How substance misuse affects your body and mind 

There’s a lot more to substance use than just the immediate effects that keep you coming back for more, with long-lasting impacts on your mental and physical health. 

Substance use doesn’t just impact your mood and behaviour in the short-term, as you might expect. The long-term consequences of drug use are a big problem for every part of your body, and you might not even realise how far-reaching these effects are. Let’s take a look at what substances do to the body. 

Physical effects 

  • Organ stress 

Drugs affect your organs in many ways: your liver works overtime to try and process toxins, kidneys struggle to filter waste, your pancreas becomes inflamed, and lungs become irritated by inhaled substances.  

  • Weakened immune system 

Prolonged use of drugs can weaken the immune system, leaving you more susceptible to colds and illnesses. Some drugs interfere with your white blood cells, which are responsible for protecting your body from infection. 

  • Higher risk of infection 

As above, a weakened immune system makes it more likely you’ll develop infections, but drug use has also been associated with a higher risk of infections like HIV, tuberculosis (TB), and hepatitis B and C. This is because of the risk associated with sharing needles. 

– Nutrient deficiencies 

People who are addicted to drugs often neglect their basic needs, such as eating regularly. This can lead to malnutrition and vitamin deficiencies. 

– Cardiovascular weakness 

Drugs make your heart rate and blood pressure fluctuate, increasing the risk of heart attack, heart disease and stroke. 

Mental effects 

  • Mood swings  

You may feel heightened emotions, which can feel great when you’re feeling euphoric, but not so great when you’re struggling with negative feelings. You’ll also probably find that your mood fluctuates easily, e.g. going from happy to irritated in a short space of time. 

– Brain function 

Drugs have a negative impact on basic brain functions, including memory, learning and decision making.  

Depression and anxiety 

People who struggle with substance misuse problems are more likely to suffer from a mental health problem such as depression or anxiety. A preoccupation with drugs is likely to make you feel stressed and anxious too. 


Drug-induced psychosis often happens when you take too much, or if you’re mixing different substances. You might suffer from delusions, paranoia, or experience hallucinations, which can be scary for you and those around you. Psychosis can also trigger panic attacks. 


Drugs are highly addictive, and its effect on your brain means you’ll be chasing the good feeling you first got. You’ll find that you’ll need larger doses to get the same effect and will soon find it difficult to go without. 

The relationship between physical and mental effects 

The physical damage from substance misuse can have a big impact on your mental health, and vice versa. For example, pain from drug use can lead to depression, while depression can increase your cravings for drugs to help numb the pain.  

If you’re struggling with drug use and you’re experiencing any of the side effects listed here, don’t be afraid to reach out for help.