Mixing Substances (Polydrug Use)

Mixing substances, also known as polydrug use, means using more than one substance at the same time or close together. This can include alcohol, illicit drugs, prescribed medication, or a combination of these.

Mixing substances is one of the biggest risk factors for overdose and serious harm. Harm reduction focuses on helping people understand these risks and reduce harm, without judgement or pressure to stop using.

Why mixing substances increases risk

When substances are mixed, their effects can combine or multiply in unpredictable ways.

Mixing can:

  • Slow breathing to dangerous levels

  • Increase the risk of overdose

  • Mask warning signs, leading people to use more than intended

  • Delay effects, causing accidental overuse

  • Increase strain on the heart, liver, and brain

Even substances that feel manageable on their own can become dangerous when combined.

High-risk combinations

Some combinations are especially dangerous.

Sedatives together

  • Alcohol and opioids

  • Alcohol and benzodiazepines

  • Opioids and benzodiazepines

  • Opioids and pregabalin

These substances all depress breathing. When combined, the risk of fatal overdose is much higher.

Stimulants and depressants

  • Cocaine and alcohol

  • Stimulants and benzodiazepines

Mixing stimulants and depressants can hide warning signs, increasing the risk of heart problems and overdose.

Prescribed and non-prescribed medicines

  • Mixing prescribed medication with alcohol or street drugs

  • Using medication in ways not prescribed

Always be cautious when combining medicines with other substances.

Cocaine and alcohol

Mixing cocaine and alcohol creates a substance called cocaethylene in the body.

Cocaethylene:

  • Puts extra strain on the heart and liver

  • Lasts longer in the body than cocaine alone

  • Increases the risk of heart attack and sudden death

Avoiding this combination significantly reduces risk.

Timing and tolerance

Risk is affected by:

  • How close together substances are taken

  • Reduced tolerance after breaks, illness, or treatment

  • Fatigue, dehydration, or poor health

Using the same amounts as before a break can be dangerous, especially when mixing substances.

Ways to reduce harm if mixing happens

The safest option is not to mix substances. If mixing does happen, harm reduction advice includes:

  • Use much smaller amounts

  • Space substances out in time

  • Avoid mixing sedatives

  • Stay hydrated and eat where possible

  • Avoid using alone

  • Carry naloxone if opioids are involved

Planning ahead can reduce risk in high-pressure situations.

Overdose risk and warning signs

Mixing substances increases the chance of overdose.

Seek urgent medical help if someone:

  • Is difficult or impossible to wake

  • Has slow, shallow, or stopped breathing

  • Has blue or pale lips or fingertips

  • Is confused, collapsed, or having seizures

Call 999 in an emergency.

Mental health and mixing substances

Mixing substances can worsen anxiety, panic, paranoia, and low mood, particularly during comedowns.

If mixing is being used to cope with stress or mental health difficulties, support is available to explore safer options and reduce harm.

Support from Wirral Ways

Wirral Ways offers confidential, non-judgemental support for people who mix substances.

You can access:

  • Harm reduction advice tailored to your use

  • Naloxone

  • Health checks

  • Needle and syringe services

  • One-to-one support and wellbeing services

You do not have to stop using substances to get support.

Get support

If you want to talk about mixing substances, overdose risk, or harm reduction support, contact Wirral Ways to find out what help is available.

Reducing risk can save lives. Support is here for you.

Last Updated on 10 February 2026