Introduction to the 4 Panel Drug Test

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5 September 2023

Introduction to the 4 Panel Drug Test

What Is a 4-panel drug test?

Each drug that is screened during a drug test is referred to as a panel. The 4-panel test is the least comprehensive test, but it can be a cost-effective method of testing for some of the more commonly abused drugs found in workplaces. There isn’t a standard definition of the 4-panel drug test and it is often customized to fit the culture or demographics of your workplace. It may also take into consideration professional expectations and state laws.

The usual difference between the 4-panel and Department of Transportation (DOT) 5-panel test is the elimination of marijuana/cannabis from the test. (Learn more in Introduction To The 5 Panel Drug Test). Culture and the laws regarding the recreational and medical use of marijuana are rapidly loosening and levels of use in specific geographic areas are evolving alongside these cultural and legal changes. As a result, far more people use marijuana in the Northeast and on the West Coast, particularly in states where recreational use is legal. But even though recreational marijuana is now legal in many states, it is still a restricted drug in federal laws, meaning you are perfectly within your rights to test for it.

There is some concern that tests can detect THC, the active ingredient in marijuana, weeks after use and with a tight labour market some companies are choosing to drop marijuana from their test panels. Occasionally however, marijuana will be included, and PCP excluded. This makes sense when demographics or workplace culture suggest marijuana could be an issue. The 4-panel test, like any drug test, is customizable. (Learn more in Drug Test Types: When To Use 5, 7 or 12 Panel Urine Screening).

A 4-panel drug test could typically include any combination of these drugs:


Cocaine is a highly addictive drug made from the leaves of the South American coca plant. As with many illicit drugs, cocaine use can make employees unproductive and unreliable, affecting workplace morale and overall productivity. Even when it is used off company hours, the after-effects for your employees can be severe.

It is a difficult drug for employers to spot outside of specifically testing for it. Often its immediate effects are mistaken for normal workplace stress. Constant sniffing, nosebleeds, sudden weight loss and restlessness are some of the more noticeable symptoms.

Other effects of cocaine use include:

  • Poor or impulsive decision making
  • Frequent mood swings
  • Leaving office frequently to use bathroom or take phone calls
  • Talking endlessly, often about seemingly unrelated subjects
  • Aggressiveness
  • Feelings of euphoria and energy
  • Hypersensitivity
  • Irritability
  • Paranoia
  • Dilated pupils

As with many drugs, cocaine users frequently require higher and higher doses to get the same effects, which leads to both addiction and a stronger possibility of an overdose.


Marijuana is the most commonly used illicit drug in the United States, according the federal government. However, it is gaining acceptance for both medical and recreational use. Medically, it can be used to relieve pain, nausea or other symptoms. Thirty states have now legalized the use of medical marijuana and nine states plus Washington, D.C. have legalized the use of recreational marijuana. (Learn more in Medical Marijuana: The Potential Impact On Your Workplace).

While the effects of marijuana can be felt almost immediately when it is smoked, the effects of marijuana that is ingested are usually delayed by thirty to sixty minutes.

Short term effects of marijuana use include:

  • Altered senses
  • Changes in mood
  • Impaired body movement and memory
  • Difficulty with thinking and problem solving

High doses of marijuana can also result in psychosis, hallucinations and delusions. Over the long term there is some evidence that marijuana use has a negative effective on brain development. Increasingly higher doses of THC are being found in marijuana in recent years, which is exacerbating its negative effects.

In the workplace marijuana can negatively affect those involved in cognitive and safety sensitive positions or tasks putting your business, workers and others at risk.


Phencyclidine (PCP) is a dangerous and mind-altering drug and has no legal uses. Users tend to be younger people and primarily, but not exclusively, men.

PCP has numerous effects that include:

  • Numbness
  • Loss of coordination
  • Sweating
  • Shallow respiration
  • Rise in blood pressure and pulse
  • Sense of strength and invincibility
  • Hallucinations
  • Psychosis

PCP is highly addictive. There is a high risk of self-injury with PCP use, but your workplace can also be put at risk due to impaired judgement, extreme physical exertion and even violent behavior in users. The 4-panel drug test that includes PCP will identify users and your workplace drug and alcohol policy should include guidelines for dealing with the illegal use of drugs like PCP in the workplace.


Amphetamines, including methamphetamines, are stimulants that speed up the central nervous system.

The effect of amphetamines ranges widely from person to person. They can give one person a sense of euphoria and invincibility, make another nervous and tense and make another openly hostile and aggressive. Additional effects include:

  • Lack of appetite
  • Increased blood pressure and heart rate
  • Sweating
  • Headache
  • Nausea
  • Fast and irregular heartbeat
  • Blurred vision
  • Loss of coordination

Amphetamines are also highly addictive, and their illicit use can have serious short and long-term effects including risky, bizarre and violent behaviour, hallucinations, and paranoia. In the workplace, even some of the milder effects of amphetamine abuse can be dangerous, putting workers and customers at risk. The excessive mood swings experienced by amphetamine misuse can also affect customer service. Your worker may exude confidence and be overly talkative with customers one minute and then hostile and aggressive the next.

Prescribed and controlled use of amphetamines is not usually an issue in the workplace. Problems generally occur when users take more than they are prescribed or use them illegally. Your 4-panel drug test can identify users and the Medical Review Officer (MRO) can ensure any users are adhering to a legal prescription.

Basic Opiates

Opiate is a term originally used to describe naturally occurring drugs, known as alkaloids, that are made from the opium poppy plant. It now often includes both synthetic and semi-synthetic compounds. Basic opiates include opium, codeine, and morphine. Heroin, another opiate, is an additionally refined version of morphine that was originally manufactured as a treatment for tuberculosis and as remedy for morphine addiction. Neither heroin or opium are used medically in the United States, although codeine and morphine are frequently prescribed pain medications. These drugs have both analgesic (painkilling) and narcotic effects, including feelings of euphoria.

Even legal opiates are highly addictive and susceptible to substance abuse. In fact, according to national surveys, over 75% of those with opiate abuse problems are in the workforce. In your workplace, opiate abuse can have a negative effect on productivity and absenteeism as well as overall morale. It can increase the costs for things such as healthcare. Opiate use at work can put both the user and coworkers at risk. It can cause severely slowed breathing which, in turn, can lead to coma or permanent brain damage, and overdoses from this drug are relatively common. Additional effects can include:

  • Flushed skin
  • Drowsiness
  • Nausea
  • Severe itching
  • Swelling of the face, throat, eyes, lips and mouth
  • Diminished mental function
  • Slowed heart rate

What else do I need to know about the test?

Demographics, including the age, sex and location of your workforce, should play a role in your decision about what to include in a 4-panel test, but be cautious with generalizations and stereotypes. For example, while marijuana use does tend to be more prevalent among young adults, its use among baby boomers has more than doubled according to one study.

Regardless of what you choose to include, you’ll want to ensure you have a comprehensive drug and alcohol policy to deal with any positive results found during your tests. These policies should include an education component that provides workers with information about the dangers of drug use as well as any punitive measure you may want to include.