This is the first study to investigate the use of cannabis amongst patients with dizziness. This study suggests a general willingness in patients with dizziness from both central (CFVD) and peripheral vestibular pathologies (PVD) to utilize and learn more about cannabis therapy as a treatment option. Understanding patient attitudes toward cannabis is essential for researching its use in treating dizziness.

The endocannabinoid system (ECS) is essential for regulating pain, emotion, memory, neural protection, and reducing central hyperexcitability and inflammation [17,18,26,27]. This in part is controlled through the inhibition of endocannabinoid uptake, regulating CB1 receptors, and activating serotonergic receptors. In the central nervous system, endocannabinoids and cannabinoids bind to CB1 receptors, inhibiting the release of excitatory neurotransmitters and reducing neuronal hyperexcitability [26]. The effect of CBD on dizziness is partially thought to be due to the existence of CB1 and CB2 receptors in the vestibular nuclei [26]. The effect of a highly potent CB1 receptor agonist (CP-55) has demonstrated strong inhibition of medial vestibular nuclei neurons in guinea pigs, suggesting that CB1 receptors are located presynaptically and modulate neuronal excitability by reducing glutamate release [26]. Additionally, CB2 receptors have been seen in the medial vestibular and cochlear nuclei of rats [35,36]. The confirmation of functioning CB1 receptors in the vestibular nuclei along with the presence of CB2 receptors further substantiates the crucial role of the ECS in vestibular reflexes.

While effective in managing various medical conditions, a common concern with medicinal cannabis is the inconsistency of its regulation. Many products contain higher THC levels than federally permitted and less CBD than labelled, complicating clinical research due to strain variability and inconsistent THC:CBD ratios [37]. These discrepancies may contribute to variable side effect profiles, such as dizziness reported in some clinical trials [38,39,40,41]. It is theorized that dizziness from cannabis is due to its vasodilatory effects, resulting in postural hypotension [42]. However, this effect is shown to be transient, diminishing after 1–2 days of repeat exposure with tolerance. Nonetheless, our questionnaire did not capture this possibility in our patients consuming cannabis. Chronic users show a decrease in heart rate and disappearance of orthostatic hypotension [42,43]. Cannabinoid Hyperemesis Syndrome is an emerging gastrointestinal condition associated with frequent and long-term use of cannabis [44]. Its estimated prevalence of 3.43 per 100,000 based on emergency visits in Ontario, Canada, remains far lower than that of dizziness at 35.6% [1,45]. Accordingly, patients using cannabis to relieve symptoms of dizziness should be educated on the potential risks but not discouraged from its use without further individualized assessment and consideration of alternative treatments for their symptoms.

Variations in THC:CBD ratios and formulations may also play a role in inconsistent reports of dizziness with cannabis use. Whole plant cannabis with 12.5% THC was not associated with dizziness while sublingual sprays with similar THC:CBD ratios were [46,47]. In patients with migraine, THC:CBD combinations have been reported to provide greater pain relief and symptom freedom than other formulations. Given the overlap between migraine and vestibular migraine, these findings raise the possibility that similar cannabis formulations may also influence dizziness-related symptoms in patients with vestibular migraine [48]. This is further suggested by the fact that patients in the current study have interestingly reported noticeable differences in the effect of cannabis on their dizziness, owing to different formulations and THC:CBD contents. In order to accurately understand the role of cannabis in dizziness, standardization of cannabis formulation and content is imperative along with follow-ups to determine how its side effect profiles can change over time.

There is a well-established, likely reciprocal link between dizziness, depression and anxiety [8,14,15,49,50,51]. In our study, 52% of cannabis users reported doing so to manage emotional difficulties such as anxiety and stress [52]. Physical neurotologic conditions were found to induce psychiatric pathologies just as frequently as primary psychopathologies caused dizziness [52]. Neuro-otologic conditions were also found to worsen pre-existing anxiety and depression [52]. Though the pathophysiology linking vestibular symptoms and psychological distress is unclear, overlapping neuroanatomical regions and neurotransmitters seen in both the vestibular system and in emotional regulation are thought to be the cause [50]. Cannabis has been shown to reduce anxiety, depression, and pain, improve sleep and increase overall self-reported quality of life in those diagnosed with clinical anxiety and depression, and this was corroborated in the present study [53]. Given the bi-directional relationship between vestibular symptoms and emotional distress, the perceived benefits we observed may reflect modulation of concomitant mood or sleep symptoms rather than a direct vestibular effect.

Tinnitus and dizziness are common complaints that often pose a challenge for physicians to treat effectively [31]. The pathophysiology of both symptoms is thought to be related to neuronal hyperexcitability. In a similar study as the present one, 96% of patients with tinnitus (n = 45) demonstrated a willingness to try cannabis-related medications, with 80% of cannabis users finding an improvement of their tinnitus and 37.5% an improvement in dizziness symptoms [31].

This study has some limitations. Despite using a large and diverse sample, recruiting all patients from the same tertiary clinics with 72% being females may limit the generalizability of our findings. Given the referral pattern to the Ottawa Vestibular Program, there is likely a bias towards patients with more chronic and recalcitrant dizziness. While our results appeared comparable between the PVD and CFVD subgroups, the sample size in NVD was too small to make conclusions regarding the generalizability of our findings to non-vestibular dizziness populations. The etiology, duration of symptoms, and possibility of confounding comorbidities among our population is quite variable, which impacts treatment response, patient perceptions and desperation for treatment. Additionally, the social stigma surrounding cannabis use may have also deterred the participation of patients with reservations about cannabis, introducing a potential response bias skewing results toward a pro-cannabis stance with contributions of recall bias from the self-reported nature of the data [54]. Lastly, our study only evaluated the positive effect of cannabis on dizziness, without considering its negative effects. Because our study assesses attitudes and self-reported experiences without a control group, standardized products, or diagnostic stratification, our findings provide descriptive evidence that motivates future studies. Diagnosis-specific trials controlling for confounders such as the co-occurrence of mood, anxiety and sleep disorders with standardized formulations and safety follow-up are needed to understand the direct or adjunctive role of cannabinoids in managing dizziness.