Key takeaways

  • Amoxicillin commonly causes gastrointestinal side effects like diarrhea, nausea, and vomiting because it disrupts beneficial gut bacteria. Other common effects include headaches, taste changes, vaginal yeast infections, and rash.
  • Most side effects resolve on their own once you stop taking amoxicillin, though diarrhea can sometimes persist for up to 2 months. Managing symptoms may include eating bland foods, taking probiotics, or using over-the-counter antifungal or antihistamine products.
  • Seek emergency care if you experience signs of anaphylaxis, such as difficulty breathing, wheezing, widespread rash with swelling, or swelling of the lips, face, or tongue.

Amoxicillin is an antibiotic that doctors prescribe to treat several different bacterial infections. These include infections of the ears, nose, throat, and upper airway. Like any medication, amoxicillin may cause some side effects that can range from mild to serious.

Most amoxicillin side effects are not serious and may go away on their own with time. Let’s take a look at some of the possible effects of amoxicillin and how to manage them.

Gastrointestinal symptoms are among the most common side effects of taking amoxicillin. Examples of these include:

  • diarrhea
  • nausea
  • vomiting

This typically happens because while antibiotics like amoxicillin kill off the bacteria causing an infection, they can also harm the good bacteria in the gut. This can disrupt your digestive system, leading to these symptoms.

Other common side effects include:

  • headaches
  • changes in taste
  • vaginal yeast infections
  • rash

If these symptoms persist or are severe, consider talking with your doctor. A doctor can recommend ways to reduce side effects, such as making specific dietary changes. If possible, they may prescribe different antibiotics instead.

It is possible for an individual to experience side effects even if they have taken amoxicillin in the past without any side effects.

Warning: If you experience severe, prolonged abdominal pain or see blood in your vomit or stool, seek immediate medical attention.

In rare cases, people may experience potentially life threatening side effects when taking amoxicillin. Examples of these include:

  • problems breathing
  • wheezing
  • hives
  • itching
  • rash
  • skin blistering
  • skin peeling
  • swelling in the eyes, face, lips, throat, or tongue
  • severe diarrhea
  • stomach cramping

It is also possible to experience a so-called superinfection due to taking amoxicillin. These superinfections can be fungal or bacterial, and they include Clostridium difficile colitis.

This type of colitis is especially harmful because it can cause severe and prolonged diarrhea that damages the intestines.

You should seek medical attention immediately if you experience life threatening side effects, such as problems breathing.

Experiencing side effects? After the Food and Drug Administration (FDA) approves a drug, it tracks and reviews its side effects. If you develop a side effect while taking this medication and want to report it to the FDA, you can visit MedWatch or call 800-FDA-1088.

Doctors have identified certain factors that may contribute to the likelihood of a person experiencing an amoxicillin reaction. These factors include:

Amoxicillin can cause skin reactions, such as a rash, in infants. Doctors usually prescribe amoxicillin to treat infections in young people because the body absorbs it well. Rashes in young people typically present as small discolored bumps. They may be mildly itchy and are usually on the trunk of the body.

A person may take antibiotics for a long time for severe or continued infections, such as osteomyelitis. Doing so puts them at higher risk of long-term complications, including crystalluria (cloudy urine), hemolytic anemia, and nephritis.

Those with a history of penicillin allergy may be more at risk of experiencing side effects relating to amoxicillin. Penicillin has chemical similarities to amoxicillin. As a result, a person who is allergic to penicillin may be more likely to have an allergic reaction to amoxicillin.

Note: Doctors have not found that penicillin allergies are inherited, according to the American Academy of Allergy, Asthma & Immunology. Due to this, a person does not necessarily need to avoid this antibiotic if a family member is allergic.

Here are some tips to manage the possible side effects of amoxicillin.

To manage effects like diarrhea, nausea, and vomiting, doctors might recommend altering your diet, eating bland foods that are easy for your stomach to digest.

They might also recommend including a probiotic supplement in your diet to help the good bacteria in your gut thrive, reducing the chance of these effects from antibiotics.

Vaginal yeast infections are a common side effect of antibiotics because antibiotics can disrupt the good bacteria in your vagina, causing an overgrowth of the yeast that naturally lives there.

A doctor can prescribe antifungal creams or tablets if you experience this effect. You can also find over-the-counter (OTC) antifungal vaginal creams at drugstores or online.

A mild rash is common with amoxicillin treatment, especially in children, and it typically isn’t a sign of a serious reaction. In most cases, the rash will disappear on its own once the medication has been stopped and cleared from the body.

Doctors might recommend some OTC antihistamines, such as Benadryl, to manage itching.

People usually take a short-term course of amoxicillin antibiotics, so the side effects should not last long. In most cases, when a person stops taking the antibiotics, they will stop experiencing side effects.

If a person experiences prolonged bouts of diarrhea along with fever and stomach pain after taking amoxicillin, they should talk with their doctor. People have reported experiencing diarrhea for as long as 2 months after they stopped taking amoxicillin.

Medical Perspective

Why is it important not to stop antibiotics early, even if symptoms improve before the full course is finished?

“It’s important to take your full course of antibiotics, even if you start to feel better sooner. Stopping an antibiotic early can leave some bacteria alive, which may allow the infection to return. It also increases the chance that the remaining bacteria become harder to treat.

Finishing the full course helps make sure the infection is fully cleared.”

— Stan Saji, PharmD, MBA, RPh

Learn more about antibiotic resistance.

Quotes represent the opinions of our medical experts. All content is strictly informational and should not be considered medical advice.

A person should seek emergency medical attention if they think that they are experiencing anaphylaxis — a life threatening reaction — after taking amoxicillin.

They are at higher risk of a severe reaction if they have had an anaphylactic reaction to penicillin or cephalosporin antibiotics in the past.

Anaphylaxis symptoms include:

  • problems breathing
  • wheezing
  • a rash that causes swelling and spreads across most of the body
  • swelling of the lips, face, and tongue

A doctor will usually treat these reactions with steroids and antihistamines, such as diphenhydramine (Benadryl). Typically, they will advise a person to stop taking amoxicillin if they have experienced a severe reaction.

If a person has mild diarrhea that is tolerable, they usually do not need to contact their doctor. However, if they are uncertain whether a side effect that they are experiencing is normal, they should call their doctor.

If you have a bacterial infection, your doctor will likely prescribe an antibiotic like amoxicillin. If you’ve been prescribed this drug, here are some next steps to consider to manage side effects:

  • Start taking a probiotic to help prevent side effects
  • Monitor your side effects, their severity, and how long they last
  • Seek medical treatment if you have any concerns about your side effects

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