Drugs and alcohol

Lesson Progress:

Some medicines you can buy over the counter (such as hay fever medicines or cold remedies) as well as some prescription medicines can make you drowsy or have other side effects. This can affect your overall ability and judgement and mean you are not safe to be on a construction site and not fit to drive or operate machinery. You should read the label or speak to the pharmacist if in doubt. You must let your employer know if you have to take any medicines at work.

Many employers and clients have policies to carry out random testing for drugs and alcohol.

Anyone caught working under the influence of illegal drugs, some types of medicine or medication, psychoactive substances (known as ’legal highs’) or alcohol may have to leave site immediately and could lose their job.

Effects of drugs and alcohol

Regardless of if it is a medicine, alcohol, or any type of drug, any person under the influence of any substance, while at work, is a danger to themselves and everyone else on site. They are likely to suffer from the following.

  • Poor or irrational decision making.
  • Distorted vision.
  • Slow reaction times.
  • Mental confusion.
  • Clumsiness.

The effects and traces of some drugs can stay in the body for long periods, even after users think the effects have worn off (for example, cannabis can be detected during testing several weeks or even months after it has been taken). Unlike alcohol, there are no permitted safe levels for illegal drugs so a trace could mean failing a drugs test. This includes drugs referred to as ‘legal highs’ (psychoactive substances).

Psychoactive substances

Psychoactive substances are designed to produce similar effects to drugs (such as cocaine and ecstasy). They were known as ‘legal highs’ until changes to the law in 2016, making them illegal under the Psychoactive Substances Act.

In 2015 there were over 100 deaths involving psychoactive substances. Five out of six deaths were males. Most deaths involving psychoactive substances happen in people aged 20 to 29 and the average age for deaths of this type is 28 years old.

It is an offence under the Psychoactive Substances Act to possess with intent to consume, produce, offer to supply, supply, import or export any substance for human consumption which is capable of producing a psychoactive effect. Offences are punishable by a fine or up to seven years’ imprisonment.

Illegal drugs

The maximum penalties for illegal drug possession, supply (dealing) and production depend on the type or class of drug. Examples of maximum penalties are outlined in the table below.

ClassExamples of drugsPossessionSupply and production
A.Crack cocaine, cocaine, ecstasy (MDMA), heroin, LSD, magic mushrooms, methadone, methamphetamine (crystal meth)Up to seven years in prison, an unlimited fine or bothUp to life in prison, an unlimited fine or both
B.Amphetamines, barbiturates, cannabis, codeine, ketamine, methylphenidate (Ritalin), synthetic cannabinoidsUp to five years in prison, an unlimited fine or bothUp to 14 years in prison, an unlimited fine or both
C.Anabolic steroids, benzodiazepines (diazepam), gamma hydroxybutyrate (GHB), gamma-butyrolactone (GBL), piperazines (BZP)Up to five years in prison, an unlimited fine or bothUp to 14 years in prison, an unlimited fine or both


Depending upon your employer or site policy the blood alcohol level needed to pass a test can be less than the legal driving limit.

Besides being a danger to themselves and others, anyone under the influence of alcohol at work risks losing their job and livelihood. Many people convicted of drink driving were driving the morning after drinking the night before. Most people seriously underestimate the length of time it takes to sober up.

The effects of alcohol can last for hours

On average it takes one hour for your body to get rid of one unit of alcohol.

A unit is the volume (litres) x ABV (% alcoholic strength of the drink).

  • One pint of beer at 5% strength is 2.8 units.
  • Five pints of beer at 5% strength is 14 units.
  • One 200 ml glass of wine at 13% strength is 2.6 units.
  • One 25 ml shot of a spirit at 40% strength is 1 unit.
  • One 275 ml bottle of alcopop at 5% strength is 1.4 units.

If someone started drinking at 19:00 hrs and drank five pints of beer with a strength of 5% it could be up to 10:00 hrs the next morning before all the alcohol is out of their system. However, this time can change depending on things like your size, weight, age, when you last ate and how much sleep you have had.

From January 2016 the Department of Health recommends that alcohol intake is limited to 14 units per week (two units per day) for men and women.
There is no safe limit of alcohol that you can consume and then drive or operate machinery safely.
For further information on alcohol visit the Drinkaware website (www.drinkaware.co.uk/alcohol-facts/).