In several places, the recreational use of marijuana by individuals 21 and older has been legalized as public opinions about the drug have softened. But it’s important to remember the health effects of frequent use. There are some long-term negative and positive effects that medical professionals and therapy experts have noted. According to Aaron Weiner, a cognitive behavioral therapist and addiction counselor in Lake Forest, Illinois, the severity of long-term marijuana usage is greatly influenced by the age of the user and the potency of the marijuana being consumed. The effects of marijuana use are worse the younger a person is when they first start using it and the stronger the THC concentration.