The Actions of Interactions

Bad interactions from mixing prescriptions can occur not only when you are taking more than one drug – and not just literally at the same time – but also when you're taking medications as well as consuming alcohol or supplements. Miller says St. John's wort is one of the most common offenders. And the more drugs and supplements you add to your personal mix, the higher your risk of a dangerous effect climbs. Not all interactions are so blatant or their potential consequences life threatening. Nevertheless, if you want to get the greatest benefits of your medication with the least possible risks, all interactions bear watching.

Taking two or more medications can lead to a drug-drug interaction that can block the effect of one of the drugs you're taking – meaning it becomes ineffective and you don't get what you need – or it can cause too much of one drug to remain in your system or essentially produce an overdose. For example, if you take allopurinol (Lopurin or Zyloprim) for gout and add the immunosuppressive drug azathioprine (Imuran) to treat severe rheumatoid arthritis (RA), the azathioprine can further suppress your immune system, possibly putting you at risk of a serious infection. And both aspirin and the blood-thinning drug warfarin (Coumadin) decrease your blood's ability to clot, so if you're taking warfarin for cardiovascular disease and aspirin to ease arthritis pain, you could be unwittingly setting yourself up for a life-threatening bleeding episode.

Reducing the Risks

The FDA recently took an important step toward reducing the risk of drug interactions and other medication errors – at least in hospitals – by proposing a rule requiring bar codes on all medication packages. The mandate would require bar codes to include the National Drug Code (NDC), a system that contains the drug's name, dosage, form and strength. Bar code readers in hospitals would ensure that patients were getting the actual drug they were prescribed and could check for potential interactions between prescribed medications.

The FDA mandate is a step in the right direction, but the only way to completely eliminate the risk of mixing prescriptions is to completely eliminate your drugs –  hardly an option if you need medications to live and function. But there are ways you and your doctor can minimize the risk.