CNR1 and Vertigo: Several additional CNS-specific side effects associated with indomethacin use but not other NSAIDs, such as headache, vertigo, and dizziness, blurred vision, and psychosis following prolonged use, may be explained by the drug’s modulation of the endocannabinoid system and/or CB1R (Wiley et al., 2006; Parvathy and Masocha, 2015).