Of the almost 2.5 million emergency department (ED) visits related to drug abuse or misuse in 2011, the Drug Abuse Warning Network (DAWN) reported that more than a third involved multiple substances. Drugs and alcohol affect multiple bodily systems, including the central nervous system and brain, which are responsible for sustaining life. Any form of drug or alcohol abuse can be dangerous and run the risk of an adverse reaction, but mixing substances only compounds the risks. Abuse of more than one drug at a time is called polydrug abuse.

The Centers for Disease Control and Prevention (CDC) reported that in 2014, approximately 47,055 Americans died from a drug overdose. Mixing more than one mind-altering substance can be catastrophic and increase the risk for overdose. In addition to enhancing the negative effects of each drug used, different types of substances can react negatively with each other.

There are several different classifications of drugs that act on the body in specific ways. Common drug types are:

  • Central nervous system depressants: These include benzodiazepines and alcohol, which slow down nerve firings in the brain. This in turn lowers heart rate, blood pressure, respiration, and temperature while decreasing anxiety and enhancing the ability to sleep.
  • Narcotic analgesics: Opioid drugs like heroin and prescription pain killers slow respiration while blocking pain sensations and causing relaxation.
  • Stimulants: Examples include cocaine, methamphetamine, and prescription ADHD medications. These drugs speed up heart rate, blood pressure, and body temperature, and increase energy and focus.
  • Hallucinogens: These include LSD, magic mushrooms, and ketamine. These drugs alter perceptions and distort reality.
  • Inhalants: These volatile substances are often common household objects that are huffed, sniffed, or inhaled to produce a mind-altering effect. These products may have a variety of unpredictable interactions in the body.
  • Other: Some drugs have multiple effects on the body and therefore do not fit squarely into the prior categories. Marijuana is both a hallucinogen and a central nervous system depressant, while ecstasy (MDMA) has both psychedelic and stimulant properties

Mixing certain types of drugs can be especially dangerous. Highlighted here are some common drug combinations and the potential risk factors involved in taking both at once.

Benzodiazepines and Alcohol


Man Shows Willpower Not To Drink Alcohol

Alcohol is legal, cheap, socially acceptable, and one of the most commonly used psychoactive substances with addictive properties. Close to 1 in every 12 American adults aged 12 and older battles an alcohol abuse or dependence issue, the National Council on Alcoholism and Drug Dependence (NCAAD) reports.

Many people don’t consider alcohol to be in the same category as drugs. Therefore, they do not consider it to be a dangerous substance; hence, it is regularly used in combination with other drugs. The DAWN report of 2011 published that there were 600,000 ED visits involving drugs and alcohol combined, which is about a quarter of the overall ED visits related to the abuse or misuse of drugs in general. A little over 20 percent of the ED visits related to alcohol combined with a pharmaceutical drug involved benzodiazepines.

Mixing alcohol with benzodiazepine drugs, which are sedatives and tranquilizers often prescribed for the relief of insomnia or anxiety, can amplify the effects of both of these substances since they are both central nervous system depressants. Benzodiazepines, often called benzos, include Valium (diazepam), Xanax (alprazolam), Klonopin (clonazepam), and Ativan (lorazepam), which are some of the most prescribed psychiatric drugs in American, Psych Central reports.

The U.S. Food and Drug Administration (FDA) issues warnings in the prescription information and on labels of benzodiazepine prescription medications about the dangers of mixing these drugs with substances, including alcohol, as the combination can increase sedation levels. This can make it harder to breath, slow down pulse and heart rate, lower body temperature, and cause extremely low blood pressure. The National Institute on Drug Abuse (NIDA) publishes that in 2014 there were around 8,000 overdose deaths involving a benzodiazepine drug. The CDC reported that in 2010, alcohol was involved in more than 20 percent of the benzodiazepine overdose fatalities.

Both alcohol and benzos can also reduce inhibitions, possibly making people more sociable and mellow, and potentially increasing the odds for being involved in a situation that may become dangerous or risky as decision-making abilities are also impaired. Accidents, injuries, and questionable sexual encounters may be more prevalent when benzos and alcohol are mixed. The rate of developing a dependence on benzodiazepine drugs and/or alcohol also increases when these drugs are regularly combined.

Alcohol and Opioids

Just as benzodiazepines are commonly mixed with alcohol, so are opioid drugs. The CDC reported that in 2010, alcohol was involved in 18.5 percent of ED visits related to the misuse of prescription opioids, and alcohol was also present in 22.1 percent of prescription opioid deaths. Opioids are not generally classified in the same category as central nervous system depressants; however, they do function to lower the same vital life functions that these substances, including alcohol, do.

