Research shows, consuming too much of these can be lethal

By Naveed Saleh, MD, MS
Published October 26, 2020

Key Takeaways

We all know moderation is important when it comes to what we eat and drink. But you might be surprised to find out that “too much of a good thing” can actually mean toxic, or even lethal, when it comes to certain foods and beverages we commonly consume.

Whether it’s something we ingest every day—like water—to common pantry items and even a popular candy you might have around this Halloween, too much of these items can be harmful to your health. 

Black licorice

Halloween is just days away, and for many people—young and old alike—it’s a time for consuming copious amounts of candy. One popular treat, however, comes with an FDA warning to eat in moderation only, and that’s black licorice.

The FDA cautions candy consumers of any age to avoid ingesting large amounts of black licorice. However, in people aged 40 or older, consuming 2 or more ounces of black licorice per day for at least 2 weeks can lead to irregular heart rhythm or arrhythmia—and might even land you in the hospital. 

Licorice is a low-growing shrub cultivated in Greece, Turkey, and Asia that’s been used throughout history as a traditional remedy in the East and West for heartburn, stomach ulcers, sore throat, and infections, among other maladies. Black licorice contains a root-derived sweetening compound called glycyrrhizin, which can cause hypokalemia. Licorice poisoning can also cause hypertension, lethargy, edema, and congestive heart failure. Black licorice was even in the news this fall when a 54-year-old man died of a heart attack after eating excessive amounts of it—a bag and a half every day over a few weeks.

Moreover, black licorice can interact with certain medications, herbs, and supplements. Individuals who have pre-existing conditions, such as high blood pressure, congestive heart failure, kidney disease, or low potassium levels, should avoid glycyrrhizin-containing licorice products altogether, according to Healthline

The good news is that many licorice products made in the US do not actually contain real licorice, but instead use anise oil, which has a similar taste and smell. Checking ingredient labels can help discern whether real licorice is being used.


Derived from the bark of the Cinnamomum species of plant, this spice not only has a rich culinary history but has also long been used as a folk medicine to treat heart failure, influenza, anorexia, psychiatric problems, and more. Recent evidence points to its clinical benefit in Alzheimer disease, atherosclerosis, arthritis, and diabetes. Cinnamon is also a laxative and antiseptic.

Too much cinnamon, however, can be lethal. Based on data extrapolated from rat studies, consuming more than 6 grams of cinnamon, or about 1.5 teaspoons, in a 165-pound person could be deadly. Specifically, cinnamon contains coumarin, which in high quantities can cause harmful anticoagulation and hepatotoxicity. So, go ahead and use cinnamon in your gingerbread batter this holiday season, just don’t go overboard. 


Intriguingly, nutmeg can make for a low-cost drug of misuse, and lead to euphoria and hallucinogenic effects. Experts posit this is why nutmeg may have been added to eggnog—for an extra bit of holiday cheer. (Be warned, add too much nutmeg and cinnamon to the eggnog, and you may be in for one doozy of an emergency room visit.) Indeed, mixing nutmeg with alcohol or marijuana is known to potentiate euphoric effects. But consuming 2 to 3 teaspoons of the spice could even be lethal. 

The active substance in nutmeg is myristicin, a volatile-oil admixture containing allylbenzene derivatives and terpenes. Myristicin exerts weak monoamine oxidase inhibitor actions and can be metabolized into an amphetamine-like compound with hallucinogenic effects akin to LSD. Other molecules found in myristicin are serotonergic in nature and could lead to cardiovascular responses.

Symptoms of nutmeg toxicity usually involve the central nervous system, such as anxiety, psychosis, and a feeling of impending doom, as well as the cardiovascular system, including tachycardia and palpitations. Other symptoms include flushing, dry mouth, unsteadiness, nausea, epigastric pain, urinary retention, and blurred vision. Anxiolytic symptoms are likely due to the serotonergic and GABAergic properties of nutmeg.

According to the authors of a case report published in the BMJ concerning an 18-year-old woman who presented in a trance-like state after ingesting a large amount of nutmeg, nutmeg toxicity is likely under-recognized among healthcare providers.

They wrote, “Although the risks of nutmeg intoxication after voluntary use are not unknown to the medical community, certain groups of the population are still likely to experiment for low cost recreational drug alternatives. The presentation of acute psychotic symptoms accompanied by central nervous system neuromodulatory signs should alert the physician to this rare but probably underreported possibility especially in urban areas known to attract recreational substance users.”


With water, there can definitely be too much of a good thing. In a tragic and misguided accident, a 28-year-old woman died after drinking 6 liters of water in a span of 3 hours as part of a radio-station contest.

According to the authors of a case study published in the Journal of Clinical Pathology, “Water intoxication can occur in a variety of different clinical settings but is generally not well recognised in the medical literature. The condition may go unrecognized in the early stages when the patient may have symptoms of confusion, disorientation, nausea, and vomiting, but also changes in mental state and psychotic symptoms. Early detection is crucial to prevent severe hyponatraemia, which can lead to seizures, coma, and death,” they wrote.

Symptoms of water intoxication usually manifest when sodium concentrations drop below 110 mmol/liter, with severe symptoms occurring at 90-105 mmol/liter. Acute dilutional hyponatremia causes water to rush into brain cells, and neurological symptoms progress from confusion to drowsiness to coma. Drinking copious volumes of water quickly can be particularly dangerous.

Populations at risk for water intoxication include military recruits who drink too much water in an effort to rehydrate after heat-related injury. Additionally, water intoxication can reflect psychiatric illness, with psychogenic polydipsia, or compulsive water drinking, predisposing to poisoning. Water intoxication can present as psychosis, with delusions, hallucinations, and confusion all par for the course.


Sodium is found in table salt, rock salt, soy sauce, and more. Although humans need salt to survive, too much of it can be fatal. A systematic review of fatalities related to acute ingestion of salt, published in Nutrients journal, found the lethal dose was estimated to be less than 25 g, or 4 tablespoons of salt, for an adult. 

Reported cases of salt toxicity include a man with developmental delays eating a load of salt intended as mouthwash, infants poisoned when salt was mistaken for sugar in formula, a child with pica and propensity for rock salt, a woman with dementia consuming from a bedside salt shaker, and a young man drinking soy sauce on a dare.

Poison Control paints a clear picture of the effects of too much salt. “Too much sodium can cause dangerous, even fatal effects. When there's too much sodium in the bloodstream, water rushes out of our cells to dilute it. That's damaging to most cells; it's devastating to brain cells. As they shrink, they're torn away from their usual locations. Torn blood vessels and fluid build-up in the brain cause seizures and coma. Fluid can build up in the lungs, causing trouble breathing. Other symptoms include intense thirst, nausea, vomiting, and weakness. Kidney damage also occurs,” the agency writes.

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