What Are Antibiotics?

Antibiotics are medicines that help stop infections caused by bacteria. They do this by killing the bacteria or by keeping them from copying themselves or reproducing.

The word antibiotic means “against life.” Any drug that kills germs in your body is technically an antibiotic. But most people use the term when they’re talking about medicine that is meant to kill bacteria.

Before scientists first discovered antibiotics in the 1920s, many people died from minor bacterial infections, like strep throat. Surgery was riskier, too. But after antibiotics became available in the 1940s, life expectancy increased, surgeries got safer, and people could survive what used to be deadly infections.

What Antibiotics Can and Can’t Do

Most bacteria that live in your body are harmless. Some are even helpful. Still, bacteria can infect almost any organ. Fortunately, antibiotics can usually help.

These are the types of infections that can be treated with antibiotics:

Only bacterial infections can be killed with antibiotics. The common cold, flu, most coughs, some bronchitis infections, most sore throats, and the stomach flu are all caused by viruses. Antibiotics won’t work to treat them. Your doctor will tell you either to wait these illnesses out or prescribe antiviral drugs to help you get rid of them.

It’s not always obvious whether an infection is viral or bacterial. Sometimes your doctor will do tests before deciding which treatment you need.

Some antibiotics work on many different kinds of bacteria. They’re called “broad-spectrum.” Others target specific bacteria only. They’re known as “narrow-spectrum.”

Side Effects

Since your gut is full of bacteria -- both good and bad -- antibiotics often affect your digestive system while they’re treating an infection. Common side effects include:

Occasionally, you may have other symptoms, like:

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These symptoms can mean you’re allergic to your antibiotic, so let your doctor know right away if you have them.

If you’re taking birth control pills, antibiotics may keep them from working as well as they should, so speak to your doctor about whether alternative birth control methods might be a good idea. Women can also get vaginal yeast infections while taking antibiotics. The swelling from it causes itching, burning, vaginal discharge (looks similar to cottage cheese) and pain during sex. It's treated with an anti-fungal cream.

Antibiotic Resistance

Antibiotics are a powerful germ-fighting tool when used carefully and safely. But up to one-half of all antibiotic use isn’t necessary. Overuse has led to antibacterial resistance. Bacteria adapt over time and become “super bacteria” or “superbugs.” They change so that antibiotics no longer work on them. They pose a big threat, because there aren’t any medicines to kill them.

The best way to help slow the spread of super bacteria is by being smart with antibiotics. Here’s how:

  • Trust your doctor if she says you don’t need them.
  • Don’t take them for a viral infection.
  • Only take the ones your doctor has prescribed for you.
  • Take them as directed.
  • Don’t skip doses.
  • Take them for the full number of days your doctor prescribes.
  • Don’t save them for later.
WebMD Medical Reference Reviewed by Sabrina Felson, MD on February 05, 2017

Sources

SOURCES:

American Academy of Pediatrics: “The History of Antibiotics.”

Association for Professionals in Infection Control and Epidemiology: “Antibiotic Safety.”

NHS Choices: “Antibiotics.”

Alliance for the Prudent Use of Antibiotics: “When and How to Take Antibiotics.”

CDC: “Antibiotics Aren’t Always the Answer.”

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