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Why you should never take leftover antibiotics

A pair of hands holding pills and a pill bottle.

Where's the harm? Leftover antibiotics are no good for anyone.

Dec. 6, 2019—You've got the sniffles, a sore throat and a cough that won't go away. You're just about ready to call the doctor. But wait—don't you have some leftover antibiotics from your last illness? Why not try those first?

It's a common temptation. In fact, nearly 1 in 5 adults ages 50 to 80 said in a recent poll that they've taken leftover antibiotics. But if a nagging voice inside your head says, "Hold off!" you'd be wise to listen to it.

What's so wrong with using leftovers?

In the first place, there shouldn't be any. Antibiotics work by killing off the bacteria that are making you sick—or by stopping them from reproducing. But that doesn't happen all at once. Some bacteria are better than others at resisting the medicine. That's why your doctor will tell you to keep taking your antibiotics until they're all gone—even if you start to feel better. You need to take every last pill in order to make sure all the bacteria are gone for good.

If you stop too soon, the toughest germs to kill have a chance to make a comeback—and pass along that toughness to the next generation.

That's also the reason you shouldn't take leftovers. You need the full course to get the full benefit.

What's more, you may need a different antibiotic, a different dose or a different medicine altogether for your particular illness. Without medical advice, you risk potentially dangerous interactions with any other drugs you might take.

What else can go wrong?

Used the right way, antibiotics can destroy germs that make us sick. They can even save lives. But when they're overused, that can cause problems for everyone.

Antibiotics don't work against viruses, such as the ones that cause colds, the flu and bronchitis. They only fight bacteria.

Using antibiotics when they're not appropriate fuels antibiotic resistance. That's what happens when bacteria become immune to the antibiotics designed to kill them. And it's happening more and more often.

More than 2.8 million people in the U.S. get sick every year because of antibiotic-resistant bacteria, the Centers for Disease Control and Prevention reports. Worse, someone dies from a resistant infection every 15 minutes in the U.S.

What you can do

When you or your loved one is sick, get a doctor's advice before taking any leftover medicine. That simple step can keep you—and everyone else—safer. And it can help make sure that antibiotics still work when we really need them.

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