Why are weed unhealthy?

Cannabis dangers. Scientific studies, albeit mixed raised concerns about chronic marijuana use causing: non-resorative sleep, anxiety/ panic attacks in some, paranoia/psychotic thinking, diminished comprehension, impaired memory, lack of motivation, impaired driving, work-related accidents. It is addictive and causes withdrawal when abruptly stopped after chronic use.
Which weed? Marijuana when smoked can stun the lungs immune system and predispose to infection and allergy reactions in the airways. Regular weeds(not cannabis) are a frequent cause of allergies in certain windy dry parts of the country.