When Do You Really Need Antibiotics?

Megan N. Brown, PharmD, RPh
Megan N. Brown, PharmD, RPh is a public health pharmacist with fellowship training in drug information and health communications.
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Deciding whether to wait out a sickness or head to the doctor’s office for antibiotics can be a tough choice to make. Untreated bacterial infections can have serious and deadly consequences, but side effects of antibiotics are no fun either. This post will give you an idea of what types of infections usually do—or don’t—require antibiotics.



How do antibiotics work?

Antibiotics are prescription-only medications that fight bacteria in one of two ways: they either kill bacteria or stop bacteria from growing. Antibiotics don’t treat infections caused by viruses (like the common cold or flu) or fungi (like athlete’s foot or ringworm).

Understanding how antibiotics work can be complicated. First, there are many classes of antibiotics: penicillins like amoxicillin, cephalosporins like cephalexin, aminoglycosides like gentamicin, and more. And then within each class, individual antibiotics treat different types of infections. Bactrim (sulfamethoxazole/trimethoprim), for example, can treat urinary tract infections but can also be used to treat traveler’s diarrhea and infected wounds.


How can I tell if I need antibiotics?

You might recognize these signs of an infection if you’ve had one:

But these signs won’t tell you if the infection is bacterial, viral or fungal. If you think you have an infection, you’ll need to visit a doctor to find out whether or not antibiotics can help treat it.

Sometimes, your doctor 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.



Which common infections require antibiotics?

Patients often ask doctors for antibiotics, not knowing whether antibiotics actually treat those conditions. And doctors tend to over-prescribe antibiotics for conditions that don’t always require antibiotics. Below, we’ll talk about some common infections and what you should know about treating them.


Colds and flu

Colds 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 doctor 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 the doctor 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

Healthcare providers prescribe antibiotics for sinus infections the most, but most sinus infections resolve on their own in 1 to 2 weeks. 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)

UTIs should almost always be treated with antibiotics, since they are usually 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 doctors prescribe for UTIs are Bactrim, 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. If your sore throat is caused by a virus (like a cold or flu virus), you won’t need antibiotics. But when it’s due to bacteria, as in strep throat (or streptococcal pharyngitis) and bacterial tonsillitis, you will.

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




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 are caused by inflammation and fluid buildup in the middle ear. But sometimes, these symptoms can occur even without an infection. The CDC recommends that only true middle ear infections be treated with antibiotics.

For an ear infection, your child’s doctor may prescribe antibiotics or recommend the “wait and watch” approach where you wait 48 to 72 hours to see if the symptoms let up and if they don’t, you then start on antibiotics. 

Ear infections are most often treated with amoxicillin or amoxicillin/potassium clavulanate (Augmentin). 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. To help prevent antibiotic resistance, doctors often alternate between prescribing amoxicillin and amoxicillin/potassium clavulanate.



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, very old 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 as soon as they are diagnosed. 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. IV (intravenous) antibiotics like vancomycin, Zosyn (piperacillin-tazobactam) and levofloxacin are used to treat hospital-acquired pneumonia.


Questions to bring up at your doctor’s visit

It’s normal to have questions about antibiotics, so don’t hesitate to ask your doctor!

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 doctor prescribes them. Consider asking these questions:

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

If your doctor 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:


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