Most commonly abused over-the-counter drugs

The availability of over-the-counter (OTC) medications offers the public a plethora of benefits—but this does have its drawbacks, including the potential for abuse and addiction.

Consider that US consumers make 26 trips annually to pharmacies and retail outlets to purchase OTC medicines—spending approximately $340 yearly—but only visit their physicians about three times a year. Due to their easier accessibility and general affordability compared with prescription drugs, OTC medications are often used to treat common medical conditions, and physicians often recommend OTC drugs to mitigate the high costs of healthcare.

Although generally safe when used at recommended doses, OTC medications can pose certain dangers to users, including adverse drug-drug interactions, exacerbation of health problems, and adverse effects secondary to active ingredients. Furthermore, OTC drugs, when misused, can lead to abuse and thus increase the risk of addiction.

The most commonly abused OTC drugs in the United States include sedative antihistamines, laxatives, and decongestants. Let’s take a look at several examples:

Dextromethorphan (DXM)

DXM is used for temporary relief of cough caused by the common cold. It is a non-opioid congener of levorphanol that is devoid of analgesic or addictive properties. DXM is used with antihistamines, decongestants and expectorants. Physicians should be on the lookout for abuse and misuse of this drug.

Individuals may swallow or mix DXM with soda for flavor in an abuse practice called “robo-tripping” or “skittling,” inject it, or mix it with other drugs such as marijuana or alcohol.

Examples: Delsym, Robitussin Cough, and Vicks 44.

General adverse effects: Confusion, excitement, irritability, nervousness, and serotonin syndrome (rare).

Contraindicated in: Patients on monoamine oxidase inhibitors (MAOIs).

Maximum dosage: 120 mg/d by mouth for extended- and immediate-release formulations when used as a cough suppressant.

Overdose antidote: According to the National Institute on Drug Abuse, there are currently no FDA-approved medications to treat DXM addiction, and emergency medical attention should be administered in the event of an overdose. In twocase studies, naloxone was used to counteract DXM poisoning.

Loperamide

Loperamide is a synthetic opioid that is taken to relieve diarrhea. When taken in large enough doses, loperamide can result in a euphoric effect.

Example: Imodium A-D.

General adverse effects: Abdominal pain, constipation, nausea, drowsiness, dizziness, and dry mouth.

Contraindicated in: Children aged ≤ 12 years and patients with bloody or black stools.

Maximum dosage: 16 mg/d by mouth for loperamide hydrochloride (adults and teenagers)

Overdose antidote: In the event of an overdose, administer naloxone to reverse respiratory or significant central nervous system (CNS) depression.

Pseudoephedrine/phenylephrine

Decongestants containing pseudoephedrine or phenylephrine are used for the temporary relief of sinus congestion and pressure due to the common cold, hay fever, or allergies.

The sale of decongestants containing pseudoephedrine is now “behind-the-counter,” with pharmacies selling these drugs in limited quantities and requiring photo identification, because they can be diverted to make methamphetamine (crystal meth).

Examples: Sudafed (with pseudoephedrine) and Sudafed PE (with phenylephrine).

General adverse effects: Anxiety, arrhythmias, tachycardia, high blood pressure, headache, dizziness, tremor, and insomnia.

Contraindicated in: Patients taking MAOIs. Use with caution in patients with heart disease, high blood pressure, diabetes, thyroid disease, and benign prostatic hypertrophy.

Maximum dosage: Varies by formulation

Overdose antidote: Benzodiazepines for agitation/seizures for pseudoephedrine; no antidote for phenylephrine.

Diphenhydramine (DPH)

DPH acts on peripheral and central histamine H₁ receptors, thereby reducing allergic symptoms and resulting in sedation, respectively. It is also used in sleep aids.

DPH is a potent competitive antagonist of muscarinic acetylcholine receptors, and can thus potentially cause sinus tachycardia, dry mouth, mydriasis, blurred vision, ileus, urinary retention, CNS depression, agitation, hyperactivity, or psychosis. Because DPH has a number of effects, it is used for a variety of medical conditions—opening the door to abuse and misuse. It is abused for behavioral effects, such as elevated mood, a jolt to energy levels, and limited euphoria.

