Key takeaways

Antibiotics like penicillin, amoxicillin, and Augmentin are prescribed for bacterial infections in children. They are ineffective for viral illnesses.
Misdiagnosis of penicillin allergy is common, affecting about 10% of children, though true allergic reactions are rare and involve symptoms like swelling, low blood pressure, and rash.
The overuse of antibiotics can lead to antibiotic resistance, making bacteria more resistant to treatment and disrupting the gut microbiome, causing adverse health effects.
To minimize antibiotic resistance, healthcare providers aim to use the narrowest spectrum antibiotic possible, switching to a narrow-spectrum option based on lab results to target the infection effectively.

As the excitement of back-to-school time approaches, one thing’s for sure: Returning to the classroom means kids will be exposed to lots of germs, including colds, the flu, and countless other viruses. As kids start school each year, bacterial infections like strep throat and pneumonia become more common, too. But what illnesses do kids need antibiotics for?

Here, doctors weigh in on the most commonly prescribed kids’ antibiotics, what they are used for, and what to expect.

7 common children’s antibiotics

Antibiotics don’t work for viral infections, but If your child has an illness that’s caused by a bacterial infection, they’ll probably be prescribed one of the following antibiotics, says Michael Grosso, MD, the chairman of pediatrics at Huntington Hospital at Northwell Health in Huntington, New York. Each antibiotic is available as a liquid or pill.

1. Penicillin

Penicillin, the very first antibiotic discovered, remains very useful for a range of bacterial infections, from strep throat, ear infections, and skin infections to life-threatening bloodstream infections. It’s normal to experience side effects such as a mild rash, diarrhea, nausea, vomiting, abdominal pain, or, rarely, a black, hairy tongue. Research estimates that about 10% of children are labeled as allergic to penicillin, but experts say about 95% of those are misdiagnosed. Signs of a true allergic reaction to the antibiotic include swelling under the skin, low blood pressure, wheezing or tightness in the chest or throat, and a rash consisting of red, itchy welts.

RELATED: Penicillins: Uses, types, brands, and safety info

2. Amoxicillin

Amoxicillin, a “second generation” penicillin, is among the most widely prescribed antibiotics for children. Amoxicillin is better absorbed from the intestine when taken orally and yields higher blood and urine levels. “It is the preferred first-line medication for most children with middle ear infections (also known as acute otitis media), acute sinusitis, sore throat due to Group A streptococci (so-called strep throat), some infections of the urinary tract, the rash phase of Lyme disease, and a variety of other infections,” Dr. Grosso says. Possible side effects of amoxicillin include nausea, vomiting, diarrhea, headache, and changes in taste.

RELATED: Amoxicillin vs. penicillin

3. Augmentin

Augmentin (amoxicillin clavulanate) is amoxicillin combined with clavulanic acid, which makes amoxicillin more active against certain bacteria that would otherwise be resistant to the drug. It is useful in certain middle ear infections, sinus infections, urinary tract infections, and infections of the skin. Or, it may be prescribed after a cat or dog bite. Side effects such as diarrhea, upset stomach, vomiting, or a mild skin rash may occur.

RELATED: Amoxicillin vs. Augmentin

4. Zithromax

Zithromax (azithromycin) is a second-line medication for ear infections, sinus infections, and throat infections. It is also used first-line for those allergic to penicillin, according to Dr. Grosso. Because it is long-acting, requiring only once-daily dosing (usually for five days), it is easy for parents to give, but it is somewhat less effective for bacterial infections than the medications mentioned above. “Importantly, azithromycin is the preferred antibiotic for certain germs called atypical bacteria, which can cause pneumonia in children and adults,” he says. Common side effects include nausea, vomiting, diarrhea, abdominal pain, and headache.

5. Biaxin

The antibiotic Biaxin (clarithromycin) may be used to treat pediatric bacterial infections, including pneumonia, bronchitis, and ear, skin, throat, and sinus infections. This medication is known not to taste good. Side effects may include diarrhea, nausea, vomiting, changes in taste, gas, and headache.

