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:
- 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.
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].
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.
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.
- Page last reviewed: January 26, 2017
- Page last updated: January 26, 2017
- Content source: