Medically Approved

Amoxicillin — the powerhouse antibiotic

Yound girl being given a spoonful of amoxicillin

Here’s everything you need to know about this mighty infection-fighting medication, from when to use it to what side effects to expect. 

Mark Ray

By Mark Ray

Chances are, you’ve been taking amoxicillin occasionally since you were a little kid. Not that you would have known its name. But you probably remember the bubblegum taste. And the look of the pink liquid as it poured into the spoon. 

Doctors prescribe this antibiotic to babies, big kids and adults. It’s a powerful weapon in the fight against a range of infections, from earaches to urinary tract infections (UTIs) to pneumonia. “Amoxicillin is probably the most known and widely used antibiotic in primary health care settings,” says Francesca Chiara, PhD. She’s the director of the Antimicrobial Stewardship Project at the University of Minnesota’s Center for Infectious Disease Research and Policy. 

Amoxicillin can’t cure every infection. And you have to follow the directions in order to reap its disease-fighting benefits. So read on to find out what this antibiotic can do — and how to take it correctly.  

Recommended reading: From amoxicillin to Z-paks: Here’s how doctors choose the right antibiotic for you.   

What is amoxicillin?  

Amoxicillin is a type of antibiotic, along with ampicillin, methicillin and other medications. Think of it as a cousin of the original antibiotic, penicillin. Penicillin and other antibiotics are used to treat mild and serious bacterial infections such as strep throat, bacterial meningitis and whooping cough.  

These types of antibiotics work by destroying the walls of the bacterial cells so that the bacteria die. They’re considered broad-spectrum antibiotics, which means they treat many different types of bacteria. Amoxicillin, for instance, targets infections of the ear, nose, throat, chest, urinary tract and skin.  

The key: All of those infections are caused by bacteria. Like all antibiotics, amoxicillin is powerless against viruses. So don’t expect a prescription if you have a cold, the flu or COVID-19. 

Amoxicillin is often used in combination with another medication called clavulanic acid, which keeps bacteria from fighting back. “If you take amoxicillin with clavulanic acid, you increase the power of the antibiotic. So you’re more likely to fight off the infection,” Chiara says. Doctors tend to prescribe the combo for certain UTIs, for instance. 

How to take amoxicillin  

This medication comes as a capsule, tablet, chewable tablet or liquid. But no matter which form you take, keep these tips in mind to get all the benefits of amoxicillin.   

  • Take it with food. Either with a meal or a snack. That will cut down the side effects (more on those later). 
  • Take it on time. Take the antibiotic exactly as prescribed by your doctor, says Chiara. Don’t skip doses, and stick to a schedule as much as possible, she adds. You must keep a certain level of the medication in your body to get the maximum infection-fighting benefits. 
  • Take it for as long as the doctor ordered. You’ll feel better after the first few days, which means you might be tempted to skip the last few days of the prescription. Don’t. If you stop early, Chiara says, “the bacteria that remain have been exposed to a small amount of antibiotic, not enough to kill them or to reduce their growth.” That means they may become resistant to amoxicillin and it won’t work as well the next time you take it. 
  • Don’t save leftover pills. First, you won’t have enough pills left to treat another infection. Besides, it might not be the right medication for the next infection anyway. (Remember, amoxicillin is just one of many kinds of antibiotic.) 

(If you’ve been given a prescription for amoxicillin, show your pharmacist this free prescription discount card. It could save you up to 80%.) 

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What are amoxicillin’s side effects? 

Amoxicillin may come with some side effects, though they’re usually not very serious. But some of them could be a sign of an allergic reaction. Here’s what you need to know: 

Gastrointestinal issues: Besides killing bad bacteria, amoxicillin kills the good bacteria in your gut. Taking a combination of amoxicillin and clavulanic acid could lead to unpleasant but moderate side effects such as: 

  • Diarrhea 
  • Vomiting 
  • Upset stomach 
  • Queasy stomach 

What to do: Take amoxicillin with food. Also, try taking a probiotic supplement to help with diarrhea or an upset stomach. (Ask your doctor to recommend one.) Probiotics can add good bacteria to your gastrointestinal tract and help keep things in balance. Or eat 1 or 2 servings of plain yogurt per day. The label should say “active and live cultures.” Don’t skip meals. You don’t need to change your diet either, unless your doctor tells you to. 

Skin rash: Mild skin rashes are a common side effect. They can look like dots or slightly raised bumps on your chest, back, stomach, or legs and arms. They usually appear 5 to 7 days after you start amoxicillin. But keep an eye out for more serious skin rashes, such as: 

  • Severe itching 
  • Hives 
  • Skin blisters 

What to do: A mild skin rash will go away on its own. But call the doctor if you get hives, especially if they appear a few hours after your first dose. That’s a sign of an allergic reaction. 

Other signs of an allergic reaction include: 

  • Wheezing 
  • Trouble breathing or swallowing 
  • Swelling of the face, tongue, lips or eyes 
  • Severe diarrhea 

Most people won’t have an allergic reaction. And a mild rash, queasy stomach and even diarrhea are normal reactions. But if you have severe side effects or think you might be having an allergic reaction, speak to your doctor immediately. 

Amoxicillin is truly a wonder medication. Just follow your doctor’s orders when taking it. That all but guarantees you’ll be feeling better in no time at all. 

(Be sure to download our free mobile app to find the best price on all your medications at a pharmacy near you.) 

Additional sources:
History of antibiotics: American Academy of Pediatrics 
Probiotics for gastrointestinal side effects: Cleveland Clinic 
Penicillin allergies: American Academy of Allergy, Asthma and Immunology