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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.

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 Departmnet of Public Health’s resources here.

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

San Mateo County Frequently Asked Questions

As San Mateo County obtains new information about how this new industry will be incorporated locally and by the state, updates will be posted on this webpage. Please also check the links provided below for the latest information available. (Revised 11/15/2016)

1. What happens after passing of Proposition 64?

Personal recreational use: Adults 21 years or above will be able to use recreational marijuana and grow marijuana for personal use immediately.

Commercial marijuana cultivation, manufacturing or sales operations: Requires a license from the State Bureau of Medical Cannabis Regulation, which is planning to begin accepting applications January 1, 2018.  A license from the state is required before any commercial cultivation, manufacturing or sales are allowed.

Please see detailed information regarding Proposition 64 here.

2. Who will issue licenses for marijuana businesses?

3. Does my city or county allow growing and selling of marijuana or manufacturing products with marijuana?

Proposition 64 gives cities and counties the option to either allow or restrict marijuana businesses. Please contact your local city (or county, if in the unincorporated area) directly to verify what the current local policies are on marijuana businesses. Details are currently being developed by cities and counties, with most planning to finalize any local requirements by January 1, 2018. If commercial operations are allowed locally, a license will also be required by the appropriate state agency (see above).

4. If my city/county doesn’t allow the growing and selling of marijuana, can I buy marijuana from another city/county?

Yes. Under Proposition 64, adults 21 years and older can buy marijuana from a licensed facility.

5. Do I need a license to grow marijuana for personal use?

No. Proposition 64 allows individuals to grow marijuana for personal use (up to six plants) without a license. However, your city or county may have additional restrictions and/or requirements. Periodically check your city’s or county’s website for any restrictions or additional requirements.

6. Can I sell homegrown marijuana plants or marijuana products to others?

No. Proposition 64 does not allow the sale of homegrown marijuana, whether whole plant, clippings, clones, or any product derived from any part of the plant.

7. What should I do if I am staying at an apartment complex or hotel and I smell marijuana from my neighbor’s unit?

Proposition 64 does not allow smoking marijuana in locations where smoking tobacco is prohibited. Contact the management company or the owner for any concerns related to marijuana use at the property.

8. What should I do if I smell marijuana from my neighbor’s house?

You may contact the local law enforcement agency or code enforcement agency for questions or concerns regarding marijuana use at private homes.

9. Who do I contact if I have other questions about marijuana?

You can contact San Mateo County Environmental Health Services at or contact your local city.  Remember that cities, counties and the state departments in charge of implementing Prop 64 and other marijuana-related legislation are still looking for answers and setting up programs to support this new industry and the community. Continue to check websites for updates.

10. Can I smoke marijuana or consume marijuana products while driving?

No. Proposition 64 prohibits driving under the influence of marijuana. It also prohibits smoking or ingesting marijuana, or even possessing an open container or package of marijuana, while driving or riding in a motor vehicle.

11. Can I smoke marijuana or consume marijuana products in public places?

No. Proposition 64 does not allow smoking or ingesting marijuana in public places, which includes but is not limited to hallways and lobbies of apartment buildings and hotels, on the street, in schools, amusement parks, public parks and places of business usually open to the general public.

12. Where can I buy marijuana for recreational use?

Currently there are no retail or manufacturing business that have been approved for selling recreational marijuana in San Mateo County. However, if you are a California resident with a Medical Marijuana Card, you can purchase marijuana at any licensed dispensary in California.

13. How much marijuana can I buy for recreational use?

Under Proposition 64, adults 21 years and older can possess, transport, or purchase up to one (1) ounce of marijuana and up to eight (8) grams of marijuana concentrates.