In healthy volunteers, 2-hour infusion of VIP induced nausea and photophobia only in 33% and 8% of participants, respectively.19 None of the healthy volunteers reported phonophobia.19 At the same time, the dose-related side effects, such as flushing, warm sensations and heart palpitations, were very similar between the 2 study populations (Table 2). This evidence concerns the gene VIP and Phonophobia.