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Mixing Drugs: A Guide to Safe Combinations and Harm Reduction

When you combine drugs, no matter what type of drugs they are, there is a likelihood that the drugs will have some sort of interaction with one another.

In some cases, the interaction is mild and relatively harmless. In other cases, though, the interaction can lead to a deadly overdose.

If you are mixing drugs for medical or recreational purposes, it is important to be aware of the potential side effects you might experience.

drug effects

How Drugs Affect Each Other

Some drugs can decrease the effectiveness of other drugs, which can be harmful if you are taking the drugs for medical reasons. Other drugs can increase the effects of each other. Consuming alcohol while taking other recreational drugs, for example, is a commonly reported practice by people who are hoping to increase the intoxicating effects experienced.

Drug interactions are likely to be caused when two or more drugs are taken at the same time. The more drugs you take, the greater your chances are for experiencing complications with interactions. While some interactions can be anticipated, most interactions are highly unpredictable and can lead to serious complications.

As multiple drugs are put into the body at once, it can change how the body metabolizes the substances. It also puts added stress on the liver, which is the organ primarily responsible for processing substances.

Specific enzymes are also activated for the metabolization of certain substances. Different drugs can activate different enzymes, resulting in an imbalance of enzyme activity that is needed to monitor the concentration of drugs in the body.

Can Any Classes of Drug Be Safely Mixed?

benzodiazephine overdose

Drugs can be classified in many different ways, such as by the active ingredient they contain, how they are used, the condition they aim to treat, or how they have been scheduled by the DEA. It is also possible for drugs to be classified in more way than one.

Regarding substance abuse and addiction treatment, the most commonly used drug classifications are:

  • Depressants, such as alcohol, barbiturates, and benzodiazepines.
  • Stimulants, such as cocaine, Adderall, methamphetamine, and caffeine.
  • Opioids, such as morphine, oxycodone, fentanyl, and heroin.
  • Cannabinoids, such as marijuana and hashish.
  • Hallucinogens, such as LSD, PCP, and mushrooms.
  • Inhalants, such as paint thinner, aerosol sprays, gasoline, and glue.

For the most part, recreational drugs cannot be safely mixed with one another. When taken in unknown quantities and from unknown sources, it is very difficult to predict what side effects will be experienced and to what degree. When using drugs for medical purposes, doctors with a knowledge of the specific interactions of the drugs they prescribe may be able to recommend relatively safe combinations of drugs, though side effects are still expected to occur.

Classes of Drugs to Avoid Mixing

One of the most important drug combinations to avoid is combining drugs from the same class. When two drugs from the same class are mixed together, their effects are greatly enhanced, as are the dangers. Opioids used in conjunction with other opioids, for example, have greatly contributed to the opioid overdose epidemic and the number of fatal overdoses that are occurring.

Classes of drugs to avoid mixing, as well as their possible side effects, include:

  • Opioid intoxication can dramatically suppress breathing, even to the point of death.
  • High levels of stimulants in the body can cause anxiety, panic attacks, psychosis, heart problems, and serotonin syndrome.
  • Combining central nervous system depressants can slow vital bodily functions, such as breathing and heart rate, to the point of death.
  • Stimulants and depressants. Combining these opposing types of drugs can lead to heart problems, dehydration, overheating, kidney failure, respiratory infections, and bronchitis.

While the general interactions between different classes of drugs can be anticipated, everyone responds to drugs differently, so the exact interactions of drugs cannot be predicted for every individual. What is known is that mixing drugs together, no matter what class they belong to, greatly increases your risk of overdose and experiencing dangerous medical complications.

Mixing Alcohol with Drugs

Alcohol is such a widely consumed substance that its harmful effects, especially when consumed with other substances, is often underestimated. The National Institute on Alcohol Abuse and Alcoholism (NIAAA) warns that mixing alcohol with prescription and over-the-counter medications can be very harmful. It is not advised to mix alcohol with any type of recreational or medical drug.


Common side effects are observed when mixing alcohol with medicines.

