A bout of hiccups, in general, resolves itself without intervention, although many home remedies claim to shorten the duration, and medical treatment is occasionally necessary in cases of chronic hiccups. Hiccups are caused by many central and peripheral nervous system disorders, all from injury or irritation to the phrenic and vagus nerves, as well as toxic or metabolic disorders affecting the aforementioned systems. Hiccups often occur after consuming carbonated beverages, alcohol, dry breads, or spicy foods. Prolonged laughter or eating too fast are also known to cause hiccups. Persistent or intractable hiccups may be caused by any condition which irritates or damages the relevant nerves.