Recently I was chatting to a neighbour - I'll call her Daisy - who had suddenly been diagnosed with high blood pressure for the first time in her life. I know Daisy. At the age of 85, she is thin, fit and active, and has always been like that. She works hard in her garden and walks every day. Why would her blood pressure suddenly go up?  We were discussing Christmas and she mentioned how much she had been enjoying her favourite treat, licorice, over the festive season.This rang alarm bells. "Do you eat licorice every day?" I asked. She admitted that due to the holiday season, yes, she had indeed been indulging herself. 

Warning: Don't eat licorice every day!

Licorice can cause dangerously high blood pressure, though most consumers don't know that, and most doctors don't think to ask.

Most people think of licorice as a treat or a health food, but licorice can contain high levels of a natural chemical called glycyrrhizinic acid. If consumed regularly, the result can be dangerously high blood pressure (hypertension) and dangerously low potassium levels (hypokalemia) (1).

"The daily consumption of licorice is never justified because its benefits are minor compared to the adverse outcomes ... Licorice is not just a candy. Serious life-threatening complications can occur with excess use" (2)

Man dies suddenly after eating licorice

A 54 year old Massachusetts construction worker who ate a bag and a half of black licorice every day for a few weeks collapsed while having lunch. Doctors found he had dangerously low potassium, which led to heart rhythm and other problems. Emergency responders did CPR and he revived but died the next day (3).

Possible symptoms of licorice toxicity

- heart, brain, kidney, vision and muscle problems including severe high blood pressure, low potassium levels, heart rhythm problems, paralysis, vision impairment acute kidney injury, muscle spasms (see more in Ref 2 and Table)
- dizziness, lightheadedness
- fatigue and muscle cramping
- dark urine
- weakness
- passing large amounts of urine
- oedema (swelling due to collection of fluid in body tissues)
- dyspnea (difficulty breathing due to pulmonary oedema, accumulation of fluid in the lungs)
- headache (due to high blood pressure)
- constipation
- depression, confusion
- heart palpitations
- paresthesias/dysesthesias (abnormal sensation, typically tingling, prickling, ‘pins and needles’ or burning sensations of extremities)
- increased risk of cognitive and behavioural problems such as ADHD, oppositional defiance and aggression to the babies of pregnant women who have a high licorice intake during pregnancy, see more below
- and others  - see case histories below. They range from seizures in a ten year old, to a pregnant 18 year old who loses her baby, to adults with impaired vision, paralysis and many more ...

Licorice during pregnancy linked to ADHD

Scandinavians consume a lot of licorice. A study in Helsinki, Finland, checked mothers' licorice intake (low, moderate or high).  Eight years on, they checked the children's cognitive abilities and behaviour. Children born to mothers who consumed high amounts of licorice during pregnancy had dose-related deficits on vocabulary and memory tests, and an increased risk of behavioural issues including aggressive behavior problems, attention deficit hyperactivity disorder and oppositional defiance, as well as physical problems that sound a lot like food intolerance (headaches, stomach aches, skin rashes, irritable bowel etc). It is thought this effect is due to glycyrrhizin from licorice impairing the placenta barrier and thus allowing stress hormones call glucocorticoids to enter the baby’s system. Mothers are warned to avoid licorice during pregnancy (4).

For people who are sensitive to salicylates

In the 1985 analysis of salicylate contents of foods by Swain et al (5), licorice was found to be extremely high in salicylates - approximately ten times higher than peppermints, which are already very high. Foods rated Very High in salicylates are considered likely to contain other problematic food chemicals as well.

In this reader story, a woman who frequently ate dried fruits - "because I thought they were healthy" -  would develop coughing caused by sulphite preservatives in dried fruit. She wrote:

I started to experience sudden uncontrollable coughing fits at the most embarrassing times, so always carried a packet of Fisherman's Lozenges to pop in my mouth on these occasions. I noticed that I started having heart palpitations which would last a short time, but got scared at times when they became stronger or lasted longer (I likened the feeling to my heart being like a washing machine out of balance) ... Eventually I linked these palpitations to the Fisherman's Lozenges and I haven't had any more palpitations since ceasing to take them. Now I am a lot wiser about the foods I eat and I am certainly a lot better for it. –  from story [692]

Fisherman’s Friend lozenges are made from all natural ingredients and do not contain preservatives. However, they do contain licorice.

