How Coffee Messes With Meds

By Dirk Hanson 12/07/11

All manner of prescribed drugs are apparently incompatible with a cup of Joe.

The consequences can go beyond the mere
effect of caffeine.
Photo via

Now that you’ve gotten used to the idea that grapefruit sometimes interacts badly with prescription meds, here's even worse news: coffee can screw up certain prescribed drugs too. Your three cups of morning brew can interfere with the absorption of oral medications, primarily by "competing" for an enzyme that metabolizes drugs. Sometimes, even taking your medication with a single cup of coffee is a bad idea. The New York Times reports that antidepressants, thyroid, and osteoporosis meds are common culprits. For example, the antidepressant Luvox slows the breakdown of caffeine, increasing the likelihood of jitters. And Premarin—taken by women for bone loss and menopausal symptoms—also competes with caffeine metabolization, raising the chances of headache, rapid heartbeat, sweating and more. The antibacterial drug Cipro, certain MAOI antidepressants and common asthma drugs may do the same. Caffeine and other coffee compounds can also combine with metabolizing enzymes, interfering with the absorption of drugs and making them less potent. Drinking black coffee with the osteoporosis drug Fosamax cuts effective absorption by more than half, and reduces the effectiveness of thyroid drugs by almost as much. Finally, as we all know, caffeine is a stimulant: when you combine it with other stimulants like ephedrine, Adderall or cocaine, it sometimes causes heart problems. So while coffee itself may not ruin your health, its effects on the other drugs you take just might.

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Dirk Hanson, MA, is a freelance science writer and the author of The Chemical Carousel: What Science Tells Us About Beating Addiction. He is also the author of The New Alchemists: Silicon Valley and the Microelectronics Revolution. He has worked as a business and science reporter for numerous magazines and trade publications including Wired, Scientific American, The Dana Foundation and more. He currently edits the Addiction Inbox blog. Email: [email protected]