When most people imagine drugs of abuse, they think of legal but dangerous substances like alcohol and tobacco, or they might think of illegal drugs like heroin, cocaine, meth, or marijuana. Although these are commonly abused substances, which can become addictive and have dangerous side effects, they are not the only intoxicating substances available. Prescription drug abuse is on the rise in the United States, and as more regulators crack down on this problem, people who struggle with addiction or substance abuse are turning to over-the-counter substances.

There are many substances that are available over the counter, which can, in large enough doses, cause intoxication, a euphoric high, or hallucinations. Despite their widespread availability, it is very dangerous to abuse these substances due to combinations of active ingredients or the potential to overdose quickly.

Here are five of the most commonly abused over-the-counter drugs:

  1. Dexomethorphan (DXM)

This substance is the main active cough-suppressing ingredient in over-the-counter medicines like Robitussin. The drug can either be found alone as the active ingredient or in combination with other active ingredients like acetaminophen (Tylenol), antihistamines, decongestants (pseudoephedrine, Nyquil), or expectorants (guaifenesin). When ingested at regular doses of 15-30 mg, taken 3-4 times per day for the duration of symptoms, the effects of DXM on suppressing cough can last for 5-6 hours.

Although some states are taking steps to regulate who can purchase over-the-counter medicines containing DXM and in what quantities, the drug is still legal for manufacture, sale, and ingestion in the US. However, the Drug Enforcement Administration (DEA) lists this as one of its “Drugs of Concern” due to its potential for addiction and abuse.

When DXM is abused in large doses, the individual can experience euphoria and hallucinations, typically visual and auditory. Nonmedical doses of DXM range from 250 mg to 1,500 mg. Originally, DXM was found primarily in liquid cough syrups, but now it has been added in larger doses to gel capsules, which are becoming the primary method of abuse. Symptoms of intoxication on DXM include lethargy, overexcitement, hypertension or high blood pressure, slurred speech as though drunk, sweating, and involuntary twitching or spasms of the eyes. Side effects and dangers of abusing DXM include nausea, vomiting, dehydration, loss of coordination, liver damage, seizures, and coma.

cough syrup
  1. Pseudoephedrine

This drug is an active ingredient in many allergy, sinus, cold, and flu medicines, because it reduces the size of the blood vessels in the nose, preventing “stuffiness.” It relieves the symptoms of sinus congestion, and in over-the-counter doses, it is typically safe to ingest. Some individuals abuse pseudoephedrine at higher doses because of the medication’s mild stimulant effects; however, this substance is primarily regulated due to its role in illicit domestic methamphetamine manufacturing.

While there are attempts to regulate or criminalize the manufacture of products containing pseudoephedrine as far back as 1986, over-the-counter pharmaceutical manufacturers managed to successfully combat this concern. Instead, the primary piece of legislation that regulates the manufacture, sale, and consumption of pseudoephedrine products is the Combat Methamphetamine Epidemic Act of 2005. As pseudoephedrine products became more difficult to purchase, the purity of meth dropped, and fewer people entered rehabilitation programs for treatment of meth abuse or addiction, which indicates that the number of people struggling with meth addiction has also dropped.

Some pharmaceutical companies are pursuing decongestants using pseudoephedrine that should be more difficult to illicitly manufacture into methamphetamines. However, the DEA does not recognize these substances as foolproof, and pseudoephedrine remains highly regulated.

  1. Imodium

This brand-name medication is generically called loperamide, and it has an active ingredient that helps to slow the movement of the bowel to reduce or prevent diarrhea. It is an over-the-counter medication, and it should not be used to treat this problem on a long-term basis. The active ingredient in loperamide is a mild opioid, which is a small enough dose to bind to opioid receptors in the stomach and intestines, but it should not cross the blood-brain barrier in standard doses.

However, as the opioid addiction epidemic continues across the US, narcotic painkillers are becoming less frequently prescribed and harder to access. For people who struggle with opioid addiction, high doses of Imodium can, allegedly, ease withdrawal symptoms, especially the diarrhea and nausea associated with the body ending its dependence on narcotics. Imodium is also increasingly becoming a substance of abuse. People take very large doses of the medication in order to force the opioid to “rush” the blood-brain barrier by overloading the bloodstream with the drug. This can rapidly lead to overdose and other health problems.

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  1. Dimenhydrinate

This chemical is an antiemetic, and it is the main active ingredient in medications like Dramamine, a medication to prevent motion sickness. It is a histamine receptor agonist, and in over-the-counter medications, it can produce a sense of calmness and mild euphoria. However, when people abuse dimenhydrinate in nonmedical doses, it induces intense euphoric sensations, or a high, and can also cause hallucinations.

Side effects of dimenhydrinate intoxication include flushed face and skin, large pupils, sleepiness or drowsiness, hyperactivity, hallucinations, confusion, seizures, coma, and difficulty speaking, swallowing, or standing.

  1. Diphenhydramine

This is an antihistamine drug primarily found in medicines like Benadryl, used to treat allergies that inflame the sinuses. Sometimes, this medicine can be used as a sleep-inducing drug. Since it is not highly regulated, like DXM or pseudoephedrine, this substance can be abused in large quantities, especially by teenagers or incarcerated individuals, to induce a euphoric high and potentially hallucinations. Diphenhydramine tends to be sought out for abuse in communities that do not have access to other intoxicating substances.

Side effects of diphenhydramine abuse can include drowsiness, heart palpitations, dizziness or loss of coordination, flushed skin and face, nausea and vomiting, anxiety or restlessness, abdominal pain, inability to urinate, dehydration, tremors, seizures, delirium, coma, and death.

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The nonmedical use of any medicine is dangerous. With over-the-counter medications, the amount of active ingredients is low, so it takes a large amount of any substance to induce any kind of intoxication. This can lead to organ damage, psychological problems, and overdose. Still, some substances available over the counter can be addictive or abused as part of a problem with polydrug abuse, or co-occurring mental health and substance use disorders.