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Drug Profile

The information on this site is intended to supplement and enhance, not replace, the advice of a physician who is familiar with your medical history. Decisions about your health should always be made ONLY after detailed conversation with your doctor.

Generic drug name: amoxicillin (a mox i SILL in)
Brand name(s): AMOXIL, LAROTID
GENERIC: available FAMILY: Penicillins
Find the drug label by searching at DailyMed.

Generic drug name: amoxicillin and clavulanate (a mox i SILL in and clav YEW lan ate)
Brand name(s): AUGMENTIN
GENERIC: not available FAMILY: Penicillins
Find the drug label by searching at DailyMed.

Generic drug name: ampicillin (am pi SILL in)
Brand name(s): OMNIPEN-N
GENERIC: available FAMILY: Penicillins
Find the drug label by searching at DailyMed.

Pregnancy and Breast-feeding Warnings [top]

Pregnancy Warning

No valid data are available for these drugs, as they were not tested properly in animal studies. Use during pregnancy only for clear medical reasons. Tell your doctor if you are pregnant or thinking of becoming pregnant before you take this drug.

Breast-feeding Warning

These drugs are excreted in human milk. Because of the potential for adverse effects in nursing infants, you should not take these drugs while nursing.

Safety Warnings For This Drug [top]

Antibiotic-Associated Diarrhea

Antibiotic-associated diarrhea (AAD) is quite common and its incidence varies from 5% to 20% of patients depending on which antibiotic they are taking, although practically all antibiotics have been associated with AAD. Fortunately, most cases are mild and self-limited, ending with the cessation of use of the offending antibiotic. The antibiotics most commonly associated with this mild form of AAD include ampicillin, amoxicillin, cephalosporins and clindamycin.[1] There have been studies in children or adults in which the use of prophylactic yogurt in people using antibiotics has significantly reduced the occurrence or severity of AAD.[2],[3] However, 10% to 20% of all patients who get AAD (0.5% to 4% of patients using antibiotics) will get the more severe form of AAD known as pseudomembranous colitis (see below). If you are taking any antibiotic and develop diarrhea after starting to use the drug, call your physician to discuss whether another antibiotic should be used and to discuss the need for rehydration due to the fluid loss from the diarrhea.

Pseudomembranous colitis has been reported with nearly all antibacterial agents and may range in severity from mild to life-threatening. Therefore, it is important to consider this diagnosis in patients who present with diarrhea subsequent to the administration of antibacterial agents.

Because antibiotic therapy has been associated with severe colitis, which may end fatally, it should be reserved for serious infections where less toxic antimicrobial agents are inappropriate, as described in the INDICATIONS AND USAGE section. It should not be used in patients with nonbacterial infections such as most upper respiratory tract infections. Treatment with antibacterial agents alters the normal flora of the colon and may permit over-growth of clostridia. Studies indicate that a toxin produced by Clostridium difficile is one primary cause of "antibiotic-associated colitis."

After the diagnosis of pseudomembranous colitis has been established, therapeutic measures should be initiated. Mild cases of pseudomembranous colitis usually respond to drug discontinuation alone. In moderate to severe cases, consideration should be given to management with fluids and electrolytes, protein supplementation, and treatment with an antibacterial drug that is clinically effective against C. difficile colitis.

Diarrhea, colitis, and pseudomembranous colitis have been observed to begin up to several weeks following cessation of therapy.

Facts About This Drug [top]

Amoxicillin (AMOXIL) is used to treat certain infections caused by bacteria, such as ear, sinus and bladder infections. It also is prescribed for bronchitis in people with chronic lung disease and for gonorrhea. A second drug, clavulanate, is sometimes combined with amoxicillin (AUGMENTIN is the brand name of the combination). Clavulanate helps amoxicillin work better by preventing bacteria from resisting the drug. Amoxicillin will not help a cold or the flu.

Amoxicillin is sometimes used...