NIDA reports that adolescents are commonly mixing prescription opioids with other substances. In fact, those who abuse these drugs are more than four times as likely to admit to being drunk more than 10 times. In addition, more than half of teens abusing prescription painkillers mix them with alcohol. This increases the odds for a negative interaction, potentially leading to a life-threatening overdose when breathing rates are lowered too far causing respiratory failure. The CDC publishes that 44 people die in the United States every day as the result of a prescription opioid overdose.

Heroin and Cocaine

Heroin abuse seems to be on the rise in the United States, perhaps due in part to stricter regulations on prescription opioid painkillers. Newsweek reports that heroin and opioid drug overdoses accounted for 61 percent of the total overdose fatalities in 2014; there were four times as many opioid overdose deaths in 2014 than in the year 2000.

Heroin is an opioid drug that produces an intense and rapid-onset high, while it lowers anxiety, blood pressure, heart rate, and respiration levels. Cocaine, on the other hand, is a stimulant drug. It also produces a rapid burst of euphoria, increasing energy levels and excitement, and decreasing the need for sleep.

Cocaine and heroin may be mixed together into what is termed a speedball. The high is particularly intense, and users believe that the negative effects of each drug may be reduced by combining them in this way. The truth is that mixing cocaine and heroin compounds the effects of both. Since one drug depresses the central nervous system and the other stimulates it, it may be difficult to know when too much of either is taken and be harder to recognize potentially dangerous symptoms however.

Speedballing is often done by injecting both heroin and cocaine together. This not only increases the potential side effects of either drug, it can also increase the risk for overdose, the possibility of contracting an infectious disease like HIV/AIDS or hepatitis due to injection drug abuse, and make drug abuse treatment more complicated, NIDA reports.

Cocaine typically wears off faster than heroin does, so once the stimulant portion of the combination leaves the body, the depressant effects of heroin are all that’s left, possibly resulting in difficulty breathing and dangerously low respiration levels.
Mixing Prescription Opioids and Benzos

Prescription drugs are mistakenly considered to be “safe” alternatives to illicit drugs since they may initially come from a doctor. These drugs are meant to be used exactly as prescribed, however, and any use outside of a legitimate prescription is considered abuse.

Prescription drug abuse is rampant in the United States, with 52 million Americans (aged 12 and older) admitting to some form of prescription drug misuse in their lifetimes, NIDA reports. Different prescription drugs are commonly abused simultaneously for a variety of desired effects.

A common combination is benzodiazepines and opioids, possibly for the potential for an increased high when they are mixed. A study published in the journal Drug and Alcohol Dependence showed that between 40 and 60 percent of individuals suffering from chronic pain, and therefore regularly taking prescription opioids, may also use benzos at the same time. Taking both drugs at once raises the risk for a potentially fatal overdose as well as the likelihood of a more serious ED visit outcome than taking each drug independently, the DAWN Report states. The CDC reports that both ED visits and overdose fatalities commonly involve a combination of prescription benzodiazepine and opioid drugs.

Other Dangerous Drug Combinations

Mixing any two psychoactive substances can be potentially dangerous, as it can increase the possible side effects of both substances and may more rapidly result in a toxic buildup in the body, or an overdose. The drugs’ interaction in the brain can also increase the rate of dependency, thus amplifying potential withdrawal symptoms and leading to addiction more quickly than abusing one substance on its own may.

Marijuana is one of the most commonly abused illegal and mind-altering substances in the United States by adolescents, according to NIDA, who commonly mix the drug with prescription opioids. NIDA reports close to 60 percent of teenagers abusing prescription pain relievers do so in combination with marijuana. When abused, both drugs have the potential for impairing a person’s decisions and cognitive abilities, and may increase the odds for participating in activities that may be dangerous or risky.

Club drugs, which are often synthetic, psychoactive substances typically taken at all-night dance parties or raves, are also often mixed with other drugs or alcohol. DAWN reported that alcohol was present in 72 percent of ED visits involving the drug ketamine, a dissociative and hallucinogenic drug often classified as a club drug. Mixing alcohol with club drugs, stimulants, or even over-the-counter cold or cough medications can lead to heart problems, stroke, convulsions, or difficulties breathing, NIDA Teen warns.

Stimulants like cocaine or prescription ADHD medications may be abused in tandem with central nervous system depressants like alcohol, benzos, or opioids to attempt to counteract the negative side effects of each drug. Unfortunately, this can actually backfire and lead to a higher risk of overdose and increased risk for drug dependence. When someone regularly abuses more than one drug at a time, this can interfere with the treatment for substance abuse or mental illness as well.

All drugs can be dangerous when abused on their own, but when mixed with other substances, the risks increase exponentially. Specialized treatment is required in cases of polydrug abuse.