CDOT’s Safety Guide for 420 Celebrations

Stay Safe and Avoid a DUI — Never Drive Impaired

The lawn of the 420 Mile High Festival in Denver Colorado

Whether you’re attending 420 on the Rocks, The Mile High 420 Festival or just hanging out with friends, make sure your April 20 plans include a sober ride home. While cannabis consumption is legal in Colorado, driving high is not — any amount of impairment puts you at risk for a DUI. Although the number of people who report driving after using cannabis is down, in 2022 there were 101 traffic deaths in Colorado that involved cannabis above the legal limit. As heavy cannabis consumption coincides with cannabis-inspired events, CDOT is offering important planning and safety tips to consumers.

Drive High, Get a DUI

You can get a DUI for driving under the influence of cannabis, and the primary mode of detection is roadside impairment testing.

The law states that if you are impaired to the slightest degree, you can be arrested — no matter what the substance. That is why Colorado law enforcement officers are increasingly trained to identify drivers impaired by alcohol, marijuana and other drugs. Colorado currently has 136 law enforcement certified as Drug Recognition Experts (DREs).In addition, many Colorado law enforcement officers have received special training in Advanced Roadside Impaired Driving Enforcement (ARIDE). Law enforcement officers base arrests on observed impairment.

Mixing Amplifies Impairment

Mixing cannabis and alcohol, or any other impairing substance, enhances the impairing effects of both and can be especially dangerous on the road.

Research shows that users are more likely to drive — or take other risks — after using both substances than after consuming marijuana alone. You can get a DUI even if you’re under the legal limit of both alcohol and cannabis. A report by the Colorado Division of Criminal Justice (DCJ) published in July 2023 analyzed 2020 data from more than 21,000 impaired driving cases filed in Colorado and found that 75% of people with Delta-9 THC detected in their system also had some other substance present. Alcohol and cannabis were the most common co-occurring substances. In 2022, 29% of the fatal crashes that tested for more than one drug tested positive for multiple impairing substances.

How Long to Wait

Everyone is different, and experience levels and consumption methods will impact your impairment. Here are some general guidelines:

  • Wait at least six hours after smoking cannabis containing less than 35 mg of THC before driving or performing other safety-sensitive activities. If you’ve smoked more than 35 mg, you need to wait longer.
  • Wait at least eight hours after eating or drinking cannabis containing less than 18 mg of THC before driving. If you’ve eaten more than 18 mg, wait longer.
  • If you’re mixing cannabis with alcohol, you need to wait even longer.

Given these long wait times, it is always best to plan ahead for a sober ride home.

Know What You’re Consuming

Delta-9 Tetrahydrocannabinol (Delta-9 THC) is the most commonly found psychoactive and impairing substance in cannabis products in Colorado. However, products sold at dispensaries, along with some sold on the general market, may also contain other cannabinoids like CBD, CBN, CBG or others. Some are psychoactive, some may not be, but don’t assume that if it’s not THC, it won’t impair your ability to drive.

CDOT’s Meet The Effects awareness campaign will be active in broadcast, digital, print and out-of-home media from April to June. The campaign educates consumers about marijuana-impaired driving by personifying how cannabis negatively impacts driving performance.