All drugs have an effect on your mental health. They affect the way that you behave, your mood and how you see things. These effects can be pleasant or unpleasant, short-lived or long-lasting, can go away or continue once the drug has worn off and they might even be similar to the symptoms you experience as part of a mental health problem. The way drugs may affect you can depend on a range of things: the type of drug, if it has been mixed with something else, how much you take, how often you take it, your mental state at the time you’re taking it etc. For some, taking drugs can lead to long-term mental health issues such as schizophrenia or depression. 

The possible effects of some of the most commonly used drugs are listed below. Not everyone will experience all of them. The possibilities can become greater if you already have an existing mental health problem. However, it is possible to develop symptoms of a mental health problem even without any previous history.

Alcohol – depressant.

This is legal but it’s also the most toxic. Moderate use is usually no problem and the long-term effects are associated with constant drinking over a long period of time, so they go away if you stop drinking.

  • Short term effects – feeling relaxed, more sociable, feeling subdued (so you drink more to recreate the pleasant effects) and when you drink a lot, uninhibited behaviour or aggression
  • Long term effects – memory loss, poor concentration, difficulty thinking clearly and difficulty problem solving
  • Withdrawal symptoms – delirium (confusion, hallucinations, disorientation) and anxiety

Amphetamines and methamphetamine (crystal meth) – stimulant.

The effects of crystal meth are similar to those of crack cocaine but they last longer. If you have a previous mental health problem, you are more likely to experience negative effects.

  • Short term effects – increased alertness and attention, increased energy and confidence, reduced tiredness
  • Long term effects – psychosis, paranoia, aggression, agitation, confusion
  • Withdrawal symptoms – depression, anxiety, irritability, tiredness

Benzodiazepines – depressant.

They are prescribed for symptoms of anxiety and as sleeping pills. These are illegal to take without being prescribed for them as they can be very addictive and hard to come off.

  • Short term effects – Negative effects: aggression, agitation, hostility. Positive effects: reduced tension and anxiety, feeling calm and relaxed, being able to think clearly
  • Withdrawal symptoms – anxiety, irritability, heightened awareness, problems sleeping

Cannabis (marijuana, hash, skunk) – stimulant, depressant and hallucinogen.

People use cannabis as a way to relax and get high. The effects that you experience will largely depend on the type of cannabis you use, how much you have, whether or not you are used to taking the drug and your genes (experiencing psychotic symptoms depends on whether you have a gene which codes for COMT (catechol-O-methyltransferase, a brain enzyme). If you have two copies of the COMT gene, you are more susceptible to psychotic experiences). If you have experience of depression and/or anxiety, you are more likely to experience the negative effects.

  • Short term effects – feeling relaxed, feeling hungry, finding things really funny, being talkative, feeling excited. High doses may cause: psychotic experiences (hallucinations), distorted perceptions, distress and confusion, forgetfulness
  • Long term effects – long-lasting symptoms of psychosis (which may be diagnosed as schizophrenia), depression later in life (if you used it a lot as a teenager)

Cocaine – stimulant.

It comes in two forms, cocaine powder (which is snorted) and crack cocaine (which is smoked). It is highly addictive and is really difficult to stop taking it.

  • Short term effects – being full of energy, feeling confident and wide awake. High doses may cause: hallucinations and delusions, depression, suicidal thoughts.
  • Long term effects – depression, anxiety, panic attacks, irreversible brain damage, worsening of pre-existing mental health problems, paranoia, repetitive movements
  • Withdrawal symptoms – psychosis, depression, loss of energy, akathisia (a feeling of intense restlessness)

Ecstasy (MDMA) – stimulant.

This is very dangerous to take at the same time as MAOI antidepressants. 

  • Short term effects – feeling happy and relaxed, feeling empathetic and being open and caring
  • Long term effects – depression (which won’t respond to antidepressants), anxiety, hallucinations, paranoia and panic attacks after repeated high doses, confusion, loss of confidence, agitation and teeth clenching

Heroin – opium related painkiller/depressant.

Heroin is a painkiller, prescribed as diamorphine. It is a very addictive drug and often leads to people committing crimes to fund their use of it.

  • Short term effects – a rush of pleasure followed by calm and warm contentment, drowsiness, becoming talkative, a loss of appetite, insomnia, feeling tired
  • Long term effects – a loss of appetite, loss of interest and enthusiasm, neglect of personal hygiene/safety, pain (when the level of drug in your system drops)
  • Withdrawal symptoms – craving (which can lead to serious crime to fund it), severe physical withdrawal symptoms, building a tolerance (so you need to take more of the drug to get the same effect)

LSD (lysergic acid diethylamide) – hallucinogen.

LSD causes you to lose your sense of reality and people have died from dangerous behaviour caused by its effects. 

  • Short term effects – detachment from surroundings, hallucinations, altered sense of space/time, feeling like you can fly, anxiety and feeling panicky (also known as “bad trips”, feelings of insight and spirituality
  • Long term effects – worsens existing symptoms of schizophrenia, having flashbacks of “bad trips” and feeling like you’re reliving them

Nicotine (tobacco) – stimulant.

You wouldn’t really experience mental health effects from using this, but because it is so addictive, stopping its use can cause negative effects.

  • Withdrawal symptoms – depression, irritability, restlessness


If you are having problems with drugs and they are affecting your mental health, contact a drug organisation, see your local NHS drug and alcohol service or visit your GP.