Amoxicillin (Oral)

Amoxicillin antibiotic is administered orally and is used to fight bacteria and bacterial infections.


Amoxicillin works by killing bacteria in the body and stopping their growth. It is often used as part of a treatment regime with other medicines which may include additional antibiotics. This drug is available in the following dosage forms:

  • Capsule
  • Powder for suspension
  • Tablet, extended release
  • Tablet, chewable
  • Tablet
  • Tablet for suspension

The tablet form comes in immediate release (IR), extended release (ER), and chewable tablets. IR and chewable amoxicillin tablets are available as generics. The generic names do not come in the same strengths and forms as the brand names.

ER tablet is available only under the brand name Moxatag. Amoxicillin is also available as a capsule and as an oral suspension. It is a prescription-only medication.

It is available in Canada under the following brand names:

  • Amoxil Pediatric
  • Apo-Amoxi
  • Gen-Amoxicillin
  • Novamoxin
  • Zimamox
  • Novamoxin Reduced Sugar
  • Scheinpharm Amoxicillin
  • Nu-Amoxi
  • Med Amoxicillin
  • Apo-Amoxi Sugar-Free
  • Riva-Amoxicillin

In the U.S., amoxicillin is available under the following brand names:

  • Moxatag
  • Amoxicot
  • Moxilin
  • Amoxil
  • Trimox
  • DisperMox

Amoxicillin belongs to the therapeutic class, antibiotic and the pharmacological class, Penicillin, Aminopenicillin. It is an FDA approved drug. The first approval for an amoxicillin formulation was issued on December 9, 1974.

Conditions Treated

  • Infections of the nose, ear, and throat
  • Genitourinary tract infections
  • Skin structure and other skin infections
  • Lower respiratory tract infections
  • Infection with Helicobacter pylori

Type of Medicine

  • Antibiotic

Side Effects

Many drugs have other effects other than what is desired. Each drug has its list of commonly seen side effects. Side effects will not necessarily be seen in all patients, even those frequently observed.

The frequency of the following side effects seen with amoxicillin is not known, but a doctor should be immediately notified if they are observed.

  • Tenderness and cramps in the stomach and abdominal area
  • Pain in the leg, back, and abdomen
  • Passing stool that is black and tarry or clay-colored
  • Loosening, peeling, and blistering of the skin
  • Bleeding gums
  • Bloody nose and urine
  • Bloating
  • Coughs and chest pain
  • Chills
  • Urine may become dark colored
  • Diarrhea, at times very watery and severe, and that may at times contain blood
  • Trouble breathing and swallowing
  • Racing heart
  • Dizziness
  • Fever
  • Feeling uncomfortable
  • A patient may notice their body is swelling
  • Heavy flow of menstrual blood
  • Headache
  • Welts or hives
  • Increased thirst
  • Itching
  • Aches and pain in the muscles
  • Inflammation and pain in the joints
  • Appetite loss and at times nausea or vomiting
  • Pain
  • Nose bleeding
  • Lower back pain
  • Difficult or painful urination - there may also be a reduction in the amount of urine passed.
  • Pale skin
  • The patient's skin may develop red pinpoint spots - it may also become sore and itchy.
  • Swellings or puffiness around the eyes, eyelids, tongue, face or lips
  • Rash
  • The eyes could also become irritated and redden
  • Sore throat
  • Shortness of breath
  • The patient's mouth or lips may develop white spots, ulcers or sores
  • Blisters, welting, or sores may form on the patient's body
  • The lymph glands may swell
  • Tenderness may be felt in various parts of the body
  • A feeling of tightness may be felt in the chest
  • The patient's breath may develop a bad odor
  • There may be bruising and bleeding which is not usual
  • The patient may experience weight loss which is unusual
  • Vomiting of blood may be observed
  • The patient's skin and eyes may yellow
  • Wheezing

Other side effects of amoxicillin are not severe and do not require the immediate attention of a medical professional. However, a healthcare provider may be able to advise on how to minimize their effect or prevent them. These effects go away as soon as the body adjusts to the medication.

