What is 420?

Last Updated: Tuesday, April 20, 2021

marijuana leafApril 20, also known as “420,” is a day popular with many marijuana smokers. They see this date as an unofficial holiday and celebrate by getting high.

The term “420” originated in the 1970s with a group of California high schoolers who would regularly meet after school at 4:20 p.m. to smoke weed. 

Since then, the amount of THC in marijuana has increased significantly. Higher levels of THC can mean an increased risk for addiction if people are exposing themselves to high doses. 

420 on the Road 

Unfortunately, according to a 2018 study, fatal car crashes spike on that date each year. 

Even in states that have legalized marijuana for recreational use, driving while under the influence of the drug is still illegal and can be very dangerous. 

Marijuana slows reaction time, impairs a driver’s concentration and attention, and reduces hand-eye coordination. Learn more about drug-impaired driving.

Health Effects 

Besides the short-term effects of marijuana use like lung irritation and increased heart rate, teen marijuana use – whether it’s through smoking, vaping or edibles – can also have long-term effects on the brain.  The earlier someone starts using the drug, the more likely they are to develop a substance use disorder, according to research. 


As parents and educators, it’s important to know how the peer pressure around “420” can affect your teen. Talk to them regularly about how drugs can harm their bodies and their growing brains. Get tips on how you can start the discussion.


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