Recreational drugs and alcohol

Explains the mental health effects of recreational drugs, what might happen if you use recreational drugs and also have a mental health problem, and suggestions for where to find support.

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Can recreational drugs and medication affect each other?

When two or more drugs are taken at the same time (whether they are legal or illegal) they are likely to interact with one another, so that one drug changes the effects of the other. This means:

  • one or both of them may become toxic
  • their effects may be decreased or increased

Your age, weight, genes, general health and liver or kidney function will make a difference to the way the drugs work. However, there are some common interactions that many people experience.

Interactions between recreational drugs

Mixing drugs, or mixing drugs with alcohol, is always dangerous. The effects can be hard to predict, but there are some known interactions:

Drugs taken together


two or more depressants – e.g. heroin plus a benzodiazepine or alcohol

the depressant effect will be increased, slowing your heart and breathing – this may be fatal

two or more stimulants – e.g. cocaine plus ecstasy

can cause your heart to race (and can be very frightening) – this may be fatal

depressant(s) and stimulant(s)

can put a strain on your heart – can be fatal

cocaine and alcohol

  • produces a substance called coca-ethylene, which is poisonous

  • alcohol may suppress the effect of cocaine, so you may take more and overdose

ecstasy and cannabis

can make you anxious and paranoid

heroin and cannabis

very dangerous and easily fatal


can increase the euphoric effects of other drugs (such as opiates)

Interactions between recreational drugs and prescribed medication

These are some of the known interactions between drugs and psychiatric medication.

Drugs may also interact with any other type of prescribed medicines, as well as those bought over the counter.

Drugs taken together


MAOI antidepressants with many other drugs

can cause very dangerous effects, including very high blood pressure, chest pain, neck stiffness, rigid muscles, flushing, vomiting and severe headaches

reversible MAOI (moclobemide) with stimulants

may cause life-threatening effects, as above

chlorpromazine with amphetamine

the effect of both drugs may be reduced

lithium with cocaine

effect of cocaine reduced

lithium with amphetamine

effect of amphetamine blocked

lithium with alcohol or ecstasy

dehydration may cause lithium levels to become toxic

carbamazepine with cocaine

effect of cocaine reduced

carbamazepine with methadone

reduces methadone levels

ketamine with depressants (sedatives)

breathing reduced

most antidepressants, antipsychotics and tranquillisers with alcohol

  • increases sedative effects

  • loss of co-ordination and fine movement

first generation antipsychotics with ecstasy

increases risk of movement disorders

cannabis with clozapine and olanzapine (antipsychotics)

reduces amount of antipsychotic in body

citalopram (SSRI antidepressant) with cocaine

may cause brain haemorrhage (bleeding), high blood pressure and risk of bleeding – this effect was reported in July 2016 and may also apply to other SSRI antidepressants.

tobacco with clozapine and olanzapine

smoking reduces the effect of clozapine and olanzapine, so your dose of these drugs will need to be adjusted if you stop or start smoking (this is an effect of the hydrocarbons in the smoke, rather than the nicotine)

risperidone with cocaine

reduces 'high' of cocaine

This information was published in November 2016. We will revise it in 2019.

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