What are the signs of drug use in the workplace?

Alex Swann

Alex Swann

on Feb 18, 2021

Signs of drug use can sometimes be tricky to spot - especially if you are unsure as to what to look for. But for employers, it’s important to know these signs to make sure your employee can get the support that they need.


Statistics show that drug abuse costs the UK £15 billion per year, and that 60% of all poor job performances and 40% of industrial accidents are linked to substance abuse. 

A comprehensive drug testing policy and strategy is crucial to reducing substance-related issues in the workplace. While many employers choose to implement random drug tests for existing employees, many will also include a clause that allows testing if they have a strong reason to believe that an individual is affected by substance misuse. In order for this approach to work, however, you’ll need to know what to look out for. 


What are the signs of drug use? 

While certain signs can be seen across a variety of different substances, there are also some relevant to just one or two drug types. Similarly, some of these signs may also indicate other concerns - anything from a common cold to mental health issues - so should be used in conjunction with other observations plus a comprehensive workplace drug testing programme, rather than as standalone evidence of substance misuse.



It is important to remember that these signs of drug use may not be purely physical, but also behavioural and psychological.


Physical signs of drug use

  • Changes in physical appearance
  • Worsening personal hygiene
  • Impaired reaction times
  • Slurred speech
  • Impaired awareness
  • Sudden incapacity
  • Restricted mobility
  • Distorted hearing or vision


Behavioural signs of drug uses

  • Poor job performance
  • Bad time-keeping
  • Greater levels of absence through short-term sickness
  • Worsening relationships with management, colleagues or customers
  • Dishonesty and theft
  • Atypical or erratic behaviour
  • Lowered ability to successfully carry out everyday tasks
  • Reduced levels of perception and coordination
  • Big fluctuations in energy or concentration
  • Lack of reasoning


Psychological signs of drug use

  • Lack of memory
  • Limited judgement
  • Unusual irritability or aggression
  • Tendency to become confused
  • Sudden mood changes


Can dilated pupils be a sign of drug use? 

In short, yes, dilated pupils can be a sign of drug use. However, different substances will have different effects on the look of a user’s eyes.



Dilated pupils

Certain drugs can work on neurotransmitters in the brain, affecting either the sympathetic or parasympathetic nervous system (or both) to cause dilation of the pupils. This is a sign of psychotropic substance use, but also occurs with other substances: 

  • Amphetamines
  • Methamphetamines
  • Cocaine or crack cocaine
  • Hallucinogens, such as LSD or magic mushrooms
  • Opiates, such as prescription painkillers
  • Heroin 
  • Marijuana
  • Speed


Constricted pupils

Constricted - or ‘pinpoint’ - pupils are generally caused by the effects of drugs on the parasympathetic nervous system. It will often be a sign of narcotics use, but can also stem from the use of some other substances:

  • Heroin
  • Morphine
  • Oxycodone
  • Fentanyl
  • Methadone
  • Codeine
  • Hydrocodone


Red eyes

Conjunctival redness - or bloodshot eyes - can be a symptom of the use of various drug types. You may also find that an employee is using eye drops more regularly, in an attempt to hide this redness. Drugs that can cause red eyes include: 

  • Marijuana
  • Cocaine or crack cocaine
  • Benzodiazepines (such as Xanax)
  • Depressants, such as sedatives

Image source: 


The use of illegal drugs can result in a number of physical, behavioural and psychological signs in an individual -  and recognising these signs can help you to crack down on drug misuse in the workplace. However, it is important to note that simply spotting these signs is not enough. With a comprehensive workplace drug testing policy and strategy in place, you can identify and resolve these issues early on, making your workplace a safer place, and helping affected individuals to get the support that they need.


To learn more about drug and alcohol testing in the workplace, take a look at our e-learning resources.

Main image: Pixabay - no attribution needed


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