When Do You Really Need Antibiotics?

When you feel sick, it’s normal to want to take some medicine to feel better. Antibiotics are sometimes the answer. Unfortunately, they are the wrong answer in many situations and can make you worse instead of better. You and your healthcare provider need to work together to decide if and when you need to take antibiotics.

For example, when you have a serious bacterial infection (illness caused by a specific bacteria), you will need antibiotics. Some examples include bacterial pneumonia, bacterial meningitis, and bacterial urinary tract infections (UTIs).

But how do you know when you need antibiotics? Here’s what you need to know about which infections and symptoms usually require antibiotics, along with what questions to discuss with your healthcare provider when you find yourself sick. We’ll also cover how antibiotics work and how long it takes for them to work to help treat your infection.

How do antibiotics work?

Antibiotics are prescription-only medications that stop disease-causing bacteria from growing and replicating in your body. “Replicating” means making copies of themselves. It’s how bacteria go from an invasion to a full-blown infection.

Understanding how antibiotics work can be complicated. First, there are many classes of antibiotics that work in various ways. Second, different antibiotics treat infections in different parts of the body. Here are some examples of commonly used antibiotic classes:

• Penicillins (penicillin v, amoxicillin): These antibiotics work by preventing bacteria from replicating by interfering with their cell walls, or the outer portion of cells.

• Cephalosporins (cephalexin): Similar to penicillins, this class of antibiotics attaches itself to a protein in the cell wall to prevent the bacteria from replicating.

• Fluoroquinolones (ciprofloxacin): This type of antibiotic focuses on the bacteria’s DNA and causes it to break.

• Aminoglycosides (gentamicin): Aminoglycosides prevent the bacteria from making an effective outer protective layer (cell membrane).

• Macrolides (azithromycin): This class of antibiotics block the bacteria from making the proteins they need to survive.

• Tetracyclines (doxycycline): Like macrolides, this set of antibiotics also block the bacteria from making essential proteins.

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What antibiotics can’t do is kill organisms that are not bacteria. Antibiotics do not work to treat infections caused by viruses (such as influenza and COVID-19) or fungi (for example, yeast infections).

How long does it take antibiotics to work?

This can vary based on which antibiotic you are using and what you are taking the antibiotic for. 

Typically, you can expect your symptoms to improve within 1 to 3 days, depending on the infection, how unwell you are, and provided that the antibiotic you are taking is right for the infection you have.

How do I know when to take antibiotics?

This is complicated — which is why it’s best to share all symptoms you might be experiencing with a healthcare provider. They can help you determine if you need antibiotics.

The first step is to know whether you have an infection at all. Signs you could have an infection include:

• Pain in the area of the infection

• Swelling

• Enlarged or painful glands (lymph nodes)

• Liquid or discharge draining from somewhere it shouldn’t

• Fever

• Nausea and vomiting

• Muscle aches

• Tiredness

• Reduced appetite

But just because you have an infection doesn’t mean it is caused by a bacteria. In fact, many everyday infections are viral, rather than bacterial. 

Sometimes, your healthcare provider can tell an infection is bacterial just by examining you and asking questions about your symptoms. In other cases, they may want to take samples (e.g., saliva, urine, skin cells) and run tests to find out what type of infection it is. They won’t always get it right the first time. Sometimes, it’s a question of waiting to see what happens and whether your symptoms improve.

Which common infections require antibiotics?

People who feel sick might request antibiotics, even when antibiotics are unlikely to help. Below, we’ll talk about some common infections and what you should know about treating them.

Cold and flu

The common cold and the flu are caused by viruses, so antibiotics won’t help. Instead, you’ll want to focus on managing your symptoms. If you have the flu, your healthcare provider may recommend an antiviral medication like Tamiflu (oseltamivir).

If your cold or flu lasts for 2 weeks or more, you may be more likely to develop a bacterial sinus infection or pneumonia. In these cases, it’s important to visit a healthcare provider to talk about your symptoms. If they prescribe antibiotics, it’s because you’ve developed a bacterial infection on top of your cold or flu.

Sinus infections

Sinus infections occur when fluid builds up in the air-filled pockets in your face (sinuses), allowing germs to grow. Symptoms include pain or pressure in your face, a runny or stuffy nose, headache, and postnasal drip (mucus dripping down the back of your throat).

Most sinus infections resolve on their own in 1 to 2 weeks, and don’t require antibiotics. On top of that, sinus infections can be caused by bacteria or viruses, and only bacterial sinus infections should be treated with antibiotics. It’s not practical to test for bacteria in the sinuses, so the recommendation is to wait and treat the infection with antibiotics if certain symptoms last for more than 10 days.

Urinary tract infections (UTIs)

A UTI is bacteria in your urine that is causing symptoms, like discomfort when you pee or lower back pain. UTIs should almost always be treated with antibiotics, since they are caused by bacteria. A UTI can affect any part of the urinary tract — such as the bladder or the kidneys — and cause symptoms like pelvic pain and frequent urges to urinate. A bladder infection isn’t typically as serious as a kidney infection, but an untreated bladder infection can spread to the kidneys and cause severe pain and life-threatening kidney damage.

Common antibiotics providers prescribe for UTIs are cephalexin, sulfamethoxazole-trimethoprim, nitrofurantoin, and ciprofloxacin.