References

1.Ceccuzzi G et al, Liquorice Toxicity: A Comprehensive Narrative Review. Nutrients, 2023 Sep 5;15(18):3866. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10537237/

2.Omar HR et al, Licorice abuse: time to send a warning message, Ther Adv Endocrinol Metab. 2012 Aug;3(4):125-38. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3498851/

3. Edelman ER, Butala NM, Avery LL, Lundquist AL, Dighe AS. Case 30-2020: A 54-Year-Old Man with Sudden Cardiac Arrest. N Engl J Med. 2020 Sep 24;383(13):1263-1275. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8568064/

4. Räikkönen K and others, Maternal licorice consumption and detrimental cognitive and psychiatric outcomes in children, Am J Epidemiol. 2009;170(9):1137-46. http://aje.oxfordjournals.org/content/170/9/1137.long#xref-ref-34-1

5. Swain et al, Salicylates in foods, 1985  http://www.fedup.com.au/images/stories/Swain1985.pdf  

Case reports

Man dies after eating bag of licorice every day for a few weeks. The Guardian https://www.theguardian.com/us-news/2020/sep/24/man-licorice-dies-massachusetts.

The story of a very fit woman who developed high blood pressure from drinking licorice tea from Blood Pressure UK. 0 https://www.bloodpressureuk.org/resources/real-stories/liquorice-tea-caused-my-high-blood-pressure--nikkis-story/

"I am a very healthy 50 year old ...  in a bid to get even healthier, I decided to stop drinking caffeinated tea in preference for herbal tea  ... you can imagine my disbelief, when at a periodic health check in December 2013, I was diagnosed with high blood pressure ..."  Hypertension induced by liquorice tea. Allcock E, Cowdery J .BMJ Case Rep. 2015 Jun 15;2015.

A 45-year-old woman presented to her general practitioner with a 4-month history of hot flushes, sweating and headaches. On examination, she was found to be hypertensive, and blood tests revealed mild hypokalaemia. While awaiting the results of further investigation into the cause of her elevated blood pressure, the patient conducted her own research and identified liquorice tea as the potential cause of her symptoms. The patient had been drinking up to six cups of liquorice tea per day as a substitute for caffeinated tea and fruit-based infusions. The patient immediately stopped consuming the drink and within 2 weeks her symptoms, hypertension and hypokalaemia had entirely resolved.

Licorice abuse: time to send a warning message Omar HR and others, Ther Adv Endocrinol Metab. 2012 Aug;3(4):125-38. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3498851/

A 35-year-old man from Egypt, with no past medical history, presented to the emergency room with progressive weakness that started in his lower extremities and quickly progressed to involve the upper limbs ... On further questioning, the patient admitted to drinking 1 liter daily of licorice, ‘erk soos’, during the whole month of Ramadan ... The potassium level normalized slowly over the next 10 days with a gradual return of his motor function.

Räikkönen K and others, Maternal licorice consumption and detrimental cognitive and psychiatric outcomes in children,  Am J Epidemiol. 2009;170(9):1137-46. http://aje.oxfordjournals.org/content/170/9/1137.long#xref-ref-34-1

The authors studied whether prenatal exposure to glycyrrhiza in licorice exerts detrimental effects on cognitive performance and psychiatric symptoms in 321 Finnish children 8 years of age ... Data are compatible with adverse fetal "programming" by overexposure to glucocorticoids and caution against excessive intake of licorice-containing foodstuffs during pregnancy.

Posterior reversible encephalopathy syndrome associated with licorice consumption: a case report in a 10-year-old boy. Tassinari D et al, Pediatr Neurol. 2015 Apr;52(4):457-9. http://www.ncbi.nlm.nih.gov/pubmed/25680999

We describe a child with high consumption of licorice toffees who developed systemic hypertension followed by posterior reversible encephalopathy syndrome. This 10 year old boy was hospitalized following a cluster of generalized tonic-clonic seizures   .... constant high blood pressure and a brain magnetic resonance scan showed a localized vasogenic edema; these symptoms suggested posterior reversible encephalopathy syndrome. He had been eating licorice toffees for a period of 4 months, consuming an estimated 72 mg of glycyrrhizic acid per day; this led to our assumption of the reason for his hypertension.

Severe, very early onset pre-eclampsia associated with liquorice consumption. Hauksdottir D et al, Hypertens Pregnancy. 2015 May;34(2):221-6. http://www.ncbi.nlm.nih.gov/pubmed/25774453

The case of an 18 year old healthy pregnant woman who lost her baby due to very early onset pre-eclampsia, possibly aggravated by liquorice consumption.

