Medical News Today: How much menthol does it take to overdose?

Cough drops can be helpful for a sore throat or a nagging cough. In general, cough drops cannot cause an overdose and are safe to use. Their active ingredient, menthol, can result in an overdose in extremely high amounts, but these are hard to get from eating even large quantities of cough drops.

These candy-like lozenges can feel soothing and help calm a cough, at least temporarily. And if the symptoms are particularly severe, some people may eat a lot of cough drops.

Although it is difficult to overdose on them, there are some things to consider before using cough drops or consuming excessive amounts of them.

Menthol in cough drops
Cough drops on a wooden scoop on a board
Menthol is a common ingredient in cough drops, but it may be difficult to overdose on them.
Menthol is a component of peppermint oil that has a cooling effect.
It is a common ingredient in cough drops because it gives a temporary numbing effect that can relieve a sore throat or a cough.
Cough drops usually have 1 to 15 milligrams (mg) of menthol per drop.
The lethal dose is considered to be about 50 to 500 mg of menthol per kilogram (kg) of body weight.
This amount means someone who weighs 150 pounds would need to consume at least 340 to 3,400 cough drops, containing 10 mg of menthol each, to die from menthol poisoning.
They would also need to eat them in a relatively short span of time to risk toxic effects.
How many cough drops are too many?
There is no standard limit to how many cough drops can be consumed. This is because the amount of menthol and other ingredients varies between brands.
Cough drops should be treated as any medication, by following the information on the label to find out the safe dosage.
People who take other medications or who have other health conditions should also ask a doctor before taking cough drops or any new medications.
Symptoms of poisoning
Menthol is considered to be safe, and cases of poisoning are extremely rare. A few cases of menthol overdose have been cited in medical literature.
A study published in Case Reports in Medicine describes an 86-year-old man who was unconscious and taken to the emergency room. After regaining consciousness, doctors determined the person was experiencing:
sores in the mouth
skin lesions with a dry, yellow crust
muscle weakness
decreased kidney function
problems of thinking and mental function
Doctors discovered that the cause was eating 2 bags of menthol-rich cough drops daily for 20 years. Most of the symptoms went away after the individual stopped eating the cough drops and had physical therapy.
The International Journal of Applied and Basic Medical Research detailed one instance of fatal peppermint oil poisoning, but it was not from cough drops.
A 21-year-old died after inhaling high amounts of peppermint fumes, which contain menthol and other components. The cause was entering a peppermint oil tank to clean it. The fumes caused unconsciousness, a coma, and seizures. Death occurred after the person was hospitalized for 10 days.
There was no evidence of consuming peppermint or menthol but only the toxic effects of breathing unusually high amounts of peppermint fumes. Allergic reactions to menthol
Menthol can cause allergic reactions. These reactions can range from mild to severe.
Some people develop a reaction on the skin known as allergic contact dermatitis. A case reported in Contact Dermatitis discusses a 29-year-old who developed swollen, scaly lips from using toothpaste and throat medicine that contained menthol.
Another report in Contact Dermatitis describes two people who had allergic reactions from menthol-containing toothpaste. They experienced swelling and rashes around the mouth that went away after they stopped using the product.
Anaphylaxis, a severe allergic reaction, is possible with exposure to menthol. However, this extreme reaction is rare.
Menthol can be an irritant for people with sensitive skin. People should stop using cough drops and consult a doctor if itching, burning, or swelling occurs after eating them.
Other issues
Cough drops on a board. can you overdose on cough drops
Cough drops may be high in sugar.
Some cough drops contain as much sugar as candy. This level of sugar may not be safe for people with blood sugar problems and diabetes.
Other lozenges contain zinc, which is thought to help boost the immune system. But, taking too much zinc can cause side effects.
Cough drops sometimes contain vitamin C. This vitamin is important for many of the body's processes, including immune function and helping wounds heal.
As with any vitamin, it should not be taken in excess amounts without a doctor's approval.
People should read the cough drop label before taking them to be sure of what they are ingesting.

Cough drops may provide relief for a cold or allergies. They will not treat the underlying health problem, however. If the issue is a cold or other mild virus, the illness will run its course. The sore throat and cough should get better within a few days.
Sometimes, however, a cough or a sore throat is a sign of a more serious health issue. People should see a doctor if symptoms last more than a few days or get worse. A severe cough, constant coughing, or a cough that produces blood or green or yellow mucus should be checked immediately.