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Antibiotics Primer: How Long Does It Take to Work And Other Answers to Frequent Questions

Written on September 21, 2023 by Lori Mulligan, MPH. To give you technically accurate, evidence-based information, content published on the Everlywell blog is reviewed by credentialed professionals with expertise in medical and bioscience fields.

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Antibiotics are powerful, life-saving medications that treat bacterial infections. Learning when you need antibiotics and how to take them properly can help you benefit from these medications with the least risk and also help prevent antimicrobial resistance.

What Are Antibiotics?

Antibiotics are medications that fight bacterial infections. They don’t work against viral infections like colds or flu.

Bacteria are microscopic germs that live inside your body, on your skin, and all around you. Some types help keep you healthy. But certain bacteria can make you sick, with the effects ranging from mild to severe.

That’s why antibiotics are so important. They can help you feel better and are often lifesaving. But when it comes to antibiotics, it’s possible to have too much of a good thing. Using antibiotics when they’re not needed — like for viral infections or mild bacterial infections that would go away on their own — can lead to unnecessary side effects and contribute to the global problem of antibiotic resistance.

What Are the Benefits of Antibiotics?

Antibiotics have many benefits. They can:

  • Successfully clear bacterial infections from your body
  • Ease your symptoms and help you feel better
  • Speed up your recovery
  • Stop you from spreading an infection to others

What Conditions Do Antibiotics Treat?

Antibiotics treat a wide range of bacterial conditions that affect many different parts of your body, from your innermost organs to the outer surface of your skin. Below are some examples.

  • Skin and soft tissue infections
  • Infections in your throat and respiratory system
  • Infections in your urinary system and reproductive system
  • Eye infections
  • Other conditions, such as anthrax, endocarditis, Lyme disease, and sepsis due to a bacterial infection

How Do Antibiotics Work?

Antibiotics work by killing bacteria or stopping them from multiplying. Antibiotics can kill bacteria by destroying crucial parts they need to survive, like their cell walls or DNA. Antibiotics can stop the growth of bacteria by preventing them from making certain proteins they need to multiply.

How Long Does It Take For Antibiotics to Work?

It depends on the type of antibiotic you’re using and what it’s treating. You need to take a full course of antibiotics exactly as your provider prescribes it. You may start to feel better in just a few days, but you should still take the rest of the medicine.

Don’t save any of your antibiotics for a later time. This isn’t safe and won’t help you in the future. You should only use antibiotics to treat the specific infection you received them for.

How Long Do Antibiotics Stay In Your System?

Antibiotics typically stay in your system anywhere from a few hours to several days after you stop taking them. Many factors (including the type of antibiotic you’re taking, its dosage, and your age) can affect the amount of time the drug stays in your system.

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When Should You Not Use Antibiotics?

You shouldn’t take antibiotics for viral infections. Antibiotics target bacteria, not viruses. So, they won’t work against conditions like:

  • The flu
  • A common cold or runny nose
  • Most instances of bronchitis
  • A sore throat (unless it’s strep throat)
  • A sinus infection caused by a virus

You likely don’t need antibiotics for some bacterial infections that typically go away on their own. These include:

  • Some sinus infections caused by bacteria
  • Some ear infections

What Are the Possible Side Effects of Antibiotics?

Common (and usually mild) side effects of taking antibiotics include:

  • Diarrhea
  • Nausea and vomiting
  • Dizziness
  • Rash
  • Yeast infections

Serious side effects, which are less common, include:

  • C. diff infection
  • Allergic reactions

Be sure to read the instructions and warnings that come with your antibiotics. Learn all possible side effects and the signs of an allergic reaction. Contact your provider if you have any questions or concerns. [1]

What Are Resistant Bacteria?

Each time you take an antibiotic, bacteria are killed. Sometimes, bacteria causing infections are already resistant to prescribed antibiotics. Bacteria may also become resistant during the treatment of an infection. Resistant bacteria do not respond to the antibiotics and continue to cause infection. A common misconception is that a person's body becomes resistant to specific medicines. However, it is the bacteria, not people, that become resistant to the medicines.

Each time you take or give your child an antibiotic unnecessarily or improperly, you increase the chance of developing medicine-resistant bacteria. Therefore, it is critically important to take antibiotics only when necessary. Because of these resistant bacteria, some diseases that used to be easy to treat are now becoming nearly impossible to treat.

Bacteria can develop resistance to certain medicines [2]:

  • Medicine resistance happens when bacteria develop ways to survive the use of medicines meant to kill or weaken them.
  • If a germ becomes resistant to many medicines, treating the infections can become difficult or even impossible.
  • Someone with an infection that is resistant to a certain medicine can pass that resistant infection to another person.

Why Is It Important To Take Antibiotics Only When They’re Needed?

Anytime antibiotics are used, they can cause side effects and contribute to antibiotic resistance, one of the most urgent threats to the public’s health.

Too many antibiotics are prescribed unnecessarily and misused, which threatens the usefulness of these important drugs.

This is why it’s important that we all use antibiotics ONLY when we need them to protect us from harm caused by unnecessary antibiotic use and to combat antibiotic resistance.[3]

What Does Everlywell Offer In Relation To Antibiotic Treatment?

Everlywell offers UTI treatments and UTI antibiotics online. UTI symptoms for people assigned female at birth can include pain while urinating or a persistent urge to urinate that doesn’t go away. A telehealth visit may be right for you if you are female and have mild UTI symptoms.

Book a video appointment with a clinician who can diagnose your condition based on symptoms and prescribe medication, if appropriate. Get prescriptions sent directly to your pharmacy. (Age 18+)

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  1. Antibiotics: What to Know. Cleveland Clinic. Last reviewed on 5/24/2023.https://my.clevelandclinic.org/health/drugs/16386-antibiotics. Accessed on 9/9/2023.
  2. Antibiotics. Johns Hopkins Medicine. https://www.hopkinsmedicine.org/health/wellness-and-prevention/antibiotics. Accessed on 9/13/2023.
  3. Antibiotic use Q & A. CDC. https://www.cdc.gov/antibiotic-use/q-a.html. Accessed on 9/13/2023.
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