Substance Abuse of Legal Substances

Medically reviewed by:
Dr. Conor Sheehy, PharmD., BCPS

Table of Contents

What is Substance Use Disorder?

Substance use disorder is a medical condition used to describe the recurrent use of alcohol and drugs in a way that causes significant clinical and functional impairment. Substance use disorder is commonly associated with illicit drugs, but abuse and addiction can occur with legal substances such as alcohol, tobacco, and over-the-counter (OTC) medications, as well.

Addiction or SUD are interchangeable terms that refer to a chronic brain disease that requires long-term professional treatment to manage, similarly to other chronic conditions, like diabetes or asthma. A large part of addiction is dependence, which is when an individual becomes physically adapted to drug or alcohol use. They develop a tolerance to the substance’s effects, so that they require more to experience the same level of intoxication, and they suffer withdrawal symptoms when they decrease the dosage or quit.

In addition to tolerance and withdrawal, other signs and symptoms that a clinician may use to diagnose substance use disorder include:

  • Wanting to quit or cut down, but not being able to
  • Taking more of a substance more often than intended
  • Spending a great deal of time seeking out, using, and recovering from substance use
  • Intense cravings for the substance
  • Continuing to use despite suffering consequences from substance use
  • Failing to fulfill school, work, or personal obligations
  • Giving up social or recreational activities due to substance use
  • Acting in ways that are uncharacteristic and risky
  • Continuing to use despite suffering mental or physical problems either caused by or made worse by substance abuse

Types of Legal Substances Abused

What are legal substances that put people at a higher risk of developing an addiction? Below are the most commonly abused legal substances in the United States.

Alcohol Abuse

Alcohol is the most commonly abused legal substance, and it can have varying effects on different individuals. Clinicians recommend that men under 65 drink no more than two drinks per day and no more than 14 drinks a week. Women under 65 should limit themselves to one drink per day and no more than seven drinks per week. Excessive alcohol consumption, defined as more than three drinks in a single day, increases the chance of personal injury and long-term health problems.

One drink is equal to 10 milliliters (mL) of pure alcohol, which is the amount found in:

  • 12 ounces of beer
  • 8 ounces of malt liquor
  • 5 ounces of wine
  • 1.5 ounces 80 proof liquor
  • 1 ounce shot 100 proof liquor

On average, it takes the body one hour to metabolize a single drink. Tolerance varies with body weight, sex, age, recent food intake, the strength of the drink, and interactions with medications. Tolerance to alcohol’s effects can increase over time, and this is usually a sign of addiction.

Over-the-counter (OTC) Medicine Abuse

OTC medications can be just as dangerous and addictive as illicit drugs if they are used inappropriately. You may be abusing OTCs if you:

  • Take more than the recommended dose
  • Use it in a way other than directed
  • Take the drug for recreational reasons

The most commonly abused OTCs are cough and cold medicines containing dextromethorphan, which can produce a euphoric, intoxicating, and hallucinogenic effect in high doses.

Marijuana Abuse

Marijuana is a plant material that contains THC and other psychoactive substances that activate certain areas of the brain, causing euphoria, relaxation, heightened sensory perception, increased appetite, impaired body movement, altered sense of time, foggy thinking, and impaired memory. Marijuana can be inhaled by smoke or vapor, cooked into food, or mixed into drinks. An increasing number of states have legalized marijuana for recreational and medicinal use.

Tobacco Abuse

Tobacco contains nicotine, a highly addictive substance. People smoke, chew, or sniff tobacco. Nicotine stimulates receptors in the brain to release neurotransmitters in a way that produces alertness and a pleasant high in some people, while making others feel ill. Chronic tobacco users no longer feel a high from smoking, but they continue to use tobacco, because when they try to quit or cut down, they experience the symptoms of withdrawal such as irritability, increased appetite, tobacco cravings, and difficulty sleeping.

What are the Side Effects of Abusing Legal Substances?

Drug and alcohol addiction is a chronic relapsing disorder with genetic, environmental, and psychosocial components that influence its development and progression.

As an individual takes the drug over time, tolerance occurs as the desired effect diminishes. This leads many individuals to increase their intake of the substance, leading to an increase in the number and severity of   undesired side effects.


Common side effects of alcohol abuse are:

  • dangerous levels of intoxication
  • slurred speech
  • impaired judgement
  • risky behavior
  • memory problems
  • loss of coordination
  • sedation and unconsciousness

Chronic and/or excessive alcohol use can disrupt mood and behavior and cause more long-lasting issues with judgement, coordination, and behavior. It can cause cardiovascular problems such as high blood pressure, irregular heartbeat, and stroke, as well as serious problems with the liver, kidneys, and pancreas, and an increased risk of cancer.


Common side effects of dextromethorphan include:

  • heightened sensory experience
  • altered perception of time
  • visual hallucinations
  • nausea
  • vomiting
  • dizziness
  • hyperactivity
  • disorientation
  • panic attacks, seizures
  • heart irregularities
  • and dissociation from the physical body

Abusing dextromethorphan in combination with other drugs, such as MDMA or alcohol, creates a synergistic effect that intensifies the intoxicating, addictive, and dangerous impact of each substance involved. Many OTC formulations containing dextromethorphan also include other substances, such as acetaminophen or antihistamines that are hazardous in high doses, leading to consequences such as heart attack, liver damage, stroke, coma, and death.


