Amoxicillin oral forms side effects: A detailed guide

Specifically, the Food and Drug Administration (FDA) has approved amoxicillin oral forms to treat:

• bacterial infections, including those of the ear, nose, throat, genitourinary tract, skin, and lower respiratory tract
• Helicobacter pylori (H. pylori) infection and duodenal ulcers, together with other medications

This article describes possible side effects of amoxicillin oral forms. You’ll also find information on cost savings and coupon options for amoxicillin.

Amoxicillin oral forms are a generic version of the brand-name drug Amoxil. But the brand-name version is no longer available. Amoxicillin oral forms come as capsules and tablets you swallow and tablets that you chew and swallow. Amoxicillin also comes as a powder that’s mixed with water at your pharmacy to form a liquid suspension that you swallow. A suspension is a type of liquid mixture.

You can explore this overview article to learn more about amoxicillin oral forms, including the drug’s uses, dosage, ways to save on cost, and more.

More common side effects of amoxicillin

Amoxicillin oral forms may cause mild or serious side effects. Below are some of the more common side effects of this medication.

Commonly reported side effects of amoxicillin oral forms include:

• rash
• nausea
• vomiting
• diarrhea*

More common side effects in people taking amoxicillin for Helicobacter pylori (H. pylori) infection are listed below.

For people taking amoxicillin with clarithromycin and lansoprazole, these were common side effects:

• diarrhea*
• headache
• altered sense of taste

For people taking amoxicillin with lansoprazole, these were more common side effects:

• diarrhea*
• headache

* To learn more about this side effect, see the “Side effects of amoxicillin in detail” section below.

Mild side effects of amoxicillin

Amoxicillin may cause certain mild side effects. Usually, mild side effects are temporary and can be managed. Tell your doctor or pharmacist if you have side effects that don’t go away or become bothersome.

Mild side effects of amoxicillin oral forms that occurred in studies include:

• vomiting
• nausea
• dizziness
• headache
• diarrhea*
• rash*
• mild allergic reaction*

* To learn more about this side effect, see the “Side effects of amoxicillin in detail” section below.

Amoxicillin oral forms may cause more mild side effects than those listed above. For details, see the drug’s prescribing information.

Serious side effects of amoxicillin

Amoxicillin may cause certain serious side effects. If you have any serious side effects from amoxicillin oral forms, call your doctor right away. But if you think you’re having a medical emergency or your side effects feel life threatening, take immediate action. Call 911 or a local emergency number, or go to the nearest emergency room.

After the Food and Drug Administration (FDA) approves a drug, it tracks and reviews side effects of the medication. Visit MedWatch’s website if you’d like to notify the FDA about a side effect you’ve had with amoxicillin oral forms.

Serious side effects of amoxicillin oral forms that occurred in studies include:

• developing drug-resistant bacteria (bacteria that no longer responds to the treatment)
• severe skin reactions*
• severe diarrhea caused by Clostridioides difficile (C. diff)*
• severe allergic reaction*

* To learn more about this side effect, see the “Side effects of amoxicillin in detail” section below.

Common questions about side effects of amoxicillin

Here are answers to some common questions about side effects of amoxicillin oral forms. If you have other questions, talk with your doctor or pharmacist.

Are side effects of amoxicillin different in women vs. men?

Typically, amoxicillin causes the same side effects in females and males.* There haven’t been reports of any side effects being different between these groups of people.

The drugmaker recommends that amoxicillin be taken during pregnancy only if it’s clearly needed. For more information, see “Amoxicillin and pregnancy” in the “Warnings for amoxicillin” section below.

Talk with your doctor if you have more questions about this.

* Sex and gender exist on spectrums. In this article, we use the terms “male” and “female” to refer to a person’s sex assigned at birth.

Will amoxicillin 500 mg cause different side effects compared with other strengths?

It’s possible. In general, higher strengths of medications can increase your risk of side effects, but this is not always the case. Studies from amoxicillin’s drugmaker didn’t report side effects based on the different strengths of the drug.

Talk with your doctor or pharmacist if you have concerns about side effects with differing strengths of amoxicillin.

How long do side effects of amoxicillin last?

How long side effects of a drug last depends on the side effect itself. Some side effects of amoxicillin may last only a few days to weeks. But other side effects may last longer or become severe or bothersome.

