Stronger forms of marijuana include: sinsemilla (sin-seh-me-yah; a Spanish word), hashish ("hash" for short), and hash oil.
All forms of marijuana are mind-altering. In other words, they change how the brain works.
All forms of marijuana contain THC (delta-9-tetrahydrocannabinol), the main active chemical. They also contain more than 400 other chemicals. Marijuana's effects on the user depend on the strength or potency of the THC it contains.
The potency of marijuana has increased since the 1970s but has been about the same since the mid-1980s, according to the National Institute on Drug Abuse.
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National Institute on Drug Abuse. "Want to Know More?- Some FAQs about Marijuana." Marijuana: Facts for Teens Updated October 2013
National Institute on Drug Abuse. "Marijuana." Research Report Series Updated July 2012
The Partnership at DrugFree.org. "Marijuana." Drug Guide. Accessed April 2014.