Driving High: Why You Shouldn't Drive on Weed, and Why It's Hard to Test

Is Driving High Dangerous? Yes. Here's What the Data Says

Don't drive high. Cannabis slows your reaction time and messes with your coordination and your sense of distance, and driving under its influence is illegal in most places. What researchers still argue about is how to measure that impairment, because THC levels in your blood don't line up neatly with how impaired you actually are. That's a headache for police and researchers, not a loophole for you: if you're high, you're not the one driving.

With alcohol, blood alcohol content and impairment usually rise together. Breathalyzers are a quick, non-invasive way to tell whether a driver is drunk.

Testing for stoned drivers isn't that simple. Some US jurisdictions, including Colorado, have set limits for how much cannabis in your system counts as impaired driving, such as five nanograms of THC per milliliter of blood. But there's no straight-line relationship between THC concentration in the blood and how impaired someone is, and the tests require a blood or saliva sample.

On top of that, THC can stay detectable in the blood for weeks in regular users, so compared with alcohol, its presence says less about the driver's actual state. All of this makes it tough to figure out whether legalization makes the roads more dangerous. Some places have laws that make a set blood concentration of THC illegal, whether or not the driver seems impaired.

So while weed can affect motor skills, the available data, as discussed in a 2017 report from the US National Highway Traffic Safety Administration, suggests the odds of being in a crash right after using cannabis are significantly lower than the crash rates after drinking. Lower than alcohol is not the same as safe.

The usual explanation is that alcohol makes drivers more aggressive and reckless, while stoned drivers are more likely to drive too slowly, which is a hazard of its own.

So driving high is generally illegal, but researchers still can't pin down how big the problem is across the population, or whether police tactics can do much about it. Still, public safety means places with legal cannabis have to think the issue through and, sometimes, take action.

Before legalizing recreational cannabis in October 2018, Canada approved a device called the Dräger DrugTest 5000 as a roadside saliva tester for THC. But its accuracy has been questioned; it's known to produce both false positives and false negatives. And even when it gets the reading right, it doesn't claim to tell whether someone is fit to drive.

Eaze, a California cannabis delivery service, recently surveyed cannabis users about how they get around.

• 

It found that 64% of cannabis users say they drive within four hours of using, and 20% say they drive within an hour. Users couldn't agree on how much cannabis they consider "safe" before driving (no study backs any amount), and everyone was less likely to drive high with a kid in the car.

Among adults who use and drive, 77% believe it doesn't affect their driving and 16% believe it makes them better drivers, according to the survey. That's what people believe, not how they actually drive. Men and younger drivers are more likely to drive within eight hours of using.

The bottom line: don't drive under the influence of anything, cannabis included, and stay alert and focused behind the wheel. Researchers are still working out exactly how driving high compares with other impairments, but none of that research says it's safe. What's beyond debate: never drive drunk, and never drive high. If you've used, hand over the keys, call a ride or wait it out.

• 

What Are the Positive and Negative Effects of Weed?

Cannabis can have both positive and negative effects on a person's health and well-being. Some of the positive effects people report include:

• Pain relief: weed may reduce how much pain some people feel, which can help with chronic pain and other medical conditions.
• Less anxiety and stress: some people find cannabis helps bring their anxiety and stress levels down.
• Better sleep: some people find weed helps them sleep better and deal with insomnia.
• Appetite boost: cannabis can stimulate appetite (yes, the munchies), which can help people who struggle to eat or keep weight on because of an illness or medical treatment.

That said, there are also negative effects linked to cannabis use, such as:

• Short-term effects: weed can affect coordination, balance and your ability to judge time and distance, which raises the risk of accidents and injuries. It can also cause dizziness, nausea and other side effects.
• Long-term effects: frequent, long-term use may hurt memory, attention and the ability to learn and make decisions. It can also affect mental health and raise the risk of problems like depression, anxiety and psychosis.
• Health risks: cannabis can be hard on the respiratory system, especially when smoked. It may also affect heart health and raise the risk of problems like high blood pressure and stroke.

If you want to come down from a high and clear THC from your system, here are a few tips people follow:

1. Hydration: drinking enough water and fluids keeps you feeling better while the high wears off, though it won't flush THC out dramatically faster.
2. Exercise: physical activity revs up your metabolism and can help your body clear THC. Just keep in mind that working out while you're high can raise your risk of injury.
3. Fatty foods: THC is stored in body fat, and some people swear that eating fatty foods helps clear it faster, though there's little evidence behind it.
4. Rest: if you feel dizzy or anxious, rest somewhere quiet and comfortable. Sleep can also help your body work through the THC.

Keep in mind that THC can stay in your blood and urine for several days or even weeks, depending on how much you used, how often you use and your own metabolism.

As for how long a high lasts, the effects of an indica can stick around for several hours, depending on the strain, how much you took and your tolerance. The effects usually kick in within the first 30 minutes and can last 2 to 6 hours, and edibles can last longer. Plan your ride home before you light up.

Keep reading our latest articles...