Unfortunately, tasty cough drops can be dangerous
You’ve had a cough for three days and you’re sucking on cough drops one after another, wondering — is that too many? Overdosing on cough drops sounds like a joke, but toxicologists take the matter seriously. The main ingredient in cough drops is often menthol, which in high doses can cause nausea, dizziness, and even seizures. Does this mean you should ditch the lozenges entirely and simply rely on other remedies during a cold?
How Menthol Relieves a Cough
Menthol is an organic compound derived from peppermint or eucalyptus oil. In moderate doses, it creates a cooling sensation and mild numbness in the throat. That’s exactly the effect we value in cough drops when our throat is scratchy during a cold.
But menthol has a flip side. When consumed in excess, the same substance causes irritation of the mucous membranes instead of soothing them. Imagine a moisturizing cream — a small amount softens the skin, but if you squeeze half a tube onto your face, you’ll only get irritation.
A new study showed that using cough drops is statistically associated with a longer-lasting cough. Researchers found significant correlations between cough severity and the average menthol dose per lozenge, the number of lozenges per day, and the total daily menthol dose. However, the authors cautiously note that cough severity may be linked to the amount of menthol consumed. But these are preliminary findings, not a final verdict.
Symptoms of Cough Drop Overdose
Dangerous cough drop overdoses are extremely rare. But that doesn’t mean overeating lozenges goes unnoticed. If you eat too many, the first symptoms will involve the gastrointestinal tract — nausea and vomiting due to irritation of the stomach lining. This is essentially your body’s signal that it’s time to stop sucking on candy.
If you ignore that signal and continue, the situation can become more serious. In high doses, menthol can disrupt nerve impulse transmission, leading to neurological symptoms such as confusion, drowsiness, dizziness, and in the most severe cases — seizures.
Symptoms escalate gradually, and reaching severe consequences is very difficult because the body usually fights back long before the critical threshold.
Dangerous Dose of Menthol for Health
A typical cough drop contains 5 to 10 mg of menthol. Toxicologists estimate the lethal dose of menthol at 50–150 mg per kilogram of body weight, although some calculations suggest a figure as high as 1,000 mg per kilogram.
Let’s translate this into understandable numbers. An adult weighing about 77 kg (170 lbs) would have to eat 400 high-menthol cough drops in one sitting just to reach even the lower end of the lethal dose. That’s the equivalent of at least 13 full packs, since a standard package usually contains 20–30 drops.
In other words, accidentally overdosing on cough drops is virtually impossible. The danger of menthol lozenges for a healthy adult under normal use approaches zero.
Fatal cases of menthol poisoning are extremely rare. One of the only documented episodes involved a worker at a mint factory in India who died from seizures and kidney failure ten days after cleaning a container of mint oil. In other words, it involved intensive inhalation of concentrated vapors, not lozenges.
Another extreme case involved an 86-year-old man whom neighbors found unconscious. He was admitted to the hospital with weakness, muscle pain, disorientation, ulcers, and heartburn. It turned out he had been eating two packs of cough drops a day for twenty years. This was a case of chronic abuse, not a one-time binge.
To get a lethal dose of menthol, you’d have to eat the contents of more than a dozen packs
Benzocaine in Cold Lozenges
There is an ingredient that should be taken more seriously than menthol. Some cough drops contain benzocaine — a local anesthetic. And here the danger is more significant.
Benzocaine is found in lozenges less and less frequently today precisely because of the risk of overdose. It can cause methemoglobinemia — a condition in which hemoglobin loses its ability to carry oxygen. The body’s cells receive too little oxygen, lips and hands turn blue, and in severe cases, it can be life-threatening.
Methemoglobinemia occurs when the iron in hemoglobin changes from its ferrous (divalent) form to its ferric (trivalent) form. In this state, the hemoglobin molecule simply cannot capture oxygen. It’s like changing the lock on a door: the key is the same, but you can’t turn it.
Symptoms of methemoglobinemia usually appear within minutes or up to two hours after benzocaine use. Therefore, when buying cough drops, it’s worth checking the ingredients: if they contain only menthol, the risk of serious side effects is minimal when following the instructions.
What to Do in Case of Cough Drop Overdose
If you have any doubts, call the poison control hotline. In Russia, this function is performed by toxicology centers at major hospitals and the unified emergency number 112.
Practical rules to help avoid problems:
- Follow the instructions on the package — if you follow the manufacturer’s recommendations, you stay in the safe zone;
- Don’t give small children unsupervised access to cough drops;
- If you’re sick and know you’ll be sucking on lozenges all day, set aside in advance the number indicated on the pack as the allowable amount — this way you won’t exceed the safe dose;
- Check the ingredients, and avoid lozenges containing benzocaine unless specifically prescribed by a doctor.
Cough drops should be stored out of children’s reach
It’s also worth monitoring whether your cough is dragging on. Researchers suggest that if you have a prolonged cough, try stopping menthol lozenges, as they may actually be hindering recovery.
Cough drops are not candy, even though they look and taste very similar. Under normal use, they are safe and genuinely help you get through the unpleasant days of a cold. But mindlessly going through pack after pack is not advisable — menthol in large quantities irritates the mucous membranes, and chronic overuse can lead to serious consequences. The best advice is to read the instructions on the package and follow them, and if your cough doesn’t go away after more than a week, see a doctor rather than reaching for another lozenge.
The study results were published in the scientific journal Wisconsin Research and Education Network.
