How Long After Consuming Cannabis Can I Drive Safely?

How Long After Consuming Cannabis Can I Drive Safely?

The impact of cannabis on driving abilities can differ depending on factors such as the amount used, the method of intake (smoking vs. eating), and the frequency of use.

For example, if you smoke or vaporize cannabis and perform simple tasks that require mental skills like reaction time, sustained attention, and working memory, the usual impairment duration is about 4 hours. But if you consume high doses of THC orally, the impairment could last up to 10 hours1.

Understanding About Cannabis

Cannabis, also known as weed, pot, or marijuana, is a term that encompasses three plants with psychoactive characteristics: Cannabis sativa, Cannabis indica, and Cannabis ruderalis. The dried blossoms of these plants are frequently utilized for their soothing and calming effects.

Over 120 components are found in the cannabis plant known as cannabinoids. The most recognized cannabinoids are cannabidiol (CBD) and tetrahydrocannabinol (THC). CBD is a psychoactive cannabinoid that is non-intoxicating and non-euphoric, so it doesn’t produce a “high”. It’s commonly used to alleviate inflammation and pain. 2

The Effects of Cannabis on Driving

Cannabis is known to contain THC (Delta-9-Tetrahydrocannabinol), which has been proven to cause acute impairment in driving and cognitive abilities. Ingesting an excessive amount of THC can result in intense anxiety attacks, potentially necessitating a visit to the emergency room. It could also activate other health issues, such as cardiac arrhythmias and syncope.

Duration of Impairment

According to a study from Harvard Health, the period of impairment after using cannabis can significantly differ based on various factors. It’s recommended not to operate a vehicle for a minimum of four hours post-smoking cannabis, even if you feel capable of driving safely before that time. If you’ve consumed an edible, it’s advised to wait between 8 to 12 hours prior to driving.

Another study indicates that if you smoke a single joint of marijuana, which typically contains 60 to 140mg of THC, you might need to abstain from driving for at least 24 hours.

What Are Some Alternatives To Driving After Consuming Cannabis?

If you’ve used cannabis and need to travel, there are several safe alternatives to driving yourself:

  • Public Transportation: Options like buses, trams, trains, and subways are often safe and reliable.

  • Rideshare Apps: Services such as Uber and Lyft offer a convenient solution.

  • Taxi Services: Traditional taxis are readily available in most urban areas.

  • Designated Driver: If you’re in a group, select a member who won’t be using cannabis to drive.

  • Walking or Biking: If your destination is close and it’s safe, consider walking or cycling.

Always remember that your safety is paramount. It’s crucial to plan your travel in advance if you intend to use cannabis.

Penalties For Driving Under The Influence Of Cannabis

The consequences of driving while under the influence of cannabis can be quite severe and are often comparable to those associated with driving under the influence of alcohol. These can include:

  • License suspension: This could last anywhere from 90 days to a year.

  • Monetary fines: These could range from around $500 to $2,000.3

  • Incarceration: This could last up to a year, although most first-time offenders typically do not serve substantial jail time.

  • Prison sentence: This is applicable for more serious offenses and could last a year or more.4

It’s important to remember that these are general penalties, and the exact consequences can vary based on the jurisdiction and the specifics of the offense. Driving under the influence of any substance, including cannabis, is illegal and dangerous. It’s always best to refrain from driving if you’ve consumed cannabis or any other substance that could potentially impair your ability to drive safely.

gavel with minimal hemp leaf on the background

The permissible levels of THC (delta-9-tetrahydrocannabinol) in the blood while driving can differ based on the jurisdiction. Here are a few instances:

  • In Michigan, there’s a proposed bill (HB 4727) that seeks to establish a legal limit of 5 nanograms of THC per milliliter of blood5.

  • In certain jurisdictions, drivers with over 5 nanograms of THC in their blood could be deemed guilty of impaired driving. If drivers have both alcohol and THC in their system, they could be considered impaired if they have more than 50 milligrams of alcohol (per 100 milliliters of blood) and over 2.5 nanograms of THC in their blood.6

  • Six states in the U.S., specifically Illinois, Montana, Nevada, Ohio, Pennsylvania, and Washington, have laws that set a nanogram limit for THC that ranges between one to five nanograms.

 Medical Uses Of Cannabis

Cannabis, also referred to as medical marijuana, is used to mitigate symptoms associated with certain health conditions. Here are some of the therapeutic uses of cannabis:

  • Pain and Inflammation Management: Cannabis can aid in managing pain and inflammation.

