Despite warning labels on prescription pill bottles and frequent news reports of celebrity overdoses, people are not taking the risks of fatal drug combinations seriously. Prescription drugs and alcohol are legal, so they must be safe, right? Few people even consider them drugs, yet together they are responsible for thousands of preventable deaths each year.

While alcohol and prescription drugs are among the most common and dangerous, other types of interactions also can be life-threatening, including interactions between herbal or dietary supplements, illegal drugs, over-the-counter medications, and even some foods.

Certain medications have a similar function and can increase each others effects, risking severe side effects or overdose, whereas others decrease or block another drugs effects, causing one or both drugs not to work as intended.

Dangerous drug combinations are of particular concern among adults ages 50 and older, who are more likely to take a variety of medications for different ailments and whose bodies are more sensitive to the drugs effects. Given that more than half of older adults take five or more prescription drugs, over-the-counter medications or dietary supplements every day, the risk of an adverse drug interaction is high.

Although there are dozens of drug combinations that pose risks, here are seven of the most significant threats to guard against:

#1 Benzodiazepines and Alcohol

Consider this common scenario: A person looking for relief from distress drinks alcohol, then takes a benzodiazepine (such as Xanax, Klonipin, Valium or Ativan) because they want to fall asleep. Because the medication isnt absorbed quickly enough, which delays relief, the person drinks more. Another typical situation is for an individual to forget how much of a prescription medication they have taken because their memory is impaired by alcohol.

The danger here is that both alcohol and benzodiazepines work as depressants in the bodys central nervous system and increase sedation. This can lead to dizziness, confusion, impaired memory, increased irritability and aggression, loss of consciousness and coma. Alone, benzodiazepines pose little risk of overdose, but when mixed with alcohol the combination can be potentially lethal.

#2 Opiates and Alcohol

Another class of drugs frequently combined with alcohol is opiates, such as heroin, morphine, codeine, OxyContin and Vicodin. In many cases, the individual takes an opiate painkiller to manage pain from an accident or injury and finds greater relief (and even a sense of euphoria) when supplementing with alcohol. Combining these drugs enhances the sedative effects of both substances, increasing the risk of respiratory depression and overdose.

#3 Antidepressants and Alcohol

Alcoholism and depression are common co-occurring disorders, which puts individuals at high risk for interactions between alcohol and antidepressant medications such as Prozac and Elavil. Effects can include impaired thinking, dangerously high blood pressure, intensified depression symptoms and death.

Certain antidepressants may also interact with MAOIs, causing dizziness, seizures, confusion and coma and putting users at risk of serotonin syndrome, a potentially life-threatening condition. Other medications and supplements that may interact with certain antidepressants are prescription painkillers, the herbal remedy St. Johns wort, the bronchodilator albuterol and some over-the-counter antihistamines.

#4 Stimulants and Alcohol

Stimulants such as Ritalin, Adderall, meth, speed and cocaine mask the effects of alcohol, which can cause users to drink more than they intended. This can lead to increased blood pressure and tension as well as overdose when alcohol and cocaine are mixed. Since the stimulant drug class also includes caffeine, nicotine, diet pills, and certain over-the-counter cold remedies and decongestants, it can be dangerous to use these products when drinking (especially if driving).

#5 Warfarin and Aspirin

Combining the blood thinner warfarin (Coumadin) with aspirin can significantly increase the risk of bleeding. The risk is even higher when taken with garlic pills or leafy, green vegetables such as spinach, broccoli, cabbage or Brussels sprouts.

#6 Lisinopril and Potassium

Combining this blood pressure drug (also known as Zestril or Prinivil) with potassium can cause irregular heart rhythms or death. Potassium and potassium-rich foods may be recommended for those on certain blood pressure and heart rhythm medications, while foods like black licorice and certain herbals teas and sweeteners may lower potassium levels, putting patients hearts at risk. Certain over-the-counter decongestants may also be problematic as they can decrease the effectiveness of blood pressure medications.

#7 Statins and Niacin

The combination of popular prescription cholesterol drugs (statins) and over-the-counter niacin (a type of B vitamin that lowers cholesterol) can increase the risk of muscle pain and damage. Statins can also be dangerous when combined with prescription oral fungal/yeast infection medications because of the impact on the kidneys, as well as grapefruit juice, which increases the risk of liver and kidney damage and the breakdown of muscle cells.

Protecting Against Adverse Drug Interactions

Mixing drugs always presents some danger, though the degree of risk depends on a number of factors, including the type of drugs and amount used and the patients medical condition. The best protection is not to mix drugs, though in some cases this is unavoidable. In these cases, patients should take the following precautions:

Know what drugs you are taking, why, what their side effects include and if any special precautions are needed.

Obtain all prescription medications through the same pharmacy so that there is a record of the medications you are taking.

Tell your doctor and pharmacist about any over-the-counter, herbal or illegal substances you are taking and ask about possible interactions.

Dont take a medication prescribed for someone else.

Talk to your doctor before increasing the dosage of a medication or using a medication other than as prescribed.

Adverse drug interactions are one of the leading causes of death in the U.S. Americans are quick to take medications from doctors who are quick to prescribe them (studies show most patients walk out of their doctors office with an average of two prescriptions per visit), often without weighing the risks and benefits. Those who are going to take medication must do so responsibly in order to minimize the risk of a deadly drug combination.

Pills and alcohol photo available from Shutterstock.