6. Keflex and Omnicef

Keflex (cephalexin) and Omnicef (cefdinir) are in the cephalosporin family, which are more distant relatives of the penicillin antibiotics. Most (but not all) people who are allergic to penicillin may be able to take these medications safely. “Cephalexin is often prescribed for urinary tract infections or skin infections, while cefdinir treats most infections that respond to Augmentin. Cefdinir can usually be taken just once a day,” Dr. Grosso says. Side effects of cefdinir include diarrhea, nausea, vomiting, abdominal pain, rash, genital itching, and headache. In addition to these side effects, cephalexin can also cause heartburn, fatigue, agitation, dizziness, confusion, and rectal itching.

RELATED: Cephalosporins: Uses, common brands, and safety info | Cefdinir vs. amoxicillin

7. Sulfonamides

Sulfonamides are among the oldest classes of antibiotics and have been widely prescribed since the 1930s. They’ve been proven effective for a variety of infectious diseases. The most commonly prescribed medication in this group is the combination agent Bactrim (sulfamethoxazole/trimethoprim), which is effective against infections of the middle ear, sinuses, urinary tract, and skin, Dr. Grosso explains. About 3-8% of people are allergic to sulfonamides, which most commonly exhibit as a rash. Common side effects include dizziness, headache, diarrhea, nausea, vomiting, loss of appetite, and nervousness.

RELATED: What are sulfonamides?

Though many other antibiotics are useful to treat infections in infants, children, and teens, the medications listed above are the most commonly prescribed, says Dr. Grosso. Some other antibiotics, such as Vancocin (vancomycin) and Flagyl (metronidazole), are typically administered intravenously in children requiring a hospital stay. Others are applied topically, such as creams or ointments, or as drops to the eyes or ears. “When appropriate, topical antibiotics are usually preferred because of their better safety profile,” Dr. Grosso says.

It’s important to note that In pediatrics, all antibiotics are dosed on a weight-based mg/kg approach that is divided into 1-3 doses per day, according to the specific drug, says Rebecca Fisk, MD, a pediatrician at Lenox Hill Hospital at Northwell Health in New York, New York.

“When a pediatrician prescribes an antibiotic for a specific illness, it is important that the dosing be adhered to and completed as directed,” she says. Parents should contact their pediatrician with any questions or if side effects develop—don’t stop using the antibiotic without your pediatrician’s okay. Medication should be given directly to the patient and not mixed in a drink or food where it may be incompletely taken.

Antibiotics that should be avoided in children

In general, fluoroquinolones such as Levaquin (levofloxacin) and tetracyclines such as Doxycycline are avoided in pediatric patients, Dr. Fisk says. That’s because tetracyclines can permanently stain the teeth. Quinolones are generally not used in children because of their potential to cause cartilage abnormalities in animal studies, although more research is needed.

When antibiotics should not be used

Antibiotics do not work on viruses. Therefore they’re ineffective for colds, runny noses (even when mucus is discolored), most sore throats, the flu, and other viral illnesses, Dr. Fisk explains. And people with allergies to specific antibiotics should avoid them too, adds Dr. Grosso.

Antibiotic resistance occurs when overexposure to antibiotics makes bacteria resistant to an antibiotic. It can also happen when antibiotics are taken too often, allowing a bacteria to learn to protect itself against the drug, says Dr. Fisk. The more antibiotics are used and over-used, the more people pass around germs that have evolved resistance to these medications, rendering the antibiotics less and less effective over time, says Dr. Grosso.

What’s more, the bacteria in our intestines and respiratory tract, or the microbiome, comprise a complex ecology with profound implications for health and disease, he adds. Overuse of antibiotics can seriously disrupt the balance of the gut microbiome, causing negative health implications. That’s why it’s important to take antibiotics only as indicated by your healthcare provider.

Avoiding antibiotic resistance

To minimize the risk of antibiotic resistance, providers should select the narrowest spectrum antibiotic available to treat the infection, Dr. Grosso says. “Under the best of circumstances, we send a culture to the lab (say from the throat, or the urine) to identify the culprit specifically.”

Broad-spectrum antibiotics are reserved for more serious infections where rapid control of the problem is necessary. Once laboratory report results show which bacteria is present and which antibiotic is sensitive to the infection, providers should switch to a narrow-spectrum antibiotic, he advises. That can help reduce the risk of antibiotic resistance. Examples of broad-spectrum antibiotics include Augmentin, clarithromycin, cefdinir, cephalexin, Zithromax, and sulfonamides. Penicillin and amoxicillin are narrow-spectrum antibiotics.