Signs of Drug Use in Employees: Behaviors That Might Signal Drug Use on the Job

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5 September 2023

Signs of Drug Use in Employees: Behaviors That Might Signal Drug Use on the Job

Understanding how to recognize the signs of drug use by employees is among the most serious and nerve wracking responsibilities for a supervisor. On the one hand, maintaining a drug-free workplace helps keep workers and property safe by avoiding accidents and injury, violence, and theft. (Learn more in "The Importance of a Good Drug and Alcohol Policy in the Workplace ".) On the other hand, suspecting that a worker is using drugs or is intoxicated on the job and initiating reasonable suspicion testing can have serious consequences for the employee, and the supervisor or company if done incorrectly.

With such serious consequences it is important that you be able to reliably identify the signs of drug use and intoxication, especially when safety sensitive positions are involved. (Learn more in "Prescription Opioids and Safety Sensitive Work".) To insure that your company’s workplace drug policies and procedures are followed, you also need to understand that policy and how to implement it. Your human resources department can provide training and guidance on this topic.

Initial Warning Signs of Possible Substance Abuse

The first sign of a problem is often dramatic changes in behavior or performance.

For example, a top performing employee is suddenly making a lot of mistakes on the job or a normally reliable employee is consistently showing up late with no real explanation. These shifts do not necessarily mean drug use, but they often mean something has changed for the employee and needs to be addressed and reasons for the new behavior found.

There is no one set of behaviors to look for. The key is that the person is acting drastically different from how they normally do.

Further Signs of Illicit Drug Use or Intoxication

Understand that supervisors are not expected to identify which illicit drug the employee may be using. That will be determined by the reasonable suspicion drug test if/when it’s administered. Supervisors are expected to identify and document the physical appearance, behavior(s), and/or job performance that strongly suggest illicit drug use or intoxication so that drug testing for suspicion can be conducted when necessary. As with all things related to the body, there may be many medical explanations for any symptom seen. This is why drug testing for suspicion is just that, for suspicion. None of these indicators are guarantees of drug activity. (Learn more in "8 Things Employers Should Know About DOT Drug and Alcohol Testing".)

Physical appearance can change with illicit drug use or intoxication. As for behavior, there are four areas that can be changed by illicit drug use or intoxication. They are:

  • Psychomotor activity
  • Social behavior
  • Speech patterns
  • Personality
Free Download: What Your Company's Drug and Alcohol Policy May Be Missing (and How to Get It Right)

Attention to be paid to both physical appearance and behaviors when you are making observations. Here are some specific things to look for:

Physical appearance

  • Appearing messy
  • Dirty or smelly body
  • Dirty or stained clothes
  • Burns on clothes or body
  • Being partially dressed
  • Puncture marks on the skin
  • Watery eyes
  • Bloodshot eyes
  • Glassy eyes
  • Dilated pupils
  • Constricted pupils
  • Unable to keep eyes open
  • Red or flushed face
  • Pale skin tone
  • Sweaty
  • Slobbering
  • Dry mouth
  • Runny nose
  • Shakiness or tremors
  • Alcohol odor
  • Chemical odor
  • Pungent tobacco odor
  • Mouthwash or breath spray smell
  • Chewing gum
  • Candy

Psychomotor activity

  • Holding on to something or someone else to steady themselves
  • Stumbling
  • Unable to walk
  • Staggering
  • Swaying
  • Falling
  • Standing with their feet wide apart as to steady themselves
  • Standing rigidly
  • Fumbling
  • Jerky actions
  • Nervous actions, like finger tapping, tugging at hair, etc.
  • Grinding teeth
  • Hyperactivity
  • Slow movements
  • Disoriented
  • Sleepy or drowsy

Social behavior

  • Talkative
  • Withdrawn
  • Sarcastic
  • Overly polite
  • Belligerent
  • Excited
  • Inattentive
  • Tearful or crying
  • Aggressive or fighting
  • Mood changes
  • Mentally impaired

Speech patterns

  • Slurred speech
  • Shouting
  • Whispering
  • Incoherent speech
  • Rambling speech
  • Slow speech


  • Mood changes
  • Erratic behavior or responses
  • Non-communicative
  • Profanity
  • Hostility

Actions After Suspicion

Your human resource department, and your company's workplace drug policy, can advise you on your company’s specific process for documenting possible drug use and intoxication in the workplace. Here are a couple of points to keep in mind.

Base your decisions on first-hand observations. Do not rely on hearsay or a general suspicion. You must have observed the questionable physical appearance, behavior, or performance yourself.

Have second person act as a witness. Ideally, the second person is also a supervisor or someone who has received training on how to apply your company’s workplace drug policy.

Document your observations, not assumptions. Some companies use a checklist to document the supervisor’s observations of questionable behavior.

Be aware that some of the symptoms often blamed on alcohol intoxication and hangover can be the result of legitimate causes. The employee could be physically ill, experiencing severe stress or fatigue, be under emotional distress, or experiencing ketosis.

Document two or more signs before deciding whether to take action. Observing a single red-flag behavior is not enough justify taking action on the suspicion of illicit drug use or intoxication. You must observe and document substantial change from the person’s normal appearance, behavior, and/or job performance.

The one exception to this rule of thumb is when the employee’s actions or behavior results in an imminent danger of injury or harm to themselves or others. Never sacrifice workplace safety.

Bring human resources into the process as early as possible.

Human resources can act as your “guide on the side” answering any questions that come up, insuring that policies are followed and workers’ rights are honored.

Key Differences on Alcohol Use and the Workplace

Remember is that alcohol is not an illegal drug and alcohol use is not illegal (although it is regulated). In most situations, as long as the person drinking is of legal drinking age, the employer has no issue with an employee having a drink while away from work.

For certain safety sensitive jobs, like flight crews and train operators, employees can face special restrictions on their alcohol consumption away from work. For these jobs employers can impose extra requirements. For example, commercial airline pilots can’t consume alcohol for eight hours before flying.

Additionally, having a hangover that impairs the employee’s mental and/or physical abilities is also an issue for employers. If you suspect an employee is hung over at work, use the same process as if that employee were drunk or high to document their appearance, behavior, and/or performance.

Being able to identify and document the signs of illicit drug use and intoxication on the job is a key set of skills for a supervisor to help ensure workplace safety.