Sore throat, strep throat, and tonsillitis

Inflammation of your throat or tonsils can cause soreness and pain, and you may or may not need antibiotics to treat it. As discussed, if your symptoms are caused by a virus (like a cold or flu virus), you won’t need antibiotics. But if you have a sore throat due to bacteria — for instance, strep throat or bacterial tonsillitis — you will need antibiotics.

Strep throat happens more often in children than in adults; The only way to know for sure if you have it is for a healthcare provider to swab your throat and test it. For strep throat, your provider may prescribe antibiotics like penicillin, amoxicillin, or erythromycin. Penicillin also treats bacterial tonsillitis.

Bronchitis

Bronchitis is almost always viral, so antibiotics aren’t recommended. Bronchitis, a common result of colds or other respiratory infections, is inflammation of the lung’s airways and can cause symptoms like cough, mucus, and difficulty breathing. Usually, it resolves on its own in a little over a week.

Ear infections

Ear infections mostly affect children and can cause symptoms like pain, difficulty hearing, and drainage of fluid that are caused by inflammation and fluid buildup in the middle ear. 

But sometimes, these symptoms can occur even without an infection. The CDC recommends antibiotic treatment only for middle ear infections that are severe, or last longer than 2 to 3 days.

For an ear infection, your child’s pediatrician may prescribe antibiotics or recommend the “wait and watch” approach where you wait 2 to 3 days to see if the symptoms let up. If they don’t, you then start on antibiotics. Ear infections are most often treated with amoxicillin or amoxicillin/potassium clavulanate. 

Young children can sometimes have multiple ear infections in a year, but if the same antibiotics are used each time, they may not work as well for future infections. That’s because your body becomes used to these antibiotics (antibiotic resistance). To help prevent antibiotic resistance, providers often alternate between prescribing amoxicillin and amoxicillin/potassium clavulanate.

Pneumonia

Pneumonia is a viral or bacterial infection where the air sacs in your lungs become inflamed and filled with fluid. It can be especially serious in people with weak immune systems — like very young, older, or very sick people. Pneumonia can happen on its own or as a complication of other infections like the flu.

Since pneumonia can be deadly, all cases of bacterial pneumonia should be treated with antibiotics. The exact treatment will depend on where the infection may have happened. If you get pneumonia while you are hospitalized, that’s known as hospital-acquired pneumonia. If you haven’t been hospitalized recently, chances are you caught pneumonia elsewhere; that’s called community-acquired pneumonia.

In either case, you’ll likely receive multiple antibiotics. Treatment of community-acquired pneumonia may include oral antibiotics like azithromycin, doxycycline, and/or levofloxacin. Intravenous (IV) antibiotics like vancomycin and piperacillin/tazobactam are used to treat hospital-acquired pneumonia.

When should I not use antibiotics?

Avoid using antibiotics that were not prescribed by your healthcare provider.

If your illness is not due to a bacteria, you should not use antibiotics. Antibiotics won’t help, and they can cause serious side effects.

Should I get antibiotics every time I’m sick?

No. You should not get antibiotics every time that you are sick. They are powerful medications that should only be used in particular situations.

Many times when you are sick, especially with cold or upper respiratory symptoms, the illness is due to a virus. Viral illnesses do not respond to antibiotics. Your body's immune system fights viral infections.

Questions to ask a healthcare provider

It’s normal to have questions about antibiotics. It’s a good idea to bring a list of questions to any visit with a healthcare provider. 

Antibiotics aren’t completely risk-free, so you’ll want to make sure you understand why you’re taking them and how to take them safely if your provider prescribes them. Consider asking these questions:

• How does this antibiotic work to treat my infection?

• What should I do if I don’t start feeling better even after I’ve finished my antibiotics?

• What kinds of side effects should I expect?

• How long will it take for the antibiotics to work?

• Could this antibiotic interact with any medications or supplements I’m taking already? If you are taking other medications, it’s helpful to create a list to share with a provider and pharmacist.

• How will I know if I’m allergic to an antibiotic?

Between your healthcare provider’s advice and these tips on how to take antibiotics, you should be well-prepared for a safe course of treatment.

Keep in mind, if your provider doesn’t prescribe antibiotics, it doesn’t mean you won’t get better. Answers to these questions may help you understand how you can manage your infection without antibiotics:

• Why won’t antibiotics treat this infection?

• How can I manage the symptoms of this infection without antibiotics?

• What should I do if I don’t start feeling better soon?

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Written by:

Meg Burke, MD

Meg Burke, MD, is a practicing primary care geriatrician in the Denver, Colorado area. She is board-certified in internal medicine and geriatric medicine, and received her undergraduate and medical degrees from Georgetown University in Washington, D.C. After graduating from medical school, Dr. Burke completed her internal medicine residency at Johns Hopkins Bayview Medical Center and her two years of subspecialty training in geriatric medicine at the Johns Hopkins Hospital in Baltimore, Maryland.

Edited by:

Samvida Patel, MNSP, INHC

Samvida Patel, MNSP, INHC, is a health editor at GoodRx. She is a nutritionist and integrative nutrition health coach with over 8 years of experience in health communications.

Reviewed by:

Sophie Vergnaud, MD

Sophie Vergnaud, MD, is the Senior Medical Director for GoodRx Health. An experienced and dedicated pulmonologist and hospitalist, she spent a decade practicing and teaching clinical medicine at academic hospitals throughout London before transitioning to a career in health education and health technology.

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