Side effects can also occur after stopping amoxicillin treatment. For example, severe diarrhea caused by Clostridioides difficile (C. diff)* has occurred during treatment and more than 2 months after treatment was stopped.

Let your doctor or pharmacist know if you have concerns about how long side effects of amoxicillin last.

* To learn more about this side effect, see the “Side effects of amoxicillin in detail” section below.

Can amoxicillin cause dizziness?

Yes, it might. Dizziness wasn’t reported as a side effect during studies of amoxicillin. But it was seen in some people taking amoxicillin after the drug was approved for use. It’s unclear how often dizziness happens or whether amoxicillin causes it.

Be sure to tell your doctor if you have dizziness while taking amoxicillin. They can recommend the best way to manage your symptoms.

How do the side effects of amoxicillin in older adults compare with those in younger adults?

There aren’t any known differences in how older adults respond to amoxicillin compared with younger adults.

The drugmaker reviewed some studies to see whether there was a difference between people ages 65 years and older and people who were younger. No differences were found, but it’s possible that older adults may be more sensitive to amoxicillin.

This drug is cleared from the body by the kidneys. Older adults may be more likely to have reduced kidney function, which can increase the risk of side effects. In this case, doctors may adjust amoxicillin’s dosage and monitor kidney function during treatment.

If you’d like to know more about amoxicillin treatment given your age, talk with your doctor or pharmacist.

Does amoxicillin cause long-term side effects?

It’s possible. Many of amoxicillin’s side effects are mild, temporary, and may go away without treatment.

But it’s possible for amoxicillin to cause long-term side effects. These are side effects that start either:

• during treatment and continue for a long time, possibly after you stop taking the drug, or
• after treatment ends

Long-term side effects reported in amoxicillin’s studies included:

• severe diarrhea caused by Clostridioides difficile (C. diff)
• severe skin reactions
• severe allergic reaction

To learn more about these side effects, see the “Side effects of amoxicillin explained” section below. Talk with your doctor or pharmacist if you have more questions about the long-term side effects of amoxicillin.

Does amoxicillin cause tooth discoloration?

Yes, amoxicillin can cause tooth discoloration, such as brown, yellow, or gray staining. This side effect was seen in people taking the drug after it was approved for use.

Most of these cases occurred in children. In most cases, the discoloration improved or went away with tooth brushing or dental cleaning.

If you’d like to know more about this, talk with your doctor or dentist.

Coupon for amoxicillin

Visit this page to access Optum Perks coupons and get price estimates for amoxicillin when you use the coupons. These coupons can provide significant savings on your prescription costs. 

Note: Optum Perks coupons cannot be used with insurance copays or benefits.

Side effects of amoxicillin in detail

Below you’ll find details on some of the side effects of amoxicillin oral forms.

Diarrhea caused by C. diff

Amoxicillin may cause a severe type of diarrhea caused by a bacteria called Clostridioides difficile (C. diff). This condition is known as Clostridioides difficile-associated diarrhea (CDAD).

CDAD can cause symptoms ranging from mild diarrhea to severe inflammation in the colon that leads to death. CDAD can be immediate, or it can occur 2 months or more after you’ve received amoxicillin.

Treatment with antibiotics, including amoxicillin, changes the usual flora of the colon. Flora is made up of bacteria and other organisms. This can lead to an overgrowth of certain organisms, such as C. diff.

What might help

Call your doctor immediately or seek emergency medical care if you have severe diarrhea while taking amoxicillin.

Diarrhea caused by C. diff may be life threatening and often requires treatment in a hospital. Your doctor will likely have you stop taking amoxicillin. They may also prescribe treatment with fluids and certain medications to help reduce your symptoms.

Severe skin reactions

Amoxicillin may cause severe cutaneous adverse reaction (SCAR). SCARs are serious skin conditions.

Examples of SCARs include:

• Stevens-Johnson syndrome
• toxic epidermal necrolysis
• drug reaction with eosinophilia and systemic symptoms
• acute generalized exanthematous pustulosis (a rare skin reaction that can cause a rash, fever, and high levels of white blood cells)

Symptoms of these skin reactions can include:

• skin rash
• blistering of the eyes, lips, or mouth
• red or discolored skin
• peeling skin
• fever

What might help

Call your doctor immediately or seek emergency medical care if you notice symptoms of a severe skin reaction while taking amoxicillin. These reactions are life threatening and often require treatment in a hospital.