  • Drowsiness
  • Dizziness
  • Increased risk of overdose
  • Fast or irregular heartbeat
  • Sudden changes in blood pressure
  • Fainting
  • Slowed or difficulty breathing
  • Impaired cognition
  • Altered motor control
  • Unusual behavior
  • Memory problems
  • Liver damage
  • Stomach bleeding
  • Stroke
  • Ulcers
  • Heart attack
  • Changes in mood

It is particularly dangerous to mix alcohol with medications that can cause drowsiness or sleepiness. Alcohol is likely to enhance these effects and make it unsafe to drive or operate heavy machinery. People are sometimes unaware of how alcohol impacts them when they are taking medications and find themselves in dangerous situations, such as operating a vehicle under the influence, after having drank less alcohol than would normally cause such impairment.

The Dangers of Polydrug Abuse

The dangers of polydrug abuse lie in the unknown outcomes that can occur when combining multiple drugs at once. People reportedly engage in polydrug use with an intention of enhancing particular aspects of a high. The effects you experience through polydrug use, however, cannot be controlled and are very unpredictable.

Some polydrug use is done with the intention of achieving a particular high while other use is random and occurs when whatever drugs are available are consumed. Either way, mixing drugs together greatly increases your chances of experiencing a drug overdose. According to the National Institute on Drug Abuse (NIDA), the rates of overdose deaths across the U.S. have increased steeply over the last two decades.

In 1999, 16,849 deaths were attributed to drug overdoses. By 2017, that number increased to 70,327. Additionally, the number of fatal overdoses from prescription opioids used in combination with other narcotics has increased steadily since 2014. Overdoses related to fentanyl abuse, which is most frequently mixed with other substances, exhibited the sharpest increase in overdose deaths from 2014 to 2017, with a total of 28,400 fatal overdoses in 2017.

If you are experimenting with polydrug use, it is important to know the signs of a drug overdose so you can medical help right away. An overdose caused by polydrug use may be intentional or accidental. Either way, life-threatening symptoms must be addressed right away.

A severe overdose can causes someone to stop breathing and experience damage to vital organs. Receiving immediate medical intervention can increase one’s chances of survival as well as minimize the harmful effects of an overdose.

Methods of Harm Reduction

woman sitting from drug use

Although abstaining from all recreational drug use is your best way to reduce your risk of experiencing harmful side effects, that is not realistic for everyone. For people who intend to continue using drugs recreationally, there are things you can do to reduce your risk of experiencing negative side effects.

Methods of harm reduction regarding drug use include:

  • Only use one substance at a time, including alcohol.
  • Have a buddy close by whenever you do use drugs who will be able to assist you in the event of a medical emergency.
  • Only use drugs in a safe environment that you are familiar with.
  • Only use clean needles, and never share needles.
  • Keep naloxone on hand, if opioid overdose is a risk.
  • Keep yourself informed about signs of an overdose and what to do in the event of an emergency.

Harm reduction does not eliminate your chances of experiencing harmful events due to recreational drug use, but it can greatly reduce the likelihood of encountering such complications. Implementing methods of harm reduction is your best technique for ensuring safe drug use.

When Is It Safe to Mix Drugs?

There are times when doctors may recommend mixing certain medications. When a specific drug interaction is known to only increase the intended benefits of a drug without increasing the risk of negative side effects, it may be safe and recommended to combine medications.

You should never attempt to mix medications on your own, however, as it is very difficult to anticipate the side effects. Only mix drugs at your doctor’s recommendation to ensure it is safe and you are unlikely to experience harmful effects.


Drug Classes. (2019).

Drug Interaction Checker. (2018). RxList.

Harmful Interactions: Mixing Alcohol with Medicines. (2014). National Institute on Alcohol Abuse and Alcoholism.

Overdose. (January 2017). U.S. National Library of Medicine: Medline Plus.

Overdose Death Rates. (January 2019). National Institute on Drug Abuse.

Polydrug Use: Factsheet. (2019). Positive Choices.

The Dangers of Mixing Drugs. The Government of South Australia.

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