People take more than one type of drug for many reasons; to lessen the negative effects of one of them, to balance out their effects (such as with heroin and cocaine), or some people feel a combination actually enhances one or both of the substances. It is also known for users to attempt to reduce their dependence on one substance by gradually switching to another that might be seen as less harmful or addictive.
Different substances interact in hugely different ways in the body, from not at all to creating highly toxic and dangerous reactions. Certain substances have a long history of being used together, whilst others are newer and their full impact is not yet known.
Probably the most common polydrug use involves the use of alcohol and other substances, as many people do not think of alcohol as a ‘drug’. Alcohol can, however, have a big impact on the way many substances affect you. Some of the time this involves it enhancing the effects of the other drug, but with many substances alcohol can create a dangerous, potentially fatal, chemical reaction. It’s essential to check whether the substance you’re going to take is known to interact with alcohol. Look at the Harm Reduction sections of the A-Z drugs, and if in doubt it’s safest to avoid drinking when you’re taking something else.
- Cocaine and alcohol: alcohol can increase the levels of cocaine in the blood by about 30%. It also enables the production of a psychoactive cocaine metabolite (cocaethylene) with a longer duration in the blood. The combination of these two substances also increases heart rate and blood pressure, which could lead to a higher risk of heart attack. In addition, cocaine use can enhance alcohol’s intoxicating effects (i.e. make you feel even more drunk). Violent behaviour and suicidal ideation are not unknown with the use of these two substances.
- Opioids and cocaine: opioids (e.g. heroin) depress the central nervous system and cocaine stimulates it. The effects of cocaine on the heart are added to when used with opioids. Both cocaine and opioids can give breathing difficulties, which can be increased when used together. In addition, cocaine can initially mask the sedative (relaxing) effects of opioids, thereby increasing the risk of a later overdose.
- Opioids and benzodiazepines, with or without alcohol: opioids, benzodiazepines and alcohol are all depressants of the central nervous system. Their use together can lead to severe breathing difficulties. Older drug users may also face delayed metabolism of benzodiazepines (they take longer to break down) and there is an increased danger of breathing difficulties when used with methadone.
- Many of the newer ‘legal high’ and research chemical substances have not been thoroughly tested to see their effects in relation to each other and other substances. Be extremely cautious when mixing these drugs, and where possible avoid doing so, particularly if you’re unfamiliar with them.