Brazil’s jailed former president Jair Bolsonaro was recently reported to have undergone three medical treatments to stop a bout of persistent hiccups. While hiccups are usually harmless and short-lived, his case highlights a condition that can, in rare circumstances, become medically significant.
Hiccups are one of the few bodily functions named after the sound they make. The sound is caused by a sudden, involuntary spasm of the diaphragm – a large, dome-shaped muscle that separates the chest from the abdomen and plays an essential role in breathing.
When the diaphragm contracts unexpectedly, air is drawn rapidly into the lungs. At the same time, the vocal cords snap shut, producing the characteristic “hic” sound.
Most people hiccup between two and 60 times per minute. Episodes typically last a few minutes, sometimes a few hours, before resolving on their own. They are usually only a minor irritation.
Doctors become more concerned when hiccups persist. Those lasting longer than 48 hours are classified as “persistent”. If they continue for more than a month, they are described as “intractable hiccups” – a rare and often debilitating condition.
The causes of common, short-term hiccups are usually straightforward. They can be triggered by an overfull stomach, alcoholic or fizzy drinks, very hot or very cold drinks, or emotional states such as anxiety and excitement or stress. These factors irritate or stimulate the nerves involved in the hiccup reflex, briefly disrupting the normal control of breathing.
Given how common hiccups are, it is not surprising that there are countless suggested cures. Some are supported by scientific evidence, while others rely on anecdote and personal experience.
Many of the techniques that appear to work best have one thing in common: they affect how the diaphragm functions. By altering breathing patterns or briefly increasing carbon dioxide levels in the blood, they may help reset the nerves that control the muscle.
Several small studies have examined structured breathing techniques. One approach, called “hiccup-relief using prolonged active inspiration” – slowly breathing in very deeply and holding it to stop diaphragm spasms – showed success in 21 patients. Another technique, called supra-supramaximal inspiration (breathing in even more after you already feel completely full of air) relieved hiccups in six people in a separate study.
A device based on similar principles, using controlled sucking and swallowing to regulate diaphragm activity, demonstrated a nearly 92% success rate in over 200 people.
There are also many commonly cited home remedies, although these often have little or no evidence to support them. They include breathing into a bag, drinking or gargling iced water, pulling the tongue, biting a lemon, eating peanut butter, applying pressure to the eyeballs, rectal massage (yes, really), performing the Valsalva manoeuvre (trying to breathe out against a closed nose and mouth), or attempting to induce a sudden fright. However, for most people, a brief change in breathing or swallowing is enough to interrupt the hiccup reflex.
VikaNorm/Shutterstock.com
One reason hiccups are difficult to study is that they usually resolve quickly. Short episodes are hard to capture in controlled research settings, which limits large-scale studies. As a result, most published studies focus on persistent and intractable cases.
Intractable hiccups are rare, affecting about one in 100,000 people. They occur far more often in men, who account for more than 90% of cases, particularly those over the age of 50. In these people, hiccups can be exhausting and distressing, interfering with eating, sleeping and breathing.
In Bolsonaro’s case, the cause of his latest episode has not been made clear. In June 2021, however, he attributed a previous bout of persistent hiccups to medication prescribed after dental surgery. Although the specific drugs were not disclosed, several medications are known to trigger prolonged hiccups.
Corticosteroids, such as dexamethasone and methylprednisolone, particularly at high doses, are well-recognised triggers.
Unlike food or fizzy drinks, which irritate nerves directly, these drugs affect chemical messengers within the nerve pathways that control the diaphragm. Hiccups have even been reported following corticosteroid injections into the knee or shoulder, which are often given to relieve pain from arthritis.
Benzodiazepines (drugs to treat anxiety and insomnia) can also cause hiccups, sometimes even at low doses. Studies of procedures involving benzodiazepine sedation, such as endoscopy, show that around one in five patients given midazolam develop hiccups, compared with about one in 20 who are not given the drug. The effect is again more common in men.
Some antipsychotic medications, including aripiprazole, have also been linked to hiccups, which often resolve when the drug is stopped. These medications influence the same neurotransmitter systems involved in the hiccup reflex.
Not always benign
Treatment for persistent hiccups usually takes one of two forms: medication or physical procedures. The drugs doctors most often prescribe are baclofen and metoclopramide, which have been tested in small studies comparing them against placebos (dummy pills). If the medication doesn’t work or causes too many side-effects, doctors may consider more invasive treatments.
Bolsonaro underwent a phrenic nerve block, a procedure that temporarily reduces or paralyses the function of the phrenic nerve, which controls the diaphragm. The effect can last for hours, days or up to a few weeks.
Because the phrenic nerve plays a critical role in breathing, the nerves on both sides of the body are rarely blocked at the same time. When used appropriately, the procedure is highly effective.
In more severe cases, or when doctors find out what’s causing the problem, permanent treatments might be needed. These could include destroying the nerve that’s causing the hiccups using heat or freezing, or surgically cutting and sealing off the nerve to stop the signals.
Persistent hiccups after stomach surgery are common. Since Bolsonaro was previously stabbed in the abdomen, this could be playing a role in his hiccup problem.
Damage to the area of the brain responsible for regulating hiccups can also play a role. One well-known example is Charles Osborne who holds the record for the longest continuous bout of hiccups – lasting 68 years from 1922 to 1990.
Research shows they can sometimes be an early symptom of cancers of the oesophagus, colon, kidneys, or conditions affecting the brainstem. Studies have also found that men diagnosed with persistent hiccups have higher rates of certain cancers in the following 12 months.
Thankfully for most people, hiccups remain a harmless inconvenience. However, hiccups that persist for several days without an obvious trigger should be assessed by a doctor.
Adam Taylor does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.