  • Control of Nausea, Vomiting, Appetite Loss, or Weight Loss: It can be employed to regulate nausea, vomiting, loss of appetite, or weight loss.

  • Nerve Damage Management: Cannabis can assist in managing sensations of tingling or numbness resulting from nerve damage.

  • Treatment of Mood and Sleep Disorders: It can be used to address mood and sleep disorders.

  • Control of Muscle Spasms, Tremors, Seizures, or Tics: Cannabis can aid in controlling muscle spasms, tremors (shaking), seizures, or tics.

  • Management of Glaucoma: It can be employed to manage fluid pressure in the eye resulting from glaucoma.

  • Chronic Pain Management in Adults: There is significant evidence supporting the use of cannabis in treating chronic pain in adults.

  • Management of Chemotherapy-induced Nausea in Cancer Patients: Cannabis can be employed to manage nausea induced by chemotherapy in cancer patients.

  • Management of Spasticity Symptoms in Multiple Sclerosis Patients: It can be used to manage spasticity symptoms in patients with multiple sclerosis.

cannabis plant

Side Effects Of Driving Under The Influence Of Cannabis

Operating a vehicle while under the influence of cannabis can lead to several side effects, as it can delay important skills needed for safe driving. Here are some potential impacts:

  • Delayed Reaction Time and Decision Making: Cannabis can decelerate your reaction time and decision-making ability, which are vital for quickly responding to unforeseen situations on the road.

  • Impaired Coordination: It can impact your body’s movements, balance, and coordination, which are crucial for operating a vehicle.

  • Altered Perception: Cannabis can alter your perception, making it challenging to gauge distances and react accordingly.

  • Memory Loss and Problem-Solving Difficulty: Cannabis can result in memory loss and problem-solving difficulty, which could be hazardous when driving.

  • Impaired Multitasking Ability: Driving necessitates the effective ability to multitask. Cannabis use can hinder this ability.

Safety Measures

For safety reasons, it’s advised not to operate a vehicle for at least 4 hours after smoking cannabis. If you’ve ingested a cannabis-infused edible, it’s recommended to wait eight to 12 hours before getting behind the wheel. However, these are just general guidelines, and individual reactions to cannabis can differ. So, if you feel impaired or uncertain, it’s always safer to refrain from driving.


 Don’t drive high. Your safety and the safety of others on the road depend on it.

drive safe sign on the road


Even though the use of cannabis is legal in many areas, it’s vital to consume it in a responsible manner. If you intend to drive, ensure you allow a sufficient amount of time to pass after consumption. Always prioritize safety.


What is the late stage of cannabis ripening?
The final stage of cannabis ripening begins around the seventh week. During this phase, the cannabis buds reach their maximum weight and size.
What are the effects of cannabis on driving?
Cannabis can impair critical driving skills such as reaction time, decision making, coordination, perception, memory, problem-solving, and multitasking. This can lead to slowed reactions, impaired coordination, distorted perception, memory loss, difficulty in problem-solving, and impaired multitasking ability
What are the risks of cannabis use in youth?
Cannabis use in youth can lead to temporary psychosis, which includes hallucinations, paranoia, and not being able to distinguish what’s real.
What are the effects of regular heavy use of cannabis in adolescents?
Adolescents are more sensitive than adults to the adverse effects of regular heavy use of cannabis. These effects include cognitive impairment, dependence, poor psychosocial development, impaired school and work performance, drug-related psychiatric illness, and generally poorer treatment outcomes.


  1. “Study Calculates Duration of Driving Impairment after Smoking Cannabis.” New Atlas, 13 Apr. 2021, Accessed 8 Oct. 2023. ↩︎
  2. Holland, Kimberly. “A Quick Take on Cannabis and Its Effects.” Healthline, Healthline Media, 29 Oct. 2018, Accessed 8 Oct. 2023. ↩︎
  3. McCurley, John. “Can I Get a DUI for Driving High on Marijuana?”, Nolo, 18 Dec. 2017, Accessed 8 Oct. 2023. ↩︎
  4. “Marijuana DUI: How Marijuana Use Can Be Considered a DUI.”, 2 Oct. 2014, Accessed 8 Oct. 2023. ↩︎
  5. “Setting Legal Limits for THC in the Bloodstream: Are You Too High to Drive?” Grewal Law PLLC, Accessed 8 Oct. 2023. ↩︎
  6. Zimonjic, Peter, and Catherine Cullen. “Government Releases Legal Limits for Drugged Driving but Can’t Say How Much Pot Is Too Much.” CBC, 14 Oct. 2017, Accessed 8 Oct. 2023. ↩︎
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