Common side effects of tobacco use are coughing and a more sedentary lifestyle. Smoking long-term can lead to a variety of different cancers, chronic bronchitis, and emphysema, as well as cardiovascular problems that put smokers at significant risk of heart attack and stroke. Tobacco can reduce blood flow to the arms and legs and make the blood clot more easily, which can lead to pain, wounds that won’t heal, and death. Smoking can even impact sexual and reproductive health, increase arthritis risk, gum disease and tooth loss, premature aging, and conditions that lead to blindness.

What are the Signs of an Overdose?

Signs of alcohol overdose

Slurred speech, confusion, lack of coordination, changes in usual behavior, and the odor of alcohol are common signs of alcohol intoxication. The effects of a given amount of alcohol vary from person to person, depending upon how much alcohol the person consumes on a chronic or intermittent basis. When an intoxicated person becomes unconscious, is breathing too slowly or not deeply enough, or has no pulse, they are suffering from alcohol poisoning, a true medical emergency. Alcohol is involved in a very high proportion of drug overdose deaths.

Your response to a known or possible alcohol or alcohol plus other drug overdose should always be to call 911 and to follow the instructions provided by the 911 operator. You may need to perform rescue breathing or chest compressions. If the person is not awake and talking, do not attempt to “sober them up” by forcing coffee or other oral fluids into them.

Signs of prescription or OTC drug overdose

Although many people understand that illegal drugs can be very dangerous, prescription and OTC medications are involved in many overdoses. In general, signs of overdose tend to fall into either depressant or stimulant drug effects. Emergency symptoms and signs of depressant drugs (opioids, sedatives, muscle relaxers, etc.) include slow or inadequate breathing, low blood pressure, low heart rate, decreased level of consciousness, and even cardiac arrest. Stimulant drug (amphetamines, bath salts, synthetic marijuana, etc.) emergencies can include agitation, violence, confusion, very high blood pressure, very high pulse rate, very high body temperature, and possible heart failure leading to death. When a combination of medications and/or alcohol are involved, the signs may be mixed and not typical.

Any time an overdose is known or suspected, the first thing to do is to call 911 for emergency medical response. If necessary, the 911 operator will advise you how to assist the person until help arrives. This may include rescue breathing or chest compressions. If the person is violent, do not try to restrain them.

Signs of marijuana overdose

In general, traditionally smoked marijuana does not create emergency medical problems when used without other substances. Cannabis products with higher concentrations of tetrahydrocannabinol (THC), such as some e-vaping solutions, can result in severe overdose signs such as high blood pressure, high heart rate, unconsciousness, and vomiting that causes breathing problems. Marijuana is also commonly combined with other drugs and/or alcohol, so symptoms and signs of overdose are influenced by the other substances.

Cannabidiol (CBD) is another substance contained in marijuana; over the last few years, a variety of CBD-containing products have become legally available over the counter for a variety of uses. These products are supposed to only contain a minute amount of THC, but this is not always the case. When taken in high doses or combined with other cannabis products, CBD products will produce an intensified high and a much greater risk of adverse effects.

As with any other known or suspected overdose, summoning medical emergency assistance via 911 should be your first action. The 911 operator can usually give you instructions on how you can help the person until help arrives.

Treatment Options for Abuse of Legal Substances

Specific treatment for addiction to legal substances will depend on a variety of factors that each specific addiction treatment program will take into account. The biggest factor impacting treatment is the type of substance being abused, but the treatment course may also be affected by overall health, the extent of symptoms, degree of tolerance, co-occurring mental health disorders, and the individual’s expectations throughout treatment.

Addiction treatment should begin with detoxification guided by medical professionals, especially when it comes to serious cases of alcohol addiction, as withdrawal symptoms can be severe and even fatal in some cases.

Drug recovery programs are available in inpatient and outpatient settings, but most individuals experience the most benefit by starting with an inpatient program where they live full-time in a secure rehab environment, and then moving on to an outpatient program when they are ready to live at home and cope with that level of independence and lack of supervision.

Medications and behavioral therapy can help people recover from addictions to tobacco, alcohol, and OTC medications, and are offered at all types of addiction treatment programs. Behavioral treatments can range from providing self-help material to intensive counseling to help people recognize and change patterns of behavior and develop strategies for dealing with cravings. The goal is to work through issues and provide patients with tools they can use to facilitate a healthy life for the long-term.

Individuals in treatment for alcohol abuse may be given drugs such as naltrexone, acamprosate, and disulfiram, which encourage abstinence through effects like reducing cravings, preventing intoxication, and producing unpleasant physical symptoms when combined with alcohol.

For smoking cessation, the FDA has approved nicotine replacement therapy (NRT) like nicotine lozenges, gum, transdermal patches, inhalers, and nasal sprays. Varenicline (Chantix) and bupropion (Zyban) are non-nicotine medications that can be prescribed to support smoking cessation.

Although currently there are no FDA-approved medications for dextromethorphan addiction, treatment professionals can treat symptoms with medications such as muscle relaxants and pain relievers. Good nutrition and general health care are assets to a successful recovery from dextromethorphan or any substance.

Addiction recovery should be a continuing journey of growth, and it needs regular attention for long-term success. Long-term management includes a variety of group meetings and psychosocial support systems with ongoing medical supervision.