A tea called Throat Coat made me lethargic and I was found to have low potassium. Is this a known problem? I was drinking 5 cups a day.

Answer:

The problem is with licorice root in Throat Coat tea, and this can also be a problem with black licorice candy and other licorice-containing foods.

Throat Coat contains a very large amount of licorice root (760 mg per tea bag) plus another 60 mg of a 6:1 licorice root extract, and these ingredients are likely to be the cause of your issues. Licorice root provides great sweetness and flavor, but you need to exercise caution and moderation with it because it contains glycyrrhizin (or glycyrrhizic acid). Through an effect on the kidneys, glycyrrhizin in licorice root can cause loss of potassium, fluid retention, increased blood pressure, abnormal heart rhythms, and lethargy. Throat Coat has a warning on its box regarding these issues, although the warning does not identify the causative agent — licorice root.

Experts recommend limiting intake of glycyrrhizin to 100 mg/day for most adults, although this limit may be too high for people with high blood pressure, slower digestion (causing increased absorption), or electrolyte-related or water homeostasis-related medical conditions, such as kidney disease and Cushing's syndrome (European Scientific Committee of Food, 2003).

In late 2025, ConsumerLab tested another licorice tea from Traditional Medicinals (the same company that distributes Throat Coat) and found it to contain even more glycyrrhizic acid per brewed cup than a serving of black licorice candy or even licorice root supplements. Consuming more than two cups per day would exceed the 100 mg limit. See our Licorice and DGL Supplements, Candies, and Tea Review for tests of related products. ConsumerLab is currently testing Throat Coat and will post findings in early 2026.

A study of 33 brands of licorice tea found that a 250-mL (about 8-oz) cup of tea contained anywhere from just 0.5 mg to 112.5 mg of glycyrrhizic acid, or 31.5 mg on average (Allcock, BMJ Case Reports 2015).

There have been many examples of people experiencing problems with licorice tea. A woman in New York who was drinking five to six cups per day of a licorice tea that fit the description of Throat Coat was found, on routine testing, to have a blood level of potassium of just 2 mEq/L (normal range: 3.5 to 5.3 mEq/L) (Saha, Cureus 2025). An 84-year-old man (with hypertension controlled by medication) developed extremely high blood pressure, headache, photophobia, chest pain (due to pulmonary edema) and fatigue, as well as low potassium after two weeks of drinking 1 to 2 glasses daily of homemade licorice root extract called "erk sous" (Falet, CMAJ 2019). A 57-year old man in Turkey with no prior history of cardiovascular disease experienced atrial fibrillation (a rapid, irregular heartbeat) likely caused by low potassium levels after consuming four glasses of "licorice root syrup" daily for one month (Erkus, Turk Kardiyol Dern Ars 2016). Although testing by a separate research group identified heavy metals in a certain Throat Coat tea product, in our opinion, the amounts are not a significant concern. Sign in as a member to find out why.

Licorice Candy

The FDA has warned that, if you're 40 or older, eating 2 ounces of black licorice a day for at least two weeks can cause similar problems, although younger people can also be affected. A study among healthy young adults (average age 24) showed that eating 3.3 grams (about 0.1 oz) of licorice candy containing 100 mg of glycyrrhizin (as measured by the researchers) daily for 2 weeks increased systolic blood pressure by about 3 mmHg compared to placebo, with statistically significant increase of 1.7 mmHg observed as early as five days after starting licorice intake. Interesting, it was found that the amount of glycyrrhizin in the licorice studied was 50% higher than declared on the label, indicating that labels may not be accurate. (Note: In the U.S., manufacturers are not required to list the amount of glycyrrhizin in black licorice, although the FDA states that soft candies can contain no more than 3.1% on a weight basis — FDA, 9/26/2023) (Geijerstam, Am J Clin Nutr 2024).

In extreme cases, excessive intake of glycyrrhizin from candy can cause death. For example, a 54-year-old man went into cardiac arrest and died after consuming one to two large packages of licorice-flavored soft candy for three weeks. His doctors determined that the glycyrrhizic acid in the candy likely led to low potassium levels and other metabolic changes that resulted in a rapid, abnormal heart rhythm (Edelman, New Eng J Med 2020).

In Europe, but not in the U.S., a warning label stating "Contains liquorice — people suffering from hypertension should avoid excessive consumption" is required on licorice-containing candies and beverages if they contain excessive concentrations of glycyrrhizin. Nevertheless, an analysis of 219 candies, ice creams, and brewed teas in Denmark found that 10% of all samples did not properly include the required label warning. Those that exceeded limits tended to contain pure licorice, with pure licorice candies, for example, containing 18 times as much glycyrrhizin as other candies. Among high-glycyrrhizin products, eating just 0.15 ounces (4.3 grams) of the candy or 2 ounces (59 grams) of the ice cream, or drinking just 2.8 fl oz (83 mL) of the tea, would exceed the recommended limit of 100 mg/day of glycyrrhizin (Ballin, Food Control 2022).

ConsumerLab tested two licorice candies in 2025 (Panda and Wiley Wallaby) and found substantial amounts of glycyrrhizic acid, with one product containing more than twice as much glycyrrhizic acid as the other per equal serving.

Licorice Supplements

Be aware that most licorice root supplements in the U.S. do not list the amount of glycyrrhizic acid they contain, but only list the amount of licorice root powder or extract. Even deglycyrrhizinated licorice (DGL) products (those from which some of the glycyrrhizin has been removed) can contain significantly more glycyrrhizin than expected, as ConsumerLab reported in its Licorice and DGL Supplements, Candies, and Tea Review.

Reports of adverse effects from consuming licorice root supplements include a 68-year-old Chinese-American woman who developed dangerously high blood pressure (219/123 mm Hg), resulting in a stroke (with symptoms including difficulty speaking and paralysis on one side of the body) after taking Chinese herbal supplement pills providing 800 mg of licorice root daily for two weeks to treat indigestion. The supplement contained several other ingredients, such as ginger root and cinnamon bark, but the reporting physicians noted the woman could have been consuming 8 times the maximum dose recommended by the European Commission Scientific Committee on Food of glycyrrhizin (Shin, Neurohospitalist 2019). In another case, a 65-year-old woman developed high blood pressure (197/89 mmHg), low potassium levels and high sodium levels, metabolic alkalosis, as well as adrenergic symptoms (agitation, anxiety, and tremor – which, together with high blood pressure and low potassium levels, indicate acquired mineralocorticoid excess (AME) syndrome), four months after she began taking four capsules daily (the recommended daily serving) of Advanced Liver Support (Advanced BioNutritionals), which contains 1,000 mg of dried licorice root extract standardized to contain at least 200 mg of glycyrrhizic acid (twice the recommended daily limit for consumption glycyrrhizin in Europe, as discussed above), along with other ingredients including selenium, phosphatidylcholine, and milk thistle. Her symptoms resolved and her blood pressure -- as well as potassium and sodium levels -- returned to within normal ranges two weeks after she received treatment and stopped taking the supplement (Szendrey, J Med Case Rep 2024).