An Unusual Case of Licorice-Induced Hypertensive Crisis. Ottenbacher R, Blehm J, S D Med. 2015 Aug;68(8):346-7, 349. http://www.ncbi.nlm.nih.gov/pubmed/26380428

A 65-year-old woman with previously well controlled hypertension on a single medication presented to the emergency room with acute, symptomatic hypertension with blood pressures running 200s/140s ... She required a seven-day hospitalization (five of which were in the ICU) until her symptoms and hypertension were controlled with a three-drug regimen  ... She in fact was eating large amounts of Snaps licorice which uses its original 1930s recipe including licorice granules. Her licorice habit abruptly started six months prior and included a minimum of two to four boxes per day every day. Black licorice induced hypertension is an uncommon cause of hypertension in modern times because newer types of licorice rarely use the active ingredients in licorice root in large quantities. However, certain licorices and candies still contain glycyrrhizic acid (GZA) in sufficient quantities to affect blood pressure and cause other health issues.

Licorice as the cause of elevated blood pressure and headache? Pelttari H, Välimäki MJ.Duodecim. 2015;131(3):270-3. http://www.ncbi.nlm.nih.gov/pubmed/26245078

We describe a patient who sought medical advice from an endocrinologist for recurrent, severe and symptomatic hypertension. After the patient had stopped eating salmiac (salty licorice) and licorice, the headache that had persisted for years disappeared, fluctuations in weight stabilized and occasional edemas of the lower limbs vanished. Since the cessation of using licorice products normalized the blood pressure, it is likely that the patient had licorice-induced hypertension.

A hypertensive emergency with acute visual impairment due to excessive liquorice consumption. Schröder T et al, Neth J Med. 2015 Feb;73(2):82-5. http://www.njmonline.nl/getpdf.php?id=1542

A 57-year-old male patient presented to the Emergency Department with acute visual impairment. Initial examination revealed hypertensive retinopathy (damage to the retina cause by high blood pressure) ...  the patient had been consuming at least three packs of liquorice (each 300 g) from a German sweet manufacturer weekly for the past 3-4 months. Licorice consumption was stopped immediately. At first, seven different drugs were required to lower the blood pressure, finally resulting in substantial improvement in vision. After three  months, with the patient still not eating any liquorice and having treatment with two drugs, normal blood pressure was achieved.

A Unique Case of Licorice Lozenges Resulting in Hypertension and Hypokalemia. W Dai  et al, J Clin Hypertens (Greenwich). 2016;18(2):159-60. http://onlinelibrary.wiley.com/doi/10.1111/jch.12633/full

A 66-year-old man with a medical history of peripheral neuropathy and newly diagnosed hypertension was noted to have unexplained hypokalemia on routine laboratory tests ... he had been taking an unusually large amount of cough lozenges for the past 3 to 4 months in order to distract his attention from neuropathic pain. Interestingly, the ingestion of the lozenges coincided with his hypokalemia. He had been consuming approximately 160 tablets per day of a licorice-containing lozenge, “Fisherman's Friend––Extra Strong,” amounting to approximately 240 g of cough drops per day containing 288 mg of glycyrrhizin. For reference, the European Commission Scientific Committee on Food has proposed an upper limit of 100 mg/d of glycyrrhizin, which is found in approximately 60 g to 70 g of licorice candy.

The patient was advised to discontinue the consumption of these licorice-containing lozenges and to follow up with repeat tests in 6 weeks. At follow-up, the patient was again noted to be hypertensive ... He admitted to have cut down but had not stopped the lozenge intake (80 per day), which still contained higher-than-recommended levels of glycyrrhizin. Follow-up tests 7 weeks after cessation of the lozenges demonstrated complete resolution of the hypokalemia, metabolic alkalosis and hypertension.

Licorice-related rhabdomyolysis [breakdown of muscle tissue]: a big price for a sweet tooth. Shah M and others, Clin Nephrol. 2012 Jun;77(6):491-5.http://www.ncbi.nlm.nih.gov/pubmed/22595392 

A 50-year-old woman presented to the hospital after 4 days of generalized muscle aches and dark urine. She admitted to consuming one and a half bags of black licorice bites containing 2% natural licorice during the past 3 weeks. Examination showed high blood pressure ...

A Case of Perioperative Hypokalemia and Hypertension due to Concomitant Use of Multiple Herbal Medicines. Tanaka T. Masui. 2015 Dec;64(12):1280-3. http://www.ncbi.nlm.nih.gov/pubmed/26790334

A 72-year-old woman underwent surgery for a distal radius fracture with lower jaw fracture under general anesthesia. Preoperative laboratory data showed hypokalemia, hypertension, and leg edema. The suspected cause of all of these symptoms was the licorice component of the multiple herbal medicines which she was taking ... 

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Our heart symptoms factsheet

Our salicylates factsheet

updated October 2023