A plant root, black licorice has been touted as a remedy for everything from digestive system ailments to sore throats and bronchitis, to osteoarthritis and malaria. When eaten in large quantities, however, black licorice can be lethal.
Too much of a good thing
The US Food and Drug Administration (FDA) has issued a warning cautioning people 40 and over against eating more than 2 ounces of black licorice a day for two weeks or more. FDA experts say that black licorice contains the sweetening compound glycyrrhizin, which can lower potassium levels in the body and lead to abnormal heart rhythms, high blood pressure, edema, lethargy and congestive heart failure.
The National Institutes of Health (NIH) has also weighed in on the licorice issue, reporting other possible side effects from eating too much black licorice, including “paralysis and occasionally brain damage in otherwise healthy people.” According to the NIH, as little as 5 grams of black licorice a day can cause serious problems in people who eat a lot of salt or who have heart disease, kidney disease or high blood pressure. In addition, bingeing on licorice can cause headaches, water and sodium retention, hormone imbalance and sexual dysfunction.
NIH precautions and warnings
The NIH cautions against overindulging in black licorice if:
- You are pregnant and breast-feeding. The NIH warns that eating licorice while you are pregnant could cause a miscarriage or early delivery. Because not enough is known about the safety of eating licorice while breast-feeding, the NIH advises against it.
- You have high blood pressure. Black licorice can raise your blood pressure; don’t consume it if yours is already high.
- You have heart disease. Licorice can cause the body to retain water and this can worsen congestive heart failure. Excessive licorice intake can also cause an irregular heartbeat.
- You have a hormone-sensitive condition, including breast, uterine or ovarian cancer; endometriosis or uterine fibroids. Licorice may act like estrogen in the body and should be avoided if you have a condition that can be made worse by this hormone.
- You have hypertonia. Licorice’s potassium-lowering side effect makes this muscle condition worse.
- You have low levels of potassium in your blood. Licorice can make your already depleted potassium plummet to dangerous levels.
- You are experiencing problems with sexual dysfunction. Ingesting large amounts of licorice can lower testosterone levels, decreasing a man’s interest in sex and worsening erectile dysfunction.
- You have kidney disease. Eating too much black licorice could make your condition worse.
- You are going to have surgery. Licorice can interfere with blood pressure control before and after surgery. The NIH advises you stop your licorice intake at least two weeks before surgery.
Drug interactions
Black licorice is known to interact with some medications. In particular, the NIH warns against eating licorice while taking warafin (Coumadin). When this anti-blood clotting drug is combined with black licorice, its effectiveness decreases and the possibility of a clot forming increases. Licorice’s properties also mean it can interfere with digoxin, estrogens, furosemide, blood-pressure drugs, steroids, diuretics, and some medications that are broken down by the liver, including phenobarbital, Celebrex, ibuprofen and tamoxifen.
It must be noted that these side effects result when “real” black licorice is ingested. Licorice-flavored products containing anise do not pose these threats. If you have been eating large amounts of natural black licorice and have experienced any of the symptoms covered here, the FDA urges you to contact your physician.