Amoxicillin (AMOXIL) is used to treat certain infections caused by bacteria, such as ear, sinus and bladder infections. It also is prescribed for bronchitis in people with chronic lung disease and for gonorrhea. A second drug, clavulanate, is sometimes combined with amoxicillin (AUGMENTIN is the brand name of the combination). Clavulanate helps amoxicillin work better by preventing bacteria from resisting the drug. Amoxicillin will not help a cold or the flu.

Amoxicillin is sometimes used in combination with other drugs to treat ulcers caused by Helicobacter pylori. (See "Combination Treatments for Helicobacter Pylori Infection.")

Adverse effects

Tooth discoloration has been reported with amoxicillin use.

Ampicillin (OMNIPEN-N) is an older form of amoxicillin. Many people who take ampicillin develop a slight skin rash. This may or may not be a sign that the patient is allergic to the drug. If you get a skin rash, call your doctor. Some of ampicillin’s adverse effects can appear as late as a month after you stop taking it.

Patients with kidney disease should take less than the usual adult dose of amoxicillin. The excretion of crystals (small irregular solids) in the urine (crystalluria) producing urine irritation has been reported in these patients.[4]

Liver injury

In rare instances, liver injury has been reported in patients taking the combination of amoxicillin and clavulanate. The estimated risk of damage to the liver (hepatotoxicity), presumably due to this combination, increases from 3 to 17 per 100,000 prescriptions. Patients on prolonged or repeated courses of treatment and men over the age of 50 taking this combination are at an increased risk of developing hepatotoxicity.[5]

Although most patients recover with supportive care, hepatitis often does not occur until after the drug is stopped.[6],[7] Two cases of severe hepatotoxicity that rapidly progressed to life-threatening acute liver failure have been reported with the use of amoxicillin-clavulanate.[5]

Serious allergic reactions

Serious and occasionally fatal anaphylactic reactions have occurred in patients treated with amoxicillin.[8]

Severe skin adverse reactions

The combination drug amoxicillin-clavulanate may cause severe skin reactions, including Stevens-Johnson syndrome, toxic epidermal necrolysis and drug reaction with eosinophilia and systemic symptoms.[8]

In 2023, Journal of Chemotherapy published an article showing that amoxicillin and amoxicillin-clavulanate were associated with an increased risk of Steven-Johnson syndrome and toxic epidermal necrolysis.[9]

Interactions with other drugs

Co-administration of amoxicillin and the oral anticoagulation medication (blood thinner) warfarin (COUMADIN, JANTOVEN) showed an increased international normalized ratio (INR), a blood test for assessing warfarin drug levels. The test measures the time it takes for blood to clot. The higher the INR, the longer it takes for blood to clot. If the INR is too high, there is a risk of bleeding. The increased INR in this case suggests a risk of bleeding.

Studies show …

A 2005 study conducted to determine if antibiotics are beneficial in treating patients with sinusitis complaints and other related symptoms (pus in the nasal cavity, facial pressure or nasal discharge lasting longer than seven days) found that amoxicillin did not provide any significant benefits over a placebo. Although there were study patients whose symptoms did improve while on amoxicillin, identifying these patients in advance and treating them with antibiotics may be difficult in a clinical setting. Treating patients unnecessarily with antibiotics may result in potential harm to the patient.[10]

Another study published in 2012 found that amoxicillin was no better than placebo for relieving symptoms in patients with acute cold and sinusitis symptoms.[11]

Regulatory actions surrounding these drugs

2011: In November, the Food and Drug Administration (FDA) updated the drug product label for amoxicillin to include information on the use of amoxicillin and oral anticoagulant medications. The FDA stated that co-administration of amoxicillin and oral anticoagulant medications such as COUMADIN led to an increased INR.[12]

2022: The FDA updated the drug product label of amoxicillin to warn that amoxicillin can cause severe skin reactions.[13]

Before You Use This Drug [top]

Do not use if you have or have had:

  • allergy to penicillins
  • liver disease (for amoxicillin and clavulanate)

Tell your doctor if you have or have had:

  • allergies to drugs (see Types of Allergic Reactions in Penicillins and Cephalosporins)
  • history of allergies, such as asthma, eczema, or hay fever
  • stomach or intestinal disease
  • kidney disease
  • infectious mononucleosis
  • bleeding disorder
  • heart disease
  • cystic fibrosis
  • phenylketonuria (chewable tablets of amoxicillin and clavulanate)
  • diabetes (certain diabetes tests are affected)
  • pregnancy or are breast-feeding

Tell your doctor about any other drugs you take, including aspirin, herbs, vitamins, and other nonprescription products.