The following are two of these effects. These are rarely seen:

  • Change in taste
  • Having a bad, unpleasant aftertaste in the mouth

The incidence of the following is not known, but they are also seen:

  • Confusion, convulsions and behavior changes. Agitation is also observed at times.
  • The tongue may darken to a blackish color and become hairy
  • Some teeth may get a gray, yellow, or brown discoloration
  • The patient may begin to have trouble with sleeping and experience a lot of sleeplessness and difficulty sleeping
  • Dizziness
  • White patches may appear with diaper rash, or on the tongue, in the throat or mouth


The dosages suggested here are not to be used for prescribing amoxicillin drugs. Only a physician or other trained healthcare professional has the expertise to decide on dosage for each case:

  1. Adult Dose for Endocarditis Prophylaxis caused by Bacteria

American Heart Association, (AHA) recommends the following dosages for this condition: 2g of immediate release medicine, administered orally, 30 to 60 minutes before the procedure.

  1. Chlamydia infection Adult Dose

U.S. CDC recommends that amoxicillin is used as an alternative to azithromycin in pregnant women. 500mg should be administered orally, three times a day for seven days.

Women who run a higher risk of contracting Chlamydia and those younger than 25 years should be screened for infection in the third trimester to prevent the infant getting a chlamydial infection or the mother developing postnatal complications.

  1. Adult dosages for infection by Helicobacter pylori

Triple therapy

Lansoprazole and Clarithromycin are administered in this treatment combined with amoxicillin. Every 12 hours, 1g is given orally of amoxicillin together with the other two drugs.

Dual therapy

Lansoprazole is administered together with amoxicillin in this treatment. 1g of amoxicillin should be given every eight hours for 14 days alongside Lansoprazole.

Lansoprazole and Clarithromycin should be referenced for full prescribing information.

  1. Dosages for adults with Lyme disease-Arthritis

The Infectious Diseases Society of America (IDSA) recommends 500mg should be administered orally, thrice daily, 14 to 28 days.

The period of treatment will be determined by the severity of the condition. Currently available guidelines should be consulted for in-depth information on dosing for this state.

  1. Dosages for adults with Lyme diseases - Carditis

IDSA recommendations are 500mg administered orally three times a day for 14 to 28 days.

The number of days the patient will receive this treatment will be determined by the severity of the condition. Current guidelines should be consulted for in-depth information on dosing for this state.

  1. Dosage for Adults with Lyme disease - Erythema Chronicum Migrans

IDSA recommends 500mg of amoxicillin should be administered three times a day for between 14 to 28 days depending on the severity of the condition being treated. Current guidelines should be consulted on information on dosing for this disease.

  1. Dosing for adults with Lyme disease

IDSA recommends 500mg should be administered three times a day for a period of 14 to 28 days depending on the severity of the condition being treated. Current guidelines should be consulted for more information on dosing for this disease.

  1. Dosage for adults with Pneumonia

To treat infections of the respiratory tract, lower side arising from susceptible isolates of the Streptococcus species, Staphylococcus species, H. influenzae, and S. pneumoniae, apply the following doses every eight hours, 500mg administered by mouth or 875mg every 12 hours. This should be immediate release forms of amoxicillin, and dosages are irrespective if the severity of the disease.

American Thoracic Society (ATS) and IDSA recommend that pneumonia should be treated with 1g of immediate release form of amoxicillin administered orally three times each day.

Amoxicillin can be used in combination with other drugs to treat pneumonia.

Therapy for pneumonia should be discontinued if:

  • The patient has received medication for a minimum of 5 days.
  • Has been afebrile for between 48 to 72 hours.
  • Has at most one CAP (community-acquired pneumonia) associated sign of instability, measurable clinically.
  1. Dosage for adults with Bronchitis

The dosages are the same as above for pneumonia.

  1. Dosages for adults with Sinusitis and urinary tract infections

For mild to moderate infections: administer orally 250mg every eight hours or 500mg every 12 hours.

For severe infections: administer 500mg by mouth taken every eight hours or 875mg every 12 hours.

  1. Adult dose for Pharyngitis/tonsillitis

The extended-release form of amoxicillin should be used for this treatment.

775mg each day administered orally within an hour of taking a meal. Dosing should continue for 10 days.

The 10 days course of treatment must be completed for the treatment to be effective.

IDSA recommends 1000mg of amoxicillin taken orally once daily or 500mg given twice a day.

  1. Dosages for adults with infections of the skin and its structure

Mild to moderate infections: 250mg of amoxicillin swallowed every eight hours or 500mg every 12 hours. Immediate release drugs should be used for this treatment.

Severe infections: 500mg swallowed every eight hours or 875mg every 12 hours.

IDSA recommendations: 500mg taken orally twice every day for seven to 10 days.

  1. Dosage for adults with Cutaneous Bacillus Anthracis and Anthrax prophylaxis

U.S. CDC recommends 1g should be administered by mouth every eight hours. Prophylaxis duration is 60 days.

Pediatric Dosages

This drug has been found safe for children at doses which are prescribed by a doctor according to the child's weight.


57 drugs, 441 generic and brand names interact with amoxicillin. Four drugs, 14 generic and brand names have major interactions with amoxicillin. 47 drugs, 368 generic and brand names have moderate interactions with amoxicillin. 16 drugs, 59 generic and brand names have minor interactions with amoxicillin.

Major interactions imply that such interactions are highly clinically significant, and the risks of using such two drugs together exceed the benefits.

Moderate interactions infer that such interactions are clinically significant to a certain degree, and should, therefore, be used together only in exceptional circumstances. Combinations are to be avoided.

Minor interactions imply that the interactions are clinically significant to a small extent, and alternatives should be sought. Such drugs, however, can be used together only if measures are taken to circumvent the risk of interactions, or a monitoring plan is put in place.

The following drugs have major interactions with amoxicillin:

  • Cholera vaccine, live
  • Methotrexate LPF Sodium (methotrexate)
  • Folex PFS (methotrexate)
  • Otrexup (methotrexate)
  • Rheumatrex Dose Pack (methotrexate)
  • Methotrexate
  • Trexall (methotrexate)
  • Vaxchora (cholera vaccine, live)
  • Rasuvo (methotrexate)
  • Xatmep (methotrexate)

Disease interactions

Amoxicillin has six disease interactions, namely:

  • Colitis
  • Renal Dysfunction
  • Hemodialysis
  • Mononucleosis
  • Diabetes
  • PKU

It is important to note that the above information on drug interactions of amoxicillin is not complete. Since drugs interact differently in different individuals, it is not possible to note down all potential interactions. Some medicines are known to cause amoxicillin to be less effective and should be used with caution when taking this drug.

A doctor should be notified of all medications that a patient is using and all symptoms that arise in the course of treatment to be able to determine the appropriate course of action.


If symptoms do not improve after using this medicine for a few days, a doctor should be notified.

Amoxicillin can cause a very severe and life-threatening condition called anaphylaxis. Immediate medical attention should be sought if the following symptoms of anaphylaxis are observed after taking amoxicillin:

  • Shortness of breath
  • Skin rash
  • Itching
  • Trouble swallowing or breathing
  • Swelling of the throat, mouth, face or hands

A doctor should be notified if a patient taking amoxicillin is to undergo some tests. This drug may interfere with the results of specific tests. For instance, people with diabetes may get a false positive reaction after tests for sugar levels in urine.

Amoxicillin makes birth control medication ineffective. Condoms, diaphragms with spermicide or other methods of non-hormonal contraception should be used to avoid pregnancy when this drug is in use.

People with kidney disease should inform the doctor before getting a prescription for amoxicillin. In the case of renal trouble, the kidneys will not clear this drug quickly from the body, necessitating a dose adjustment.

Amoxicillin may cause diarrhea which could be severe, two or more months after stopping the use of the drug. If this happens, medical advice should be sought, as getting over the counter medications may make the problem worse.

In young patients, using this medicine may cause teeth to become discolored. The teeth may appear to have grey, yellow, or brown stains. To avoid this discoloration, brushing and flossing of teeth should be carried out regularly, or a visit made to a dentist for teeth cleaning.

Pregnancy Warnings

This drug is recommended for use during pregnancy if the benefits of using it outweigh the risks, and a doctor determines that the medication is needed. There are no studies on animals or humans that show any threat to a fetus when this drug is used.

Breastfeeding Warnings

Amoxicillin is considered safe to use during breastfeeding, but caution should be exercised. It is excreted in human milk in small amounts. The small quantities that pass into human milk are unlikely to do a baby any harm. In rare cases, it has been seen to disrupt the nursing babies gut flora, causing thrush and diarrhea.


This drug should be kept away from children and pets.

Medicine that has expired should be disposed of according to the advice of a medical professional.

The tablet form of this medicine should not be frozen, but stored in a closed container at room temperature, away from direct light, heat, and moisture.

The oral liquid form of this medicine can be stored in the refrigerator. Any medication not used after 14 days should be discarded safely.


Amoxicillin is an antibiotic that is effective against a wide array of bacteria but must be used according to a doctor's advice for it to be effective. A treatment course must be completed as advised by a doctor since taking antibiotics and stopping midway can result in bacteria developing resistance to the particular drug.

This drug should not be bought over the counter as that increases the risk of medicating oneself incorrectly. A doctor should always be consulted so that they can assess the risk of giving a particular antibiