Black liquorice could kill you if you love it too much

It’s the popular black tangy treat loved by Australians and derived from a herb touted for its many health benefits. 

But liquorice has a deadly dark side: it could kill you, if you love it a touch too much. 

Despite its unsuspecting, aromatic, sweet taste, glycyrrhizin – the chemical in black liquorice that gives the candy its signature flavour – can have toxic effects when consumed in large quantities.    

In excess, glycyrrhizin throws out the fragile balance of chemicals that keep humans’ bodies running, leading to a hypertension crisis, muscle breakdown – or even death. 

Liquorice overdoses have been reported around the world, including the death of a 54-year-old American man in Massachusetts in September 2020. 

Liquorice may be a popular treat – but over indulging in the sweet tangy treat can have fatal consquences 

Professor of pharmacology and toxicology Bill Sullivan said adverse reactions are most frequently seen in people over the age of 40 who are eating far more black liquorice than the average person.

‘In addition, they are usually consuming the product for prolonged periods of time,’ Professor Sullivan wrote in the Australian Financial Review.

‘In the most recent case, the Massachusetts man had been eating a bag and a half of black liquorice every day for three weeks.’

Sodium and potassium are key in the body’s delicate ecosystem of chemicals that serve to maintain vital functions, working together in cells to drive communication between nerves and the contraction of muscles.

Glycyrrhizin mimics the hormone aldosterone, Professor Sullivan explained, which is made by the adrenal glands when the body needs to retain sodium and excrete potassium. 

In higher concentrations, glycyrrhizin can disrupt the balance of sodium and potassium, which can lead to elevated blood pressure, an irregular heart rhythm, muscle pain, numbness, and headaches. 

In the fatal Massachusetts case, the man was later found to have perilously low potassium levels, a side effect of glycyrrhizin poisoning. 

Professor Sullivan said it was important to note not all liquorice-based foods contain liquorice, with some using non-dangerous flavouring substitute anise oil.

The core chemical in black liquorice – glycyrrhizin – can disrupt the body’s fragile balance of sodium and potassium, leading to serious health conditions, such as heart arrythmia and high blood pressure

Products containing liquorice, a flowering plant native to parts of Europe and Asia, will say so on packaging, listing liquorice extract or glycyrrhizin acid among the ingredients. 

Some liquorice-flavoured treats, like black jelly beans or Good and Plenty, contain both anise oil and liquorice extract.

However, red-liquorice lollies, despite their name, are typically cherry or strawberry flavoured and are usually not infused with liquorice extract. 

And there are several hidden dangers that may increase the risk of the sweet treat turning toxic for lolly fanatics. 

For one, glycyrrhizin (which is the scientific name for liquorice), is 50 times sweeter than sugar and often used in an array of products, including soft drinks, teas, throat lozenges, and tobacco, making it difficult to track consumption levels. 

The ubiquitous ingredient is also found in dietary or health supplements, bolstering  the risk for those also eating the lolly.

However, experts say there is no need to ban the treat altogether, instead advising people to monitor intake

However, experts say there is no need to ban the treat altogether, instead advising people to monitor intake 

However, though glycyrrhizin has long been used as a remedy for many health issues, including heart burn, stomach troubles, sore throats, and coughs, there is insufficient evidence supporting its efficiency in treating any medical condition.

People with certain pre-existing conditions, like heart arrhythmia or high blood pressure, or taking potassium-lowering medications are also more susceptible to black liquorice overdose.

Despite the possible side effects, Professor Sullivan said there was no need for liquorice lovers to ban the sweet from their diet altogether. 

‘Eaten in small quantities from time to time, liquorice poses no significant threat to otherwise healthy adults and children. But it is advisable to monitor your intake,’ he wrote.

‘Next Halloween, be sure to remind your kids that candy is a “sometimes food”, especially the black liquorice.’


Black liquorice is made with extract from root of the Glycyrrhiza glabra plant that gives the candy its sweetness.

The root contains a compound called glycyrrhizin.

Glycyrrhizic acid keeps the body from properly absorbing potassium, so when you consume too much glycyrrhizin, potassium levels may drop below normal levels.

The balance between potassium and sodium levels is key to healthy heart functioning.

When potassium levels are too low, sodium levels are correspondingly too high.

The imbalance can result in high blood pressure and upset the heart’s rhythm.

Abnormal heart rhythms greatly increase the risk of heart attack.