You have to have an adequate supply of DHA/fish oil, for the neurological benefits of the eCB system to work. R

In theory, smoking marijuana (activating CB1 receptors) early on in life may make you more anxious later on in life (by not letting your GABA receptors fully mature). This hasn't been proven in humans, only rats. R

Also, CBD can be immunosuppressive. R

So don't take it if you are immunocompromised.

Anyway, cannabinoid analgesics have generally been well tolerated in clinical trials with acceptable adverse event profiles. R

In humans, CBD has been shown to be safe in multiple small studies, suggesting that it is well tolerated at doses of up to 1500 mg/day orally or 30 mg intravenously. R R

In a study with 2811 users of cannabis with ADHD, users had more ADHD symptoms when not using cannabis. R

It is speculated that this may be THC in cannabis and not CBD, though. R R

In one study, CBD administration did not improve brain functions in piglets that lacked oxygen. R

Also, CBD when combined with THC may decrease/impair reward learning and motivation. R

There is some preclinical evidence to suggest that CBD may reduce THC clearance, modestly increasing THC in the body. This would result in more THC available to receptors, increasing the effect of THC in a dose-dependent manner. R R

The evidence for this in humans seems to suggest that this may not happen though. R

Cannabis dependence is associated with CB1R downregulation, which begins to reverse surprisingly rapidly upon stopping cannabis use and may continue to increase over time. R

Chronic THC use may decrease and blunt dopamine receptors (DRD1 and DRD2), since THC increases dopamine signaling. Although, it appears to be dose dependent. R

Also THC may cause schizophrenic-like symptoms, altered perception, increased anxiety, delayed recall time, impaired mental performance and increased cortisol in some. R

Fasoracetam may help with memory loss induced by cannabis.

Lastly, smoking cannabis at a young age may cause long term cognitive deficits. R