Many people may have had the annoying experience of hiccups that do not seem to relent and make it difficult to breathe or speak. What is it that causes hiccups, and how can they be stopped?
According to Tsukasa Kondo, associate professor at Fujita Health University in Toyoake, Aichi Prefecture, hiccups are a phenomenon in which the diaphragm, which moves the lungs during respiration, contracts forcefully and causes rapid inhalation while at the same time the vocal cords are abruptly closed.
The role of hiccups is unclear, but there is a theory that says hiccups are the remnants of the structure that closes the trachea so as to prevent water from getting in the lungs when living things were in the process of transitioning from branchial respiration, or breathing with gills, to pulmonary respiration, or breathing with lungs, as they moved from the water to the land.
A “hic” sound is made when hiccuping. The “hi” part is said to be the sound of the vocal cords vibrating as they try to close rapidly, while the “c” is the sound of the breath stopping as the vocal cords are closed.
Why do the contraction of the diaphragm and the closing of the vocal cords happen at the same time? “The stimulus occurs in the hiccup center of the medulla oblongata, which is the command center for hiccups,” Kondo said.
Drinking carbonated beverages, eating hastily, laughing hard and coughing; these and other stimuli are transmitted to the hiccup center in the medulla oblongata through the glossopharyngeal nerve located in the throat.
The medulla oblongata then sends out two instructions simultaneously, one through the phrenic nerve for the diaphragm to contract, and the other through the vagus nerve for the vocal cords to close.
However, stimuli like these do not always cause hiccups to happen. This is because the hiccup center usually receives a message from the brain to keep hiccups from coming out, by way of a neurotransmitter called GABA, or gamma-aminobutyric acid.
“When the stimuli are stronger than the message to suppress, hiccups occur,” Kondo said. Another of the characteristics of hiccups is that once they start, they are difficult to stop quickly.
Drinking alcohol and taking certain kinds of medicine are some examples of things that decrease the ability to suppress hiccups. Also, as children are less developed than adults, suppression through GABA is less effective, and hiccups occur more frequently in children.
Hiccups will stop naturally, so putting it out of your mind and waiting is best. That said, in the event that you are supposed to be greeting people at a meeting or a party, or the hiccups have gone on for half a day and have become uncomfortable, Kondo has some advice: “If you can provide some sort of stimulus, the hiccups will stop more readily.”
Kondo’s recommended methods for stopping them are to place your index fingers firmly in both ears and push for 30 seconds, or to pull your tongue for 30 seconds.
“Both of these are thought to provide the stimulus to the glossopharyngeal nerve to suppress the hiccups,” he said.
Also effective is the well-known method of getting someone to surprise you. However, none of these are guaranteed to stop hiccups. Furthermore, people who have dealt with issues such as asthma, heart disease and stroke should avoid these stimuli.
If hiccups are prolonged, caution is necessary. If they last for 48 hours or longer, they are classified as “persistent,” while cases lasting over a month or longer are classed as “intractable.”
In cases of persistent or intractable hiccups, additional problems such as nausea, fatigue, labored breathing and insomnia can occur. There are also examples of people with intractable hiccups suffering from strokes or malignant tumors.
“Lifestyle issues such as combined smoking and drinking can have a [negative] effect, so it’s a good idea to reexamine your habits. In any case, if your hiccups last for over a month, please go for a consultation at a hospital,” Kondo said.