If this time of year pushes your snack cravings in the direction of black licorice, be extra sure that you're eating the treat in moderation. The Food and Drug Administration (FDA) says if you’re 40 or older, eating two ounces of black licorice a day for at least two weeks could land you in the hospital with an irregular heart rhythm or arrhythmia.

That's what happened in Ontario recently, where emergency room doctors were trying to solve the puzzle of a 51-year-old man who was rushed in with dangerously high blood pressure and low potassium.

His symptoms started with several days of abdominal pain, which led to vomiting and a loss of appetite, reports the National Post. By the time he had reached the ER, his potassium levels were so low that he was at risk of developing life-threatening heart rhythms. Doctors were stumped because the patient had no history of hypertension or any other medical conditions that would put him in this predicament.

After taking an in-depth medical history, they discovered the man ate a bag of licorice candies every day. In fact, he ate 50 of the jelly beans daily and continued to eat them, even when he was being treated in the hospital.

When doctors advised him to quit his licorice candy habit, his blood pressure and potassium returned to normal levels. If the medical team hadn't discovered the cause of his issues, he probably would have stayed on drugs the rest of his life, endocrinologist Tamara Spaic from London’s Western University told the National Post.

“He would likely require long-term anti-hypertensive treatment,” said Spaic, who helped with the case. “There would likely be a need to use multiple medications, which would increase the risk of developing various side effects, as well as the unnecessary high cost of treatment and regular followups.”

The case report on this jellybean licorice mystery was recently published in the journal Postgraduate Medicine.

Medical history of licorice

Licorice is an extract from the root of a woody shrub Glycyrrhiza glabra, which grows in subtropical climates. The plant contains glycyrrhizic acid (GZA) and has ancient origins in traditional and herbal medicine. In Egypt and China, it was used to treat many ailments, according to Medscape, including coughs, stomach ulcers, liver disease and constipation.

There's some evidence that licorice might be helpful for heartburn, eczema and cough and intubation issues after surgery, reports WebMD. Few of its other medical uses, however, have any medical evidence to support the claims.

What is 'licorice poisoning'?

Not only does licorice sometimes do no good, sometimes it can do harm. As in the case in Ontario, consumption of large doses of GZA in licorice or licorice extract can lead to dangerously lower levels of potassium (hypokalemia) and serious hypertension. This syndrome is known as hypermineralocorticoidism or occasionally "licorice poisoning."

Other symptoms can include weakness and headache, swelling and muscle spasms. Symptoms typically go away once you stop eating licorice.

The FDA is offering this advice for snacking with caution:

  • Don’t eat large amounts of black licorice at one time.
  • If you have been eating a lot of it and have an irregular heart rhythm or muscle weakness, stop eating it immediately and contact your doctor.
  • Black licorice can interact with some medications, herbs and dietary supplements. Check with your doctor if you have questions about possible interactions.

Most licorice-flavored foods that are sold in the U.S. don't contain GZA, so they don't trigger the same dangerous symptoms that might be produced by long-term use of lots of natural licorice.

Recently, a team of researchers in Chicago and Egypt studied "licorice abuse" and reviewed its possible health benefits and possible dangers. Their work was published in the journal Therapeutic Advances in Endocrinology and Metabolism. They concluded, "We aim to send a warning message that licorice is not just a candy and that serious life-threatening complications can occur with excess use."

So maybe it's better if you stick to chocolate.

Editor's note: This story has been updated since it was originally published in April 2017.

Mary Jo DiLonardo writes about everything from health to parenting — and anything that helps explain why her dog does what he does.