Details of delusional parasitosis vary among sufferers, but it is most commonly described as involving perceived parasites crawling upon or burrowing into the skin, sometimes accompanied by an actual physical sensation (known as formication). Sufferers may injure themselves in attempts to be rid of the parasites.
Perhaps one of the earliest trials in 1982, gave participants a dose of THC (1 mg/kg), followed by either a dose of valium or of CBD (0.5 mg/kg). The results suggested that CBD had a counteractive effect on THC stimulated anxiety.
Chronic high doses of up to 1500 mg per day are well tolerated and produce no noticeable physiological effects. However, there is evidence to suggest that the medical benefits of CBD disappear when dosages become excessive. For inhaled medical use, most users prefer varieties with THC:CBD ratios between 2:1 and 1:2. Extremely low-THC varieties are useful for making CBD extracts and tinctures.