When You Use This Drug [top]

  • Check with your doctor if there is no improvement within a few days or if symptoms become worse.
  • If you get severe diarrhea, check with your doctor before taking any antidiarrheals.
  • If you plan to have any surgery, including dental, tell your doctor that you take this drug.
  • Possibly use an alternate or additional method of contraception if you are taking estrogen-containing oral contraceptives.
  • Caution diabetics: These drugs may interfere with glucose urine tests.

How to Use This Drug [top]

  • If you miss a dose, take it as soon as you remember, but skip it if it is almost time for the next dose. Do not take double doses.
  • Do not share your medication with others.
  • Take the drug at the same time(s) each day.
  • For ampicillin: Take the drug with water only. Do not eat or drink for about an hour before taking this medication.
  • Amoxicillin and amoxicillin with clavulanate may be taken with or without food.
  • Take this drug for the prescribed length of time. If you stop too soon, your symptoms could come back.
  • For tablets, store at room temperature with lid on tightly. Do not store in the bathroom. Do not expose to heat, moisture, or strong light. Keep out of reach of children.

Interactions with Other Drugs [top]

The following drugs, biologics (e.g., vaccines, therapeutic antibodies), or foods are listed in Evaluations of Drug Interactions 2003 as causing “highly clinically significant” or “clinically significant” interactions when used together with any of the drugs in this section. In some sections with multiple drugs, the interaction may have been reported for one but not all drugs in this section, but we include the interaction because the drugs in this section are similar to one another. We have also included potentially serious interactions listed in the drug’s FDA-approved professional package insert or in published medical journal articles. There may be other drugs, especially those in the families of drugs listed below, that also will react with this drug to cause severe adverse effects. Make sure to tell your doctor and pharmacist the drugs you are taking and tell them if you are taking any of these interacting drugs:

COUMADIN, GARAMYCIN, gentamicin, heparin, oral contraceptives, warfarin.

Adverse Effects [top]

Call your doctor immediately if you experience:

  • severe asthma (wheezing)
  • extreme weakness
  • nausea or vomiting
  • rash
  • fast or irregular breathing
  • puffiness or swelling around the face
  • shortness of breath
  • severe decrease in blood pressure
  • red, scaly skin
  • joint pain
  • fever
  • hives or itching
  • sore throat and fever
  • anxiety or confusion
  • depression
  • seizures
  • decrease in amount of urine
  • pain, cramps, or bloating in abdomen or stomach
  • severe, watery diarrhea (may contain blood)
  • dark urine
  • yellow eyes or skin
  • light-colored stools
  • loss of appetite
  • dizziness or headache
  • joint pain
  • unusual bleeding or bruising
  • vaginal itching or discharge (for amoxicillin and clavulanate)
  • swelling of face, fingers, or lower legs (for amoxicillin and clavulanate)
  • blistering, peeling, or loosening of skin (for amoxicillin and clavulanate)

Call your doctor if these symptoms continue:

  • mild diarrhea
  • nausea or vomiting
  • headache
  • white patches on mouth and/or tongue
  • vaginal itching or discharge
  • gas (for amoxicillin and clavulanate)
  • stomach pain (for amoxicillin and clavulanate)

Periodic Tests[top]

Ask your doctor which of these tests should be done periodically while you are taking this drug:

  • blood tests
  • stool exam
  • liver and kidney tests

last reviewed April 30, 2024