Ciguatera is a global human disease caused by the consumption of contaminated fish that have accumulated the sodium channel activator toxins known as ciguatoxins. These toxins activate the opening of voltage‐dependent sodium channels at hyperpolarizing membrane potentials, producing cell membrane depolarization at rest, mainly by increasing sodium influx. In humans, symptoms of ciguatera fish poisoning include paraesthesiae, dysaesthesiae and heightened nociperception, as well as sensory abnormalities such as metallic taste, pruritus, arthralgia, myalgia and dental pain. Some of the neurological symptoms produced by ciguatoxins in humans persist for months, or even years; however, the underlying cellular alterations for these symptoms are yet unknown. In this chapter, we review the main cellular effects of ciguatera toxins.