Marijuana and Public Health

Marijuana is the most commonly used illegal drug in the United States, with 22.2 million users. Other common names for marijuana are weed, pot, or cannabis.^a

We know that marijuana use may have a wide range of health effects on the body and brain.

We have strong evidence that marijuana use may lead to:

• Addiction.^b
• Breathing problems, including inflammation of the airways and symptoms of chronic bronchitis, such as daily cough and phlegm.
• Short-term declines in memory, attention, and learning.
• Increased risk of poisoning among children.
• Increased risk for low birth weight in babies when a mother uses during her pregnancy [PDF 229KB].
• Increased risk for psychosis or schizophrenia.

Learn about the health effects of marijuana.

We have some evidence that marijuana use may also lead to:

• Increased risk for some types of cancer.
• Increased risk for heart attack and stroke.
• Decreased IQ—and this change in IQ can last a long time and may even be permanent.
• Less academic and career success [PDF 224KB].
• Lower income [PDF 224KB].
• Poor school performance [PDF 224KB].
• Increased risk for motor vehicle crashes [PDF 213KB].

Learn about the health effects of marijuana.

^a

Throughout CDC’s marijuana website, the term “cannabis” refers to the plants from the two commonly accepted Cannabis groups (i.e., taxa): Cannabis sativa (or Cannabis sativa subsp. sativa) and Cannabis indica (or Cannabis sativa subsp. indica). Please note that the technique of classification (i.e., taxonomic status) of Cannabis is unclear; thus, the two Cannabis taxa (inidica and sativa) can be ranked at the species or subspecies level.

^b

The term “addiction” is used to describe compulsive drug seeking despite negative consequences. However, we recognize that “addiction” is not considered a specific diagnosis in the fifth edition of The Diagnostic and Statistical Manual of Mental Disorders (DSM-5)—a diagnostic manual used by clinicians that contains descriptions and symptoms of all mental disorders classified by the American Psychiatric Association. Rather, the DSM-5 uses the term “substance use disorder.” However, throughout this document “addiction” is used synonymously with having a substance use disorder for ease of language recognition and understanding.