Table 3.

Incidence of AEs reported in the 6 studies in this review

STUDYDELTA-9-THC POTENCY, %DOSING FREQUENCYDELTA-9-THC POTENCY DOSE, mg/DAEs
MINIMUMMAXIMUMMINIMUMMAXIMUMNEUROCOGNITIVENONCOGNITIVE
Abrams et al,15 20073.563.563 times daily3232Mean side effect scores (95% CI) were as follows for cannabis group and placebo group, respectively:

  • 0.25 (0.14 to 0.44) and 0.10 (0.05 to 0.22) for anxiety

  • 0.54 (0.36 to 0.81) and 0.08 (0.04 to 0.17) for sedation

  • 0.16 (0.07 to 0.34) and 0.01 (0.00 to 0.04) for disorientation

  • 0.17 (0.07 to 0.39) and 0.01 (0.00 to 0.06) for confusion

  • 0.15 (0.07 to 0.31) and 0.02 (0.01 to 0.05) for dizziness

NR
Corey-Bloom et al,11 2012*441 time daily3232Dizziness, feeling “too high,” and headaches were all greater in treatment groupFatigue and nausea were higher in treatment group
Ellis et al,13 2009184 times dailyNRNRCombined UKU and DAIDS side effect (concentration difficulties, fatigue, sleepiness or sedation, increased duration of sleep) frequency was greater in cannabis group than in placebo group. There was a trend for moderate or severe AEs to be more frequent during active cannabis than placebo administrationIncreases in heart rate by ≥ 30 points were more frequent in cannabis group than placebo group
Ware et al,12 2010†2.59.43 times daily1.8757Of the total number of neurocognitive events, 15 of 91, 23 of 91, 23 of 91, and 30 of 91 reported AEs for 0%, 2.5%, 6.0%, and 9.4% delta-9-THC, respectivelyOf the total number of noncognitive events, 12 of 52, 13 of 52, 14 of 52, 13 of 52 reported AEs at site of administration for 0%, 2.5%, 6.0%, and 9.4% delta-9-THC, respectively; 5 of 28, 5 of 28, 7 of 28, and 7 of 28 for respiratory AEs, respectively; and 9 of 39, 9 of 39, 12 of 39, 9 of 39 for systemic and nonspecific AEs, respectively
Wilsey et al,9 2013‡1.293.538–12 puffs per sessionUnknown19.25§Feeling “high” or feeling “stoned” was greater in treatment groups and was dose dependent, but effect was relatively small. Feeling “anxiety” or feeling “down” was not prominent. Neuropsychological tests found psychomotor slowing in dominant hand and impaired learning or memory that was dose dependent, while delayed memory was not affected by delta-9-THC use. Effect sizes were generally small across groupsNR
Wilsey et al,14 20083.579 puffs per session19.25‖34‖Feeling “high” scored greatest for the high-dose group (P < .001) and both dose groups differed from placebo group (P < .05). Sedation occurred more in both dose groups compared with placebo group (P < .01). Cannabis produced significantly more confusion than placebo (P = .03). The 7% cannabis demonstrated evidence of neurocognitive impairment in attention, learning and memory, and psychomotor speed, whereas the 3.5% cannabis resulted in a decline in learning and memory only. When looking across at all measures, participants using 7% cannabis had greater impairment than those using 3.5% cannabis, who in turn had greater impairment than placebo participantsNR

  • AE—adverse events, DAIDS—Division of AIDS, delta-9-THC—delta-9-tetrahydrocannabinol, NR—not reported, UKU—Udvalg for Kliniske Undersøgelser.

  • ↵* There were 5 participants who withdrew from treatment owing to AEs including uncomfortable “high” (n = 2), dizziness (n = 2), and fatigue (n = 1).

  • ↵† Overall, 248 mild and 6 moderate AEs. Total number of AEs and number of participants reporting at least 1 AE increased with delta-9-THC potency.

  • ↵‡ While there were neurocognitive symptoms, there were generally small-medium effect sizes and the authors believed that they were not likely to affect daily functioning.

  • ↵§ Study authors were unable to comment on dose owing to flexible dosing (maximum assumes participant inhaled all medication in vaporizer).

  • ↵‖ Based on average cigarette weight.