or have additional effects of their own.”
    Kansas Driving Handbook, Handbook p. 24

Numbers to know

3 questions from the Kansas practice test

1. 1. At what BAC does the Kansas handbook say vision is impacted for all drivers?

   1. .08%
   2. .05%
   3. .10%
   4. .02%
   Show answer

   .02%. The handbook identifies .02 BAC as the point at which vision is impacted for all drivers. That is an early warning level, not the .08 figure used for the general alcohol violation described later. The .10% choice is higher than both handbook figures and therefore misses the onset of the visual effect. The .05% option also has no support in this passage. A useful study cue is to connect .02 with vision, then separately remember .08 as the standard alcohol limit. Even before a driver reaches the higher legal threshold, reduced focus, distance judgment, or lane control can make driving unsafe.

2. 2. What does the Kansas handbook say is illegal for anyone under 21 regarding alcohol?

   1. Only buying alcohol for others
   2. Only driving after drinking
   3. Purchasing, possessing, or drinking alcoholic beverages
   4. Nothing if a parent consents
   Show answer

   Purchasing, possessing, or drinking alcoholic beverages. If you are under 21 in Kansas it is illegal to purchase, possess or drink alcoholic beverages at all, not only to drive after drinking. Alcohol and other impairing drugs affect a person's ability to perceive their surroundings, react to emergencies and operate a vehicle, and the effects are greater for new drivers still learning complex skills. Parental consent does not create an exception under the rule the handbook states.

3. 3. Can a Kansas driver still be convicted of driving impaired with a BAC below .08?

   1. Yes, impairment can support a conviction below .08
   2. No, .08 is an absolute minimum
   3. Only if the driver is under 21
   4. Only when a blood test is unavailable
   Show answer

   Yes, impairment can support a conviction below .08. Kansas describes .08 or higher as a violation, but it also warns that a driver remains impaired below .08 and can still be convicted for driving impaired. The .08 threshold is therefore not a safe harbor. The choice “No, .08 is an absolute minimum” incorrectly turns that number into an absolute minimum. The under-21 choice confuses this rule with the separate lower BAC enforcement described for younger drivers. The testing choice adds a condition the handbook does not require. Remember the distinction: .08 is the standard alcohol violation figure, while impairment can exist and lead to a conviction below it.

Source: the Kansas Driving Handbook, Section 3: Be in Shape to Drive. 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.