Three field studies are widely cited which show no significant differences in abnormalities between heavy marijuana users and non-users. The sample sizes in the studies were small. The subjects were young and otherwise healthy c. There is a possibility of long term adverse effects that did not show up in those studies. Cardiovascular effects are common side effects.
Eyes redden due to dilation of the vessels in the cornea.
There are no known adverse permanent effects, but those with heart problems should avoid using marijuana. The most severe side effects are respiratory, due to chronic smoking of marijuana. A single joint can have as much tar as two packs of cigarettes. Carbon monoxide in the smoke impairs the blood s ability to carry oxygen, which compromises the oxygenation of an embryo or fetus. THC can produce panic reactions, paranoia or terror.