The short-term effects of hashish use include problems with memory and learning; distorted perception (sights, sounds, time, touch); difficulty in thinking and problem solving; loss of coordination; and increased heart rate, anxiety, and panic attacks. The effects may be more intense due to the high concentration of THC found in hash and other concentrates.

THC in marijuana is strongly absorbed by fatty tissues in various organs. Generally, traces of THC can be detected by standard urine testing methods several days after a smoking session. In heavy chronic users, traces can sometimes be detected for weeks after they have stopped using marijuana or its concentrates.

THC in hashish is many times more potent that the levels of THC found in standard marijuana. Levels of THC found in marijuana have skyrocketed over the last two decades. According to samples tested by the DEA, percentage of THC in marijuana has gone from roughly 4% in 1998 to over 15.5% in 2018.

The long term effects of hashish or marijuana concentrate use are not yet fully known; but, long-term marijuana plant-use has been studied.

• Psychological effects can include paranoia, anxiety, panic attacks, and hallucinations.
• Alterations in heart rate and blood pressure may occur.
• People who inhale THC products often have the same respiratory problems as cigarette smokers. These individuals may have daily cough and phlegm, symptoms of chronic bronchitis, and more frequent chest colds. They are prone to lung infections like pneumonia. Marijuana smoke may contain some of the same cancer-causing chemicals found in cigarette smoke (toxins and tar).
• Marijuana and THC affects memory, judgment and perception. Learning and attention skills are impaired among people who use marijuana heavily.

Studies show that marijuana use from a young age can affect brain development and IQ levels.