Different drugs have different effects on your body.
But common effects include problems with:
- your heart and other organs
- infections and how your body can fight infections
- dependency and brain changes
- fertility
- your mouth, teeth and gums
Some problems can happen even if you do not use drugs that often. But the risks increase if you take too much at a time or use drugs for a long time.
You can find out more about the effects of specific drugs in our drugs A to Z.
The information on this page is about non-medical use of drugs. To learn more about a medicine prescribed to you, ask your GP or pharmacist. You can also check the leaflet that comes with the medicine.
What we mean by non-medical use of a medicine
Non-medical use is when someone uses a medicine in a way that does not follow medical guidelines.
This can include when someone uses a medicine:
- they bought in the illegal drug market - this can be online or in person
- that was not prescribed to them
- in a different way or quantity than their doctor prescribed
How drugs affect your organs
Drug use can cause damage to many organs and systems, including your:
- heart
- liver
- kidneys
- bladder
- nose - if you snort drugs
- lungs - especially if you smoke drugs or use inhalants
The risk increases if you:
- have health problems or a family history of them
- take too much of a drug at a time
- use drugs regularly
- take more than 1 substance at a time - including alcohol and medicines
- mix drugs with tobacco
Heart problems and drug use
Most drugs cause short-term changes to your heart rate. They can make your heart beat faster or slower.
Other heart problems linked with drug use include:
- irregular heart beat
- high blood pressure
- angina - chest pain caused by reduced blood flow to the heart muscles
- heart disease or other problems with your arteries
- stroke
- heart attack
- damage to your heart tissue or valves
- collapsed veins - if you inject drugs
- heart infections
- problems with clotting
The risk is increased if you:
- have heart problems or a family history of them
- use drugs regularly
- use drugs such as cocaine, amphetamines or MDMA
- smoke cannabis regularly
- inject drugs
- take too much of a drug at a time
- take more than 1 substance at a time
Bladder problems and ketamine
Regular use of ketamine can cause problems with your bladder and urinary system. This may be called ketamine bladder.
The symptoms include:
- tummy pain (k cramps)
- pain or other problems peeing
- changes to when or how often you pee
- unintentional peeing (urinary incontinence)
- blood in your pee
Infections and drug use
Drug use is linked with certain infections or getting infections more often.
This can be because of:
- sharing needles
- sharing equipment to snort drugs
- effects on your immune system - using drugs can reduce your body's ability to fight infections
Infections linked with sharing equipment to use drugs include HIV and hepatitis C.
Some drugs cause a high sex drive or reduce your inhibitions. They can make you do things you would not usually do. For example, have unprotected sex. This increases your risk of sexually transmitted infections (STIs).
Drug dependency and effects on the brain
Drug use can cause short-term and long-term changes in your brain.
When you take a drug, it can affect areas of the brain related to pleasure. The intense feelings can make you want to keep taking the drug.
But if you start taking the drug more often, it can lead to:
- dependency - you get cravings for the drug or feel you need it to do certain things
- tolerance - you need to take more of the drug to get the same effects
The risk of dependency is increased if you:
- have a family history of drug or alcohol problems
- have a mental health difficulty such as anxiety
- are neurodiverse - types of neurodiversity include autism or attention deficit hyperactivity disorder (ADHD)
- have a history of trauma or difficult family situations
- started using alcohol or drugs at a young age
- use certain drugs - for example, opioids, cocaine and G (GHB or GBL) can cause dependency quickly
If you stop taking certain drugs after regular use, you can get withdrawal symptoms. Coping with withdrawal symptoms is often why people continue to use drugs even when they want to stop.
Long-term changes to the brain
Long-term drug use can change areas of the brain related to:
- judgement and decision-making
- learning and memory
- reward and pleasure
It can make it harder to feel pleasure from everyday things. For example, eating food, listening to music or having sex.
These are physical changes to your brain that can last after you stop using the drug. But with time and the right support, the brain can recover.
Mouth problems and drug use
Regular use of certain drugs can cause problems with your mouth, teeth and gums.
Mouth problems linked with drug use include:
- dry mouth
- tooth decay
- ulcers on your gums
- grinding your teeth
- clenching your jaw
Helping your body recover after drug use
There are things you can do to help your body recover from drug use or during a comedown.
You could try to:
- reduce or stop drugs and alcohol for a while
- get enough sleep or rest
- eat well
- do some physical activity - it releases chemicals in your brain that improve your mood (endorphins)
- do some exercises to manage stress, anxiety and worry
It may also help to quit smoking if you smoke. Smoking can cause anxiety as well as other health conditions.
When to get help for drug use
Some drugs can cause permanent damage to your body. It is important to get help early if you use drugs and have health problems.
If you see a GP about any symptoms, it's best to tell them about any drug use. It will help them to recommend the right treatment.
If you're worried about talking to your GP
Your GP is there to help you. They talk about things such as drug use all the time.
But if you feel uncomfortable talking about your drug use or symptoms, you could:
- write down what you need to say before your appointment - you can give your notes to your GP if you need to
- tell your GP how you feel - this can help you feel less nervous
- use everyday words - you do not need to know medical terms
Non-urgent advice: Contact a GP or drug service if you:
- are worried about your wellbeing
- think drugs are affecting your health, relationships or work
- cannot stop using a drug
- continue to use drugs even though it causes you harm
- are at risk of infections - if you ever shared needles or had unprotected sex
- think you have withdrawal symptoms
Non-urgent advice: Drugs and alcohol helpline
You can contact the helpline for support, information or advice on treatment and support options.
Freephone: 1800 459 459
Monday to Friday, 9.30am to 5.30pm
Email: helpline@hse.ie