Hiccups are caused by an involuntary contraction of the diaphragm, the muscle just under the chest that helps with breathing, according to the Mayo Clinic. The contraction makes the vocal cords close, which causes the sound of a hiccup.
The primary causes for hiccups include eating a large meal or drinking alcohol, Mayo Clinic reports. Sometimes people develop hiccups after experiencing sudden excitement. Other causes, according to WebMD, including smoking, swallowing air or extreme change in stomach temperature from consuming something very hot followed by something very cold. Occasionally hiccups are an indicator of a more serious medical condition.
Most of the time, hiccups stop after a few minutes to a few hours, WebMD states. Though it happens only rarely, hiccups can last more than 48 hours. This condition is known as persistent hiccups. If they last more than a month, they are called intractable hiccups. Both of these conditions are very rare and need to be checked out by a doctor to determine the underlying cause.
Common hiccups can be cured by a number of home remedies that increase the blood's carbon dioxide level, WebMD says. Treatments include quickly drinking a glass of water, holding the breath for 10 or more seconds, and eating a teaspoon of sugar or honey.