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Let’s Talk Cannabis

General information

You probably have lots of questions about the effects of marijuana. We can answer some of those questions, but it’s also a good idea to talk to your doctor.

What’s legal for adult use?

Under California law, adults 21 or older can use, carry, and grow cannabis (marijuana). Find more about what’s legal here

Since marijuana is still illegal under federal law, there is very limited research about long-term health effects of moderate or prolonged use. Additionally, most of the research that has been done uses a type of cannabis that is not reflective of the product on the market today.

There are very real health concerns, and these concerns are greatest for our vulnerable populations, like pregnant and breastfeeding women and young people. A specific concern is the potential for overconsumption of edibles because of the delayed effects, particularly among novice users. Another concern is the potential for accidental ingestion and poisoning of children.

Click here for what you should know to help you avoid harming yourself and others.

What are the risks for pregnant and breastfeeding women?

For pregnant and breastfeeding women, we want to discourage and delay cannabis use. We know tetrahydrocannabinol (commonly referred to as THC) passes to the fetus through the placenta and to infants through breast milk. Find out about the risks here.

What should you know about youth and marijuana?

Using marijuana daily can lead to changes in your brain. Research shows that when young people use marijuana, their memory, learning and attention are harmed. The marijuana available today has much higher tetrahydrocannabinol (THC) concentrations than cannabis from years ago. We want to prevent and delay cannabis use among youth because their brains are still developing. Find out more here.

San Mateo County is developing a youth marijuana education campaign. Read about it here.

How can parents and mentors make an impact?

Parents and mentors can have an impact on whether or not youth use marijuana. Pre-teens, teens and youth in their early 20s often seek out new experiences and engage in risky behaviors, such as using cannabis. You can help prevent underage use by starting the conversation about cannabis with youth in your life, and make sure they are aware of potential consequences. Find resources here


There’s a lot to learn about marijuana now that it is legal in California. For additional information about cannabis regulations, health and research, check out the California Department of Public Health’s resources here.

To find more information on San Mateo County regulations and the County Cannabis Cultivation Ordinance, visit: