Driving Under The Influence of Drugs
Effect of Drugs on Your Driving Ability

Types of Drugs & Their Effect on Your Driving Ability

Updated Nov. 21, 2020

The following modules will address the dangers of drug use and how specific substances will affect your ability to drive. Before we delve into specific drugs and their effects, let’s look at drug “types”. There are thousands of different drugs, each with a distinct chemical make-up that exerts a unique effect on human bodily functions.

Most drugs fall under one of three categories:

  • Stimulants: speed the body up.
  • Depressants: slow the body down.
  • Hallucinogens: alter thought processes and perception.

If you know which category a substance falls into, you will have a general idea about how it will affect your body and mind. It is worth noting that a few drugs do not cleanly qualify as a stimulant, depressant or hallucinogen but may have attributes from two of these categories. We will discuss this in a little more detail later.

Drugs from each of these categories have a broad range of short-term effects, some of which are positive in terms of illness-treatment and symptom-management. Others, such as paranoia and hallucinations, are decidedly less positive. The long-term effects of drug use may include heart, lung, liver and brain diseases, gastrointestinal problems, reduced libido, mental health issues, permanent disability and even death.

Taking any drug – legally or otherwise – can render you unsafe to drive. It is your responsibility to make sure you are attentive, alert and physically capable of controlling your vehicle while driving. You can be convicted of DWI (driving while intoxicated) or DUI (driving under the influence) if a law enforcement officer believes that the drug in your system is impairing your driving ability – even if the drug in question is your prescription pain medication.

What are narcotics?

Another term you may hear in relation to drugs is “narcotics”. In the medical community, a narcotic is any drug that dulls the senses, lessens pain and causes drowsiness. This word may be used to describe drugs like opioids, barbiturates and other common medications used to treat severe pain. Narcotics are extremely addictive and have a high potential for misuse. Opium, morphine, codeine and heroin are some of the most dangerous and frequently abused narcotics. Abuse of narcotics can result in memory loss, sleepiness, nausea, shallow breathing and irregular heart rhythm.

It is important to realize that while narcotic drugs are frequently prescribed as painkillers, their “legal” status in this regard does not make them much safer than illegal opiates and similar substances. In 2013, there were 43,982 deaths caused by drug overdose in the United States. Of these fatalities:

  • 22,767 were caused by prescription drugs.
  • 16, 235 involved opioid pain medications.

In law enforcement, the word “narcotics” may be used to refer to any drug or substance from the Controlled Substances Act, which may include cocaine, LSD, methamphetamine and marijuana.


Any substance that qualifies as a stimulant will speed-up and amplify your bodily functions. The short-term effects of stimulants include rapidly increased heart rate and respiration, increased energy, an acute state of “alertness” and loss of appetite. Stimulant drugs can also create a very short-term sense of extreme happiness and well-being, as they activate the brain’s dopamine pathways.

Here are some well-known stimulant drugs:

  • Nicotine (the highly addictive, mind-altering substance in tobacco)
  • Cocaine
  • Ritalin
  • Adderall and other amphetamines
  • MDMA (ecstasy)
  • Methamphetamine

Nicotine is probably the most widely used stimulant and is legal, despite being incredibly harmful. Very small quantities of nicotine may reduce anxiety and relieve pain. These effects are very short-term and are replaced by heightened anxiety and greater pain sensitivity as soon as the drug wears off.

The short-term effects listed above may sound positive, but they are extremely dangerous. Your body’s essential systems are not capable of running that quickly for a sustained time. Stimulants can cause:

  • Extreme anxiety
  • The inability to focus on one task
  • Poor muscle coordination
  • Muscle shakes or tremors
  • Overexcitement and the inability to calm down
  • The inability to see danger or recognize risk
  • Heart attacks, heart failure
  • Dangerously high body temperature

We do not have to consider these effects too deeply to understand what a devastating impact they would have on your driving ability.


