The effects on each person depend on the user's experience, as well as: how strong the marijuana is (how much THC it has); what the user expects to happen; where (the place) the drug is used; how it is taken; and whether the user is drinking alcohol or using other drugs.

Some people feel nothing at all when they smoke marijuana. Others may feel relaxed or high. Sometimes it makes users feel thirsty and very hungry - an effect called "the munchies." Some users suffer bad effects from marijuana. They may suffer sudden feelings of anxiety and have paranoid thoughts. This is more likely to happen when a more potent variety of marijuana is used.

If someone is high on marijuana, he or she might seem dizzy and have trouble walking; seem silly and giggly for no reason; have very red, bloodshot eyes; and have a hard time remembering things that just happened. When the early effects fade, over a few hours, the user can become very sleepy.