Japanese site Netallica put the question before a otolaryngologist to see if the ear, nose, and throat doctor could confirm whether or not sexual arousal causes bloody noses.
The notion that arousal or excitement induces bloody noses (hanaji or “鼻血”) isn’t just part of anime or manga iconography.
In anime and manga, when characters get excited—often sexually excited—blood dribbles, or squirts, out of their noses.
According to Dr. Kanaya, “The notion that sexual arousal causes the heart rate and blood pressure to rise is something that’s a well documented fact; however, in actuality, sexual arousal and bloody noses have no direct connection.”