Not putting things in your ear is a good rule to live by. That includes Q-tips, wax removal tools and ear candles – which, we know, don’t technically go inside the ear canal but they can release wax that does. Ear candles don't, by the way.

Indeed, the American Academy of Otolaryngology's advice is to avoid putting anything smaller than your elbow in there unless you want to risk hearing loss or a perforated eardrum. Though how exactly you’d get anything bigger in there is anyone’s guess.

A less well-known side effect of sticking things in your ear is an automatic coughing reflex – nicknamed “Arnold’s ear-cough reflex” after the man who first described it, Friedrich Arnold, a 19th-century German scholar.

So, what exactly does your ear canal have to do with coughing?

It all comes down to your vagus – the long nerve that stretches from your brain to your torso, linking to the heart, lungs, and other organs along the way. It touches the top of your ear, helps control your larynx, and extends to your stomach and lower intestines. Appropriately, like the word “vagabond”, its name stems from the Latin for “wandering”.

The vagus nerve performs all sorts of essential functions that enable you to go about your day-to-day life, from talking to eating to breathing to peeing – and yes, controlling your cough reflex.

The particular section that extends to your ear canal is called Arnold’s nerve and it is responsible for processing the sense of touch. If anything finds its way into your ear – whether that is a Q-tip or a lost cockroach – it will stimulate Arnold’s nerve.

Bizarrely, this stimulation can also cause you to cough on cue. This is an example of a biological glitch, or mix-up. The brain gets confused and mistakes contact in the ear for something in the throat, prompting you to cough in a misguided attempt to remove the irritant. 

"Arnold’s Nerve is a nerve that can carry touch sensation from the ear canal to the brain, however, because the nerve is connected to a nerve that goes to the throat, the brain may not know where the sensation is coming from, and interprets the sensation as something in the throat that needs to be coughed out," Dr Erich Voigt, an otolaryngologist at NYU Langone Health, told IFLScience.

It works in reverse too.

"Similarly, an irritation in the throat such as a viral ulcer or cancerous tumor may be felt as pain in the ear because the glossopharyngeal nerve will send those sensations back to the brain, but the brain does not know where the sensation came from and interprets this as ear pain," Voigt continued.

"I have found deep base of tongue and throat cancer in people who came to me complaining of ear pain as the presenting symptom. When I examined the ear, it was normal, so I examined the base of tongue and throat with my laryngoscope and found the cancer there."

Back to the ear-cough reflex. The exact amount of pressure needed to trigger this response will vary from person to person.

"The cough reflex may be triggered very easily in some people with a light touch stimulation, while in others, it may only be triggered by deep firm pressure or touch," said Voigt.

Researchers tested this rather odd phenomenon in a 2017 study by tickling the external auditory canal of adults and children with and without chronic cough using a Q-tip. The stimulation triggered Arnold’s ear-cough reflex in 25 percent of adults and 3 percent of children with chronic cough. Yet, just 2 percent of adults and children without.

The results of this study suggest that Arnold’s ear-cough reflex is possible but not particularly common in people without chronic cough. This, the researchers think, comes down to a condition that causes the vagus nerve to become hypersensitive (cough hypersensitivity syndrome, or CHS), which may be acquired by a viral respiratory infection or something in the environment.

It is still very rarely the cause of chronic cough, but there is increasing evidence to suggest that both chronic and idiopathic cough may, in many cases, be related to damage in sections of the vagus nerve. For example, one common side effect of vagus nerve stimulation, a treatment for epilepsy, is coughing. What’s more, there is reason to think that the sound and pattern of the cough may vary depending on where exactly that damage is.

All of which goes to show, the body is interconnected in surprising ways. So much so that an apparently unrelated event in the ear can have (some of) you in coughing fits.