Depressant drugs have the opposite effect of stimulants. They slow down, cut-back and impair bodily functions. The short-term effects of depressants include sleepiness, lethargy, loss of physical sensations, muscle paralysis, poor coordination, dramatically slowed digestion, slow heart rate, slow respiration and a false sense of calm and well-being. Due to these effects, pharmaceutical depressants are frequently prescribed as pain relievers, anti-anxiety medications and sedatives to treat sleep disorders.

Common depressant drugs include:

  • Alcohol
  • Antihistamines (allergy medication)
  • Pain killers
  • Opioids (such as Oxycontin and heroin)
  • Tranquilizers (such as Xanax)

Long-term or excessive use of depressants can slow down bodily functions to the degree that they stop working altogether. Prescription pain medications are particularly dangerous as the body adapts to their effects over time, so the patient steadily needs larger and larger doses to achieve the same level of relief. This is why prescription pain medication overdoses are so tragically common.

Pain relievers dull the senses and block the nerve pathways that make the brain aware of pain. They can also lower fever and reduce inflammation and are commonly prescribed to treat chronic inflammatory diseases as a result. Unfortunately, they can also cause:

  • Extreme light sensitivity
  • Increased risk of heart attack, stroke and heart failure
  • Liver damage
  • Thinning of the blood (which can lead to excessive bleeding)
  • Wearing away of the stomach lining

These last two negative side effects can be fatal in patients who use anti-inflammatory pain killers long-term. As the stomach lining is worn away, ulcers can form when stomach acid comes into contact with the stomach wall. If the patient is also suffering from thinned blood, this can result in internal bleeding.

Many pain killers are available without a prescription, usually when they are diluted with other, less-harmful drugs. Medications that contain opioid painkillers are particularly dangerous and addictive and as such, are strictly regulated. Whether available over the counter or not, an overdose of any pain killer can be fatal. For example:

  • Aspirin, Tylenol and Advil can cause irreparable liver damage.
  • Morphine and Codeine (opioids) carry increased risk of addiction and overdose, and can result in nausea, slowed respiration, skin irritations, constipation and depression.
  • Heroin, hydrocodone and methadone are more potent opioids than those listed above, carrying an even greater risk of physical addiction and overdose.


Any drug which alters a person’s perception of themselves and the world around them is considered a hallucinogen. They can cause extremely vivid hallucinations (vision, smell, taste and touch) mood disturbances, distortion of time and an acute sense of detachment. Some hallucinogenic substances occur naturally, while others are man-made.

The effects of hallucinogenic drugs vary greatly from person to person, as they depend on the personality and current mental state of the user. While many have reported taking hallucinogenic drugs to be a resoundingly positive experience, others experience devastating, negative effects. There is no way to predict how you will react to a hallucinogen, though the effects often include:

  • Anxiety, fear and panic.
  • Depression and suicidal thoughts.
  • Nausea, sweating and rapid breathing.
  • Dangerously increased body temperature and heart rate.
  • A false sense of happiness and well-being.
  • Paranoid delusions and vivid hallucinations (which may be pleasant or incredibly frightening).
  • Psychosis (which may continue even after the drug has left your system).

Marijuana is possible the best known and most widely used hallucinogen. This unusual drug does not fit clearly into a single category; many people report marijuana having a depressant effect, while others experience effects like those caused by stimulant drugs. The variation in effects seems to depend on the individual user’s psychological state and physiology, in addition to the strain of the drug being taken.

In 2017, it was estimated that roughly one in seven adults around the United States uses marijuana on a regular or semi-regular basis. The drug is used recreationally, primarily for its ability to create a sense of well-being, hallucinations and an altered sense of self. While there is less potential for overdose and death as a result of marijuana use (indeed, there is not one confirmed case of this having occurred), the drug can still be incredibly dangerous. Marijuana causes detachment, disorientation and confusion, which can leave the user unable to protect themselves or react appropriately to their current surroundings. This would be an extremely dangerous state of mind to contend with while trying to drive a car.

While it is unlikely to cause death by overdose, marijuana can irreparably damage a person’s mental well-being. It has been known to result in memory impairment, panic, paranoia, anxiety and full-blown psychotic breaks.

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