Your doctor will likely have you stop taking amoxicillin if you develop a severe skin reaction. They can discuss alternate treatment options with you if this occurs.

Allergic reaction

For some people, amoxicillin oral forms can cause a serious and possibly fatal allergic reaction. This is also known as anaphylaxis.

This reaction is more likely to occur if you’ve had an allergic reaction to penicillin or have sensitivity to multiple allergens.

Symptoms of allergic reaction can be mild or serious, and they may include:

• itchiness
• skin rash
• swelling under the skin, usually affecting eyelids, lips, hands, or feet
• swelling of the mouth, tongue, or throat, which can make it hard to breathe
• flushing (temporary warmth, redness, or deepening of skin color)

Ways to manage

Before taking amoxicillin, tell your doctor if you’ve had an allergic reaction to penicillin antibiotics, cephalosporins, or other allergens. If you have an allergic reaction to amoxicillin, stop taking the medication and tell your doctor. 

For mild allergic reaction symptoms, such as a mild rash, call your doctor right away. They may recommend treatments to help manage your symptoms. They’ll also let you know whether you should keep taking the medication.

For severe allergic reaction symptoms, such as swelling or trouble breathing, call 911 or your local emergency number right away. These symptoms require immediate medical care because they can become life threatening. If you’ve had a serious allergic reaction to amoxicillin oral forms, your doctor may recommend taking a different medication instead.

Warnings for amoxicillin

Below are some factors you may want to discuss with your doctor before taking amoxicillin oral forms.

Warnings

It may not be safe for you to take amoxicillin oral forms if you have specific health conditions. These are sometimes called drug-condition interactions. Other things may also affect whether amoxicillin is a safe treatment option for you.

Before taking amoxicillin oral forms, tell your doctor about your health and medications you take. Things to consider include:

• past allergic reaction to amoxicillin
• diarrhea from past antibiotic treatment
• use of birth control pills, as amoxicillin may make them less effective to prevent pregnancy
• past severe skin reactions
• past mononucleosis
• kidney problems
• liver problems

Amoxicillin and pregnancy

The drugmaker recommends that amoxicillin be taken during pregnancy only if it’s clearly needed. Talk with your doctor before taking amoxicillin during pregnancy. And let them know if you have concerns about this.

Keep in mind that amoxicillin may make birth control pills less effective to prevent pregnancy. If you take birth control pills, you may need to use a backup method to help prevent pregnancy. An example is condoms.

Amoxicillin and breastfeeding

Penicillin antibiotics, such as amoxicillin, pass into breast milk. So, amoxicillin should be used with caution while breastfeeding. That said, the drug is considered safe to use while breastfeeding.

Be sure to talk with your doctor or child’s doctor before taking amoxicillin while breastfeeding.

Amoxicillin and alcohol

Amoxicillin oral forms aren’t known to interact with alcohol.

Still, your doctor may suggest limiting alcohol intake while you’re taking amoxicillin. This is because amoxicillin can cause dizziness and digestive side effects, such as nausea, vomiting, and diarrhea. Alcohol can also cause these side effects.

If you drink alcohol, talk with your doctor or pharmacist about whether it’s safe to consume it during treatment with amoxicillin.

What to ask your doctor

This article describes common and serious side effects of amoxicillin oral forms. If your doctor prescribes this medication, they can discuss possible side effects with you. Let your doctor know if you have concerns or questions about treatment with this medication.

Here’s a list of some possible questions you may want to ask your doctor:

• Does my medical history increase my risk of side effects with amoxicillin?
• Will any of my medications interact with amoxicillin and increase my risk of side effects?
• If I have side effects from amoxicillin, should I try taking a lower dose of the drug?

Related articles

• Amoxicillin over-the-counter alternative
• Amoxicillin dosage
• How long does amoxicillin take to work?
• How to get amoxicillin without seeing a doctor
• How long does amoxicillin stay in your system?

Disclaimer: Optum Perks has made every effort to make certain that all information is factually correct, comprehensive, and up to date. However, this article should not be used as a substitute for the knowledge and expertise of a licensed healthcare professional. You should always consult your doctor or another healthcare professional before taking any medication. The drug information contained herein is subject to change and is not intended to cover all possible uses, directions, precautions, warnings, drug interactions, allergic reactions, or adverse effects. The absence of warnings or other information for a given drug does not indicate that the drug or drug combination is safe, effective, or appropriate for all patients or all specific uses.