Prescribed an antibiotic? Here’s what you need to know.

July 2022

When the first antibiotic — penicillin — made its way into standard medical treatment, it was a major medical breakthrough. For the first time, doctors could treat infections that might have once been debilitating or fatal.

Doctors still use antibiotics today to treat certain types of infections. Learn more about what infections antibiotics can — and can’t — treat, as well as how they work and potential side effects.

What are antibiotics, and how do they work?

Antibiotics are any type of medication used to treat bacterial infections. They can work in one of two ways:

  • They can kill the bacteria that are causing the infection.
  • They can stop the bacteria from reproducing.

What diseases can antibiotics treat?

Antibiotics can be used to treat a variety of bacterial infections. This can include the following:

How are antibiotics given?

Antibiotics may be given in a variety of ways. They may be in the form of:

  • Pills (capsules, tablets, etc.)
  • Liquids (for younger kids and people who experience trouble swallowing pills)
  • Drops (for ear infections)
  • Topical creams (for minor skin infections)
  • Intravenous (IV). IV antibiotics are generally reserved for people with deep-seated or life-threatening infections, people who can’t absorb or keep oral medication down, and immunocompromised people (who have a harder time fighting infection).

What are the side effects of antibiotics?

Antibiotics are not without side effects, but the benefits generally outweigh the risks. The most common side effects are those of the GI tract, such as nausea, upset stomach, vomiting, and diarrhea. Other common side effects include skin rashes and secondary infections of the digestive tract (such as C. diff.), the vagina (such as yeast infections), and the mouth (thrush).

Other, less common side effects vary based on the specific antibiotic your doctor prescribes. Be sure to tell your doctor and pharmacist about all other medications you take and any underlying medical conditions you have. And be sure to read — or have your pharmacist walk you through — any potential side effects from the antibiotic you’re prescribed.

Why antibiotics aren’t always the answer

Sometimes you may think you need an antibiotic, but your provider doesn’t prescribe one. That’s because antibiotics only work if your illness or infection is due to bacteria. If a virus or other pathogen is causing your problem, an antibiotic won’t help.

In addition to causing unnecessary side effects, taking antibiotics when they’re not needed increases the chances of the bacteria developing antibiotic resistance. That’s when the bacteria mutate and evolve to evade the killing or growth-inhibiting properties of the antibiotics.

The more an antibiotic is used, the likelier it is that some bacteria will eventually adapt and become resistant to it. That’s why doctors aim to give patients antibiotics only when necessary.

Taking antibiotics as prescribed

Be sure to take any antibiotics as prescribed. You will often feel better before your prescription runs out, because your symptoms will likely end before your supply of pills does. That’s because you’ll likely feel better once the amount of bacteria in your body is reduced. But it doesn’t necessarily mean that your infection is truly gone.

By taking your medication as prescribed, you reduce the chance that your infection will come back. You also reduce the chances of those bacteria becoming resistant to the antibiotics you were prescribed.

If you have any questions or concerns regarding your prescribed antibiotic, your pharmacist can help.

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