Key Points

  • Cough suppressant drops contain the active ingredient dextromethorphan.
  • Some cough lozenges help to break up mucus in the lungs.
  • It is difficult to overdose on menthol cough drops alone.
  • Some cough drops contain herbal supplements and vitamins touted to boost the immune system.
  • Although overdosing on cough drops is difficult, one should never take more than directed.

Cough drops are a safe and effective way to treat a sore throat and cough caused by dry mouth, allergies, colds, or flu.[1] Many cough drops contain ingredients that soothe the throat and boost the immune system. However, most contain active ingredients that quiet chronic coughing and expel trapped mucus in the lungs. 

Individuals troubled by persistent coughs may be tempted to use more than the recommended amount on the package. However, using too many cough drops can cause a laxative effect and side effects such as nausea or bloating. In some cases, it can even cause an overdose.[1]

Although it is possible to overdose on cough drops, it is an extremely rare occurrence.

Types of Cough Drops

There are three types of cough drops available over the counter. Each has its own mechanism of action and benefit. 

They include:

  • Cough suppressants: The most commonly used cough drops are cough suppressants. These drops contain dextromethorphan, a central nervous system cough suppressant that helps quiet the cough.[2] Some may also contain the local anesthetic benzocaine to numb a sore throat or intermittent throat pain.
  • Expectorants: The next most commonly used cough drops are expectorants.[3] They are designed to loosen lung mucus and improve nasal congestion, making coughing easier. Individuals with dry coughs most commonly use expectorant drops. 
  • Herbal: Herbal cough drops are not regulated by the U.S. Food and Drug Administration (FDA) due to their inclusion of herbal ingredients such as peppermint and eucalyptus.[4] Therefore, they are not medically proven to work as cough suppressants or expectorants. However, there may be studies to support their efficacy. 

Some cough drops may also include vitamin C, zinc, or other substances that support the immune system. 

How Many Cough Drops Does it Take to Cause an Overdose?

How many cough drops it takes to cause an overdose depends on the active ingredient and dose. As a rule of thumb, following the manufacturer’s label for safe usage is always best. Anything beyond their recommendation could put you at risk of taking a lethal dose of menthol or dextromethorphan. 

Menthol Drops 

Menthol-based cough drops generally contain between 5 and 10 mg of menthol per drop.[5] According to the National Library of Medicine, it takes a large amount of up to 1,000 mg of menthol per kg of body weight to cause a fatal overdose.[6] However, ingesting the amount of cough drops to reach this limit would be extremely difficult. For this reason, there isn’t a set standard limit. 

Dextromethorphan

Dextromethorphan-based cough drops contain approximately 5.8 mg per drop.[1] It takes approximately 350 mg to 1000 mg to cause side effects similar to those of phencyclidine, but it can take 1500 mg to induce psychosis, hallucinations, and paranoia.[7] Anything beyond the dose can lead to an overdose. 

Signs of Cough Drop Overdose

The signs of a cough drop overdose depend on the active ingredient: dextromethorphan or menthol.

Signs of Dextromethorphan Toxicity

man taking a cough drop

Signs of dextromethorphan toxicity include:[8]

  • Dilated pupils
  • Mild agitation 
  • Psychosis
  • Muscular rigidity 
  • Hyperthermia
  • Altered mental status
  • Difficulty breathing
  • Confusion
  • Hallucination
  • Fast heartbeat 
  • High blood pressure
  • Seizure
  • Coma

Anyone suspected of a dextromethorphan overdose should be treated in the emergency room right away. 

Signs of Menthol Toxicity

Taking pure menthol in high doses can lead to an overdose. However, the menthol in cough drops is heavily diluted. The amount of menthol it takes to suffer an overdose from a cough drop is, therefore, unknown.

Signs of menthol toxicity from undiluted menthol include:[5]

  • Blood in urine
  • Inability to urinate 
  • Rapid breathing
  • Shallow breathing
  • Abdominal pain
  • Diarrhea
  • Nausea
  • Vomiting
  • Rapid heartbeat
  • Heart palpitations
  • Convulsions
  • Dizziness
  • Tremor
  • Unconsciousness
  • Unsteady walking

Treatment for menthol overdose includes IV fluids, activated charcoal, laxatives, or medications to reverse the effects of menthol.[5]  

Risks of Overdosing on Cough Drops

One risk of overdosing on cough drops, especially those containing dextromethorphan, is mental health issues resulting from psychosis or hallucinations.[9][10]This includes developing post-traumatic stress disorder (PTSD), generalized anxiety disorder (GAD), or depression. Some people may struggle with significant health issues following a cough drop overdose, including liver or kidney damage. Many of these symptoms are reversible with prompt medical treatment. 

Can You Become Addicted to Cough Drops?

No. Cough drops do not carry the potential for addiction, and their ingredients do not appear in any federal substance schedule. Even when misused, it is impossible to become addicted to cough drops. However, it is possible to overdose on them or experience adverse effects from taking too many. 

Some people may like how they feel after taking cough drops with dextromethorphan, which may prompt them to go out and purchase the liquid version. Using too much of this drug or using it in a manner other than prescribed can lead to an overdose. 

According to the United States Drug Enforcement Administration (DEA),  dextromethorphan (DXM) is found in over 120 over-the-counter cold medications.[11] It is often abused for its ability to induce immense euphoria and a high similar to hallucinogens like ecstasy. Fortunately, DXM overdoses are treatable and rarely result in death. However, those that do result in death do so as a result of combining DXM with other drugs.