Wellness Mind & Body When Do You Need Antibiotics? How long you've been sick and the presence of a sore throat are a few factors that might determine the need for this treatment. By Amanda Gardner Updated on April 30, 2023 Medically reviewed by Femi Aremu, PharmD Medically reviewed by Femi Aremu, PharmD Femi Aremu, PharmD, is a Drug Information Pharmacist for Red Ventures and practiced in a COVID-19 clinic for the University of Chicago Medicine. learn more Share this page on Facebook Share this page on Twitter Share this page on Pinterest Email this page One type of medicine that helps people get better when they're sick is antibiotics. Antibiotics are a treatment option when you have certain types of bacterial infections. However, more goes into using antibiotics for treatment, such as when to take them, what they treat, and their side effects. Read on to learn more. Viral vs. Bacterial Pneumonia: What's Really the Difference? What Are Antibiotics? Antibiotics are a medicine designed to kill bacteria or make bacterial growth difficult. For example, they may break the cell wall that protects the bacteria. They could also damage the bacteria's DNA so the bacteria can't repair themselves and continue growing. The most common dosage forms for antibiotics are: Oral: Pills, capsules, or liquids taken by mouthTopical: Creams, sprays, or ointments applied to the skin; ointment or drops for the eyes; or drops for the earsInjectable: Injections or intravenous (IV) infusions, typically given when infections are serious The medicines are bacteria-based, mold-based, or made from scratch. When Are Antibiotics Necessary? Antibiotics help treat some bacterial infections, such as: E. coli infections Pneumonia Sepsis Strep throat Urinary tract infections (UTIs) Whooping cough In some cases, antibiotics may not be enough to handle bacterial infections. Some infections may need other treatments, like surgery, along with antibiotics. Every bacterial infection doesn’t require antibiotics. For example, sinus and middle ear infections will often clear up on their own. Also, viruses are responsible for most sinus infections, meaning that antibiotics wouldn't be helpful. Antibiotics for middle ear infections may only be necessary in severe cases. What Else Determines Antibiotic Use? Healthcare providers will do lab tests to help them diagnose infections when you are sick. The test results will help them determine if a bacterial infection is present and how to prescribe medication, including antibiotics. However, if a healthcare provider believes you have an infection that requires antibiotics, they may go ahead and prescribe them. The provider might change the prescribed antibiotic later depending on treatment results. The following symptoms may help them determine what antibiotics—if any—are necessary to treat your illness: Fever: If you have a fever, shakes, and chills, you could have a bacterial infection. However, those are also common with viral illnesses such as the flu. Length of sickness: Viral infections that hang around for a while can sometimes morph into a bigger problem, such as a sinus infection. If you stay sick longer, bacteria may appear and cause secondary bacterial infections—like in cases of viral pneumonia. You need to keep taking prescribed antibiotics until your prescription is finished. Don't stop taking them just because you feel better. In some cases, if you stop antibiotics too soon, the bacteria may remain present and cause another infection. Side Effects of Antibiotics Antibiotics have some side effects, the most common being diarrhea, nausea, rash, and yeast infections. Antibiotics can affect gut health as well. They can reduce the variety of good bacteria species in the body and how they work. There are other possible side effects, such as: C. diff infection—a serious infection that may lead to severe damage to the colon and can be fatal Changes in electrolytes, like hypoglycemia Fever Infections that are resistant to antibiotics Seizures Severe allergic reactions Thrombocytopenia Antibiotics can sometimes interact with other medications. Based on how the body metabolizes the drug, they might increase or decrease the time of either drug. Contact a healthcare provider if you develop any side effects from taking antibiotics. When Not To Take Antibiotics You don't need to take antibiotics in certain situations. They are unneeded when: You finish your prescribed dosage and have a resolved illness Prescribed antibiotics are someone else’s Your illness is a viral infection, like flu or bronchitis Why Don't Antibiotics Treat Viral Illnesses? Antibiotics are only effective against bacterial infections because they target the metabolic functions of bacteria (e.g., cell repair).Specific treatments don't exist for several viruses; recommendations will likely be for treatments to reduce and relieve symptoms. Antiviral drugs treat other viruses. These drugs target viral replication inside affected cells since viruses can't grow independently like bacteria. Other than causing side effects, using antibiotics when you don't need them can lead to antibiotic resistance. Bacteria can change and become resistant to antibiotics with repeated exposure. A Quick Review Antibiotics can be prescribed for bacterial infections, such as UTIs, though they aren't needed for all bacterial infections. They do not work for treating viral infections like colds or the flu. Some symptoms, like fevers, may help healthcare providers determine the need for antibiotics. Finishing the entire course of antibiotics is crucial even if you feel better. Antibiotics can cause various side effects like diarrhea and yeast infections. Overusing antibiotics might lead to antibiotic resistance, where antibiotics no longer work against the bacteria they are supposed to help the body get rid of. Was this page helpful? Thanks for your feedback! Tell us why! Other Submit 14 Sources Health.com uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy. MedlinePlus. Antibiotics. Baquero F, Levin BR. Proximate and ultimate causes of the bactericidal action of antibiotics. Nat Rev Microbiol. 2021;19(2):123-132. doi:10.1038/s41579-020-00443-1 Merck Manual Professional Version. Overview of antibacterial drugs. Centers for Disease Control and Prevention. Be antibiotics aware: smart use, best care. Centers for Disease Control and Prevention. 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