What are the symptoms of using marijuana?

Many potentially. Possible effects of marijuana: anxiety, depression, fear, panic, delusions, hallucinations, losing touch with reality, inattentiveness, short-term memory problems, disturbances of thought processes. Fatigue, poor concentration, slowed reaction times & slowed problem solving.
OMG. Mj used over many years can lead to schizophrenia or similar disorders. Acutely, it impedes judgment and common sense. It causes dysmotivation and compromised cognitive skills. It is often implicated with other drugs in serious motor vehicle accidents. The major problem is that it takes up to 4 weeks for the mj to leave your brain, so its effects can last a long time.