Example: Benadryl Allergy, Nytol, and Sominex.

General adverse effects: Drowsiness, dizziness, fatigue, nausea, and urinary retention.

Contraindicated in: Children aged < 2 years (Benadryl), children aged < 12 years (Nytol, Sominex), and in combination with other sedatives and alcohol. Users should exhibit caution when driving or operating machinery.

Maximum dosage: Varies by formulation.

Overdose antidote: Physostigmine is used to treat diphenhydramine toxicity.

Acetaminophen

When it comes to the relief of minor aches and pains—most notably headaches—acetaminophen is a godsend. But many people abuse or misuse this medication, which puts approximately 60,000 Americans in the hospital each year.

Acetaminophen overdose can result in liver failure, and chronic overuse of this OTC drug can result in increased liver enzyme levels, liver damage, and toxic hepatitis. Physicians should keep in mind that a wide range of products contain acetaminophen, which can result in unintentional overdose.

Example: Tylenol.

General adverse effects: Drowsiness, hepatotoxicity (related to dose), nephrotoxicity (with chronic overdose), and hypersensitivity reactions (uncommon).

Contraindicated in: Patients taking other drugs containing acetaminophen, and patients drinking ≥ 3 or more alcoholic beverages per day.

Maximum dosage: 3,000 mg/d by mouth; under medical supervision, up to 4,000 mg/d.

Overdose antidote: N-acetylcysteine

Oxybutynin transdermal system

Although OTC, this drug should only be used after consulting with a physician. Oxybutynin is used in the treatment of overactive bladder in women with symptoms of urge incontinence and urinary urgency/frequency lasting ≥ 3 months. When abused, this anticholinergic drug can result in fewer depressive symptoms, euphoric effect, and relaxation.

Example: Oxytrol (for women) and Ditropan XL.

General adverse effects: Sleepiness, dizziness, confusion, dry mouth, constipation, and blurred vision.

Contraindicated in: Females aged < 18 years, those with urinary tract infections, and patients with unexplained lower back pain.

Maximum dosage: 20 mg/d by mouth for immediate-release; 30 mg/d by mouth for extended-release Ditropan XL.

Overdose antidote: Physostigmine is indicated to reverse CNS effects caused by clinical or toxic dosages.

Antacids

Antacids are used to calm upset stomach with heartburn, acid indigestion, and sour stomach. Products containing simethicone—such as Maalox and Mylanta—help with bloating, pressure, or gas symptoms.

Antacids, however, can lead to “acid rebound” with long-term use. Acid rebound refers to a paradoxical acid hypersecretory state associated with heightened gastrin levels. Antacids can also significantly interfere with the absorption of various prescription drugs. Furthermore, in 2016, the FDA issued a statement warning consumers about the increased risk of serious bleeding when using OTC aspirin-containing antacid products.

Examples: Alka-Seltzer Heartburn, Tums, Maalox, Mylanta, milk of magnesia, and aluminum hydroxide (generic).

General adverse effects: Diarrhea (magnesium preparations) and constipation (aluminum preparations).

Contraindicated in: Patients with severe renal impairment (aluminum- and sodium-containing products), and patients with heart failure or hypertension (sodium-containing products).

Maximum dosage: Varies by formulation.

Overdose antidote: Antacids are generally safe but can lead to a buildup of aluminum in people with kidney failure, leading to aluminum toxicity. Excess use of certain calcium-containing antacids can also lead to alkalosis. In the event of severe toxicity, seek emergency medical attention.

Other regularly abused OTC products

In addition to the aforementioned drugs, there are several other OTC, non-medication products with known abuse potential, including paint thinners, glues, correction fluids, and aerosol sprays. These items should also be considered by physicians when sussing out a medical history of abuse or misuse.

When in doubt about OTC overdose or abuse, contact American Association of Poison Control Centers at 1-800-222-1222. They offer free, 24-hour professional advice from pharmacists, nurses, and toxicology specialists, and physicians.