Other potential side effects include low blood pressure, lightheadedness, and drowsiness, but these have typically only occurred in patients who have exceeded doses of 1,500 mg daily for a period of 4 weeks or more; far more than the average person will need take on a daily basis for chronic pain symptoms. (In fact, the majority of CBD users claim they find an effective dose to be anywhere between 10 and 40 mg daily).
According to the United States Department of Health and Human Services, there were 455,000 emergency room visits associated with cannabis use in 2011. These statistics include visits in which the patient was treated for a condition induced by or related to recent cannabis use. The drug use must be "implicated" in the emergency department visit, but does not need to be the direct cause of the visit. Most of the illicit drug emergency room visits involved multiple drugs. In 129,000 cases, cannabis was the only implicated drug.
In this report, researchers reviewed 16 previously published studies testing the use of various cannabis-based medicines in the treatment of chronic neuropathic pain and found some evidence that cannabis-based medicines may help with pain relief and reduce pain intensity, sleep difficulties, and psychological distress. Side effects included sleepiness, dizziness, mental confusion. The authors concluded that the potential harm of such medicines may outweigh their possible benefit, however, it should be noted that the studies used a variety of cannabis-based medicines (e.g. inhaled cannabis and sprays and oral tablets containing THC and/or CBD from plant sources or made synthetically), some of which are more likely to result in these side effects than products without THC.