The data are weaker, but also promising for muscle spasticity. The least promising categories are movement disorders, epilepsy and glaucoma. Most studies on adverse effects are based on smoked marijuana. Smoked marijuana is a crude cannabinoid delivery system that delivers a variable mixture of cannabinoids and other substances, including harmful ones. Psychological effects such as anxiety reduction, sedation and euphoria are potentially undesirable for certain patients and situations and beneficial for others.
More research is needed on their relation to medical benefits.
Marijuana smoke, like tobacco smoke, is associated with increased risk of cancer, lung damage and poor pregnancy outcomes. Certain sub-populations may be at higher risk of chronic effects. Adverse effects of chronic THC use appear to be quite minimal. Marinol, the oral medicinal form of THC, has not been found to lead to dependence. A related concern is the issue of association with other substance abuse.