Cannabis & Driving

What Missouri Drivers Need to Know Before Getting Behind the Wheel

Cannabis is legal for adults in Missouri, but driving under its influence is not. That distinction matters, and it’s one every cannabis consumer should understand before getting behind the wheel.

Being a responsible cannabis consumer means knowing where the line is. This guide explains how cannabis can affect driving ability, what Missouri law says about impaired driving, and what responsible use looks like when a vehicle is involved.

Cannabis & Its Effects on Driving Skills

Cannabis interacts with the body’s endocannabinoid system in ways that directly impact the skills needed to drive safely. Even at doses that feel manageable, it can impair:

• Reaction time – how quickly you respond to unexpected situations on the road
• Coordination – the ability to control the vehicle smoothly and accurately
• Depth perception – judging distances between your vehicle and others
• Divided attention – the ability to process multiple things at once
  
  

Of these, divided attention is one of the most significantly affected. Driving requires the brain to process road conditions, other vehicles, pedestrians, and signs all at the same time. Cannabis disrupts that process even when a consumer feels alert and in control.

Driving under the influence of cannabis also increases crash risk. Cannabis-impaired drivers tend to drive more slowly and cautiously than alcohol-impaired drivers, but that behavioral difference does not mean the impairment is less dangerous. It simply means it may look different.

Can You Drive After Consuming Cannabis?

No, if you have consumed cannabis, do not drive. There is no reliable way to self-assess whether you are impaired enough to be a danger on the road. Feeling fine is not the same as being safe to drive.

Cannabis affects each person differently based on:

• Tolerance and experience level
• The product consumed and its potency
• The dose
• Individual body chemistry
  
  

This applies to all product types, including edibles, which have a delayed onset and can produce stronger effects later than expected.

So, How Long After Consuming Cannabis Is It Safe to Drive?

There is no universally agreed-upon waiting period that guarantees safety.

Unlike alcohol, THC does not correlate reliably with impairment levels. The duration of impairment varies depending on the product, the dose, and the individual. Inhaled cannabis tends to produce shorter-lasting effects than edibles, which can cause impairment for 4 to 8 hours or longer.

If you’re unsure whether you’re still experiencing the effects of cannabis, avoid driving and arrange an alternative way to get where you’re going. 

Common Misconceptions About Cannabis & Driving

Some of the most dangerous decisions around cannabis and driving come from beliefs that feel reasonable but do not hold up. Here are the most common ones worth addressing directly.

“I drive better when I’m high.”

Research does not support this. Cannabis impairs the divided attention and reaction time required for safe driving. Feeling like you drive better does not necessarily reflect your actual driving ability.

“I only had a little, so I’m fine.”

Low doses can still impair driving, particularly for newer consumers or those with lower tolerance. There is no dose threshold below which driving is guaranteed to be safe.

“I’ll just drive slowly and carefully.”

Driving slowly does not eliminate impairment. Reaction time, depth perception, and divided attention are still affected regardless of speed.

“Edibles are fine because they take a while to kick in.”

Edibles are particularly risky for driving. A consumer who feels nothing after 45 minutes may experience significant impairment an hour later, potentially while behind the wheel.

If any of these sound familiar, it is worth reconsidering. None of them hold up when measured against what cannabis actually does to driving ability.

Driving High Comes With Serious Consequences in Missouri

The risks of driving after consuming cannabis go beyond getting caught. Impaired driving puts you, your passengers, and everyone else on the road in danger.

Missouri takes this seriously. The Missouri DWI statute RSMo 577.010, makes no distinction between alcohol or drug intoxication. There is no minimum THC level required for a charge

Missouri uses Drug Recognition Experts, trained officers who evaluate drivers for drug impairment through a standardized 12-step evaluation process.

A cannabis DWI carries the same legal consequences as an alcohol DWI, including:

• Fines
• License suspension
• Potential jail time depending on circumstances and prior record
  
  

A valid Missouri medical cannabis card does not provide any protection against a DWI charge. Medical patients are subject to the same impaired driving laws as all other drivers.

5 Tips for Responsible Use of Cannabis When Driving Is Involved

Taking a few simple precautions before you consume can help reduce unnecessary risks and support safer decision-making.

1. Plan ahead if you intend to consume cannabis, arrange transportation before you do.
2. Use a rideshare, designate a sober driver, or stay put until it is safe to travel.
3. Do not rely on self-assessment; cannabis impairment can make it harder to accurately judge whether you’re fit to drive.
4. Be especially cautious with edibles; their delayed onset can make it easier to underestimate how impaired you may become.
5. Never drive to a dispensary after consuming cannabis. Plan your visit before you consume.
   
   

Responsible cannabis use doesn’t end with choosing the right product. It also means making thoughtful decisions about when and how you travel. By planning ahead and avoiding driving while impaired, you can help protect yourself, your passengers, and everyone else on the road.

Cannabis & Driving: Key Takeaways

Cannabis can affect important driving skills such as reaction time, coordination, depth perception, and divided attention. Since impairment varies from person to person, there is no reliable self-test or universally accepted waiting period that can determine when it’s safe to drive.

Driving under the influence of cannabis is illegal in Missouri and carries the same legal consequences as driving under the influence of alcohol. It’s also important to remember that having a Missouri medical marijuana card does not exempt drivers from impaired driving laws.

The safest approach is to plan ahead before consuming cannabis. If driving may be involved, arrange alternative transportation and avoid getting behind the wheel until you are no longer impaired.