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The effects of substance misuse

Alcohol and drug misuse poses a significant risk to public health, with cocaine and cannabis being the most misused substances among adults in Ireland.

In this article, we discuss what happens in the body when you take drugs or drink alcohol, the side effects of substance misuse, and how to spot the signs of someone who may be struggling with drug or alcohol dependency. 

What happens in the body when you take drugs?

When a person consumes drugs, they are broken down by the liver, and a proportion of the drug and its metabolites are released into the bloodstream.

Some of the drug and its metabolites can then be detected in the body in different ways including via urine, saliva, hair and nails.

In the case of hair and nails, a proportion of the drug and its metabolites travel to the blood vessels in the hair follicles and nail bed.

Substances then become trapped in the hair shaft (medulla) and the keratin fibres of the nails, remaining in hair and nails as they grow, and making it possible to determine whether someone has consumed drugs, using hair and/or nail drug testing.

How a drug affects the body can depend on a variety of factors including the person’s age, weight, metabolism, the type of drug, how much of the drug is used, how often it is used, the person’s mental state when they take it, and whether they are taking other drugs at the same time.

What happens in the body when you drink alcohol?

When a person consumes ethanol – the intoxicating agent in alcoholic drinks – it is absorbed into the bloodstream, and more than 90% of it is broken down by the liver.

Alcohol metabolites are then excreted from the body in a variety of ways and can be detected using alcohol testing on a range of samples including breath, blood, hair and nails.

How alcohol affects the body can depend on a variety of factors, including age, gender, weight, and the type of alcohol the person has been drinking i.e. beers, wines or spirits.

As the alcohol travels to different parts of the body, including the brain, it begins to affect basic functions, such as movement, breathing and temperature control.

What is substance misuse?

Substance misuse – also known as substance abuse – commonly refers to the use of drugs or alcohol either in excessive amounts, or for purposes other than for which they are meant to be used.

This can include anything from drinking alcohol regularly and in large quantities, to taking illegal street drugs (e.g. cocaine, cannabis), or prescription drugs that have not been prescribed to you (e.g. opioids, benzodiazepines).

Routinely misusing drugs and/or alcohol can cause you to develop a harmful addiction or dependency, which can impact on every part of your life: from your job to your physical and mental health, personal relationships, and the health, safety, and wellbeing of others around you.

What are the signs of someone struggling with substance misuse?

The signs of someone struggling with substance misuse can vary depending on a variety of factors, including:

  • Their physical and mental state
  • Which substance(s) they are using
  • Frequency of use
  • How much they are using

However, there are some common signs that you can look out for, which may indicate that a person is struggling with substance misuse or dependency/addiction, including:

  • Lack of interest in personal grooming or appearance
  • Reclusive behaviour
  • Mood swings
  • Erratic or impulsive behaviour
  • Loss of interest in hobbies or social events
  • Lack of concentration
  • Reduced productivity at work or in educational settings
  • Increased risk taking
  • Weight changes

What are the side effects of alcohol misuse?

It is well documented that drinking alcohol chronically and excessively can cause short and long-term health complications.

However, the effects of alcohol on a person’s body can vary depending on several factors including their age, weight, gender, metabolism, the type/strength of alcohol they drink, how much and how often they drink, their mental state, and whether they use illicit drugs or prescription medications.

In Ireland, a single standard drink contains around 10 grams of pure alcohol. According to the HSE, women should consume fewer than 11 standard drinks (110g pure alcohol) over the course of one week, with a minimum of two alcohol-free days.

Men are advised to consume fewer than 17 standard drinks (170g pure alcohol) spread out over the week. Again, aiming for a minimum of two alcohol-free days.

This is considered lower-risk alcohol consumption.

However, people who drink more than the recommended amounts or who routinely binge drink may experience side effects including:

  • Depression
  • High blood pressure
  • Problems with the immune system
  • Impaired coordination
  • Slower reaction times
  • Slurred speech
  • Drowsiness
  • Nausea
  • Vomiting
  • Indigestion
  • Mood swings
  • Increased aggression and paranoia

More serious long-term complications from alcohol misuse can include alcohol-related liver disease (ARLD) and an increased risk of strokes.

Alcohol misuse has also been linked to the development of certain cancers including liver, mouth, throat, and breast cancer.

What are the side effects of drug misuse?

The effects of drug misuse on a person’s body can vary depending on several factors including their age, weight, gender, metabolism, which substances they are using, frequency of use, how much of the drug they are taking, and their mental state when taking them.

Different drug groups also affect people in different ways, depending on their chemical composition.

For example, stimulant drugs or ‘uppers’ such as cocaine, ecstasy (MDMA) and amphetamines can cause a person to feel more alert and energised.

Depressants, or ‘downers’ such as opiates (heroin, methadone, codeine) and benzodiazepines can cause a person to feel relaxed and drowsy.

However, some common side effects of drug misuse can include:

  • Weight changes
  • Dilated or constricted ‘pin prick’ pupils
  • Scabs, scars, or other skin problems (often caused by injecting drugs)
  • An increase or decrease in energy levels
  • Social withdrawal
  • Mood swings
  • Impaired focus and/or concentration
  • Increased risk-taking
  • Confusion and/or disorientation
  • Nausea and/or vomiting

More serious long-term complications from drug misuse can include organ damage, withdrawal symptoms when not using drugs, and certain mental health disorders.

People who inject drugs are also at greater risk of overdosing or contracting life-altering infections such as HIV, hepatitis B and hepatitis C. This risk is even greater among people who share needles.

How can I find out if a loved one is misusing drugs or alcohol?

Whether you suspect a loved one is struggling with substance misuse or require a drug or alcohol test for official matters, we are here to help.

We have over 15 years’ experience providing accredited drug and alcohol testing services for members of the public, the legal profession, and the workplace sector.

Our peace of mind Home Drug Testing Kit has been designed to give you peace of mind or enable you to seek support for someone who is struggling with substance misuse.

This easy-to-use, self-contained screening kit can detect drugs and their metabolites in a urine sample, with built-in test strips that allow you to read the results in just 5 minutes.

Need a private drug or alcohol test for official reasons (e.g. work, child custody proceedings, other legal issues)? Our toxicology laboratory can analyse a variety of samples including urine, saliva, blood, hair and nails for the presence of drugs/alcohol and their metabolites.

We also offer point-of-care breath tests, and alcohol monitoring using SCRAM CAM®.

For confidential advice about which test might best suit your needs, call our Customer Services team on 01 402 9466 or email.

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Marie Law AlphaBiolabs

Marie Law

Head of Toxicology at AlphaBiolabs

A highly-skilled and respected scientist with over 13 years’ experience in the field of forensics, Marie joined AlphaBiolabs in 2022 and oversees the company’s growing toxicology team.

As Head of Toxicology, Marie’s day-to-day responsibilities include maintaining the highest quality testing standards for toxicology and further enhancing AlphaBiolabs’ drug and alcohol testing services for members of the public, the legal sector, and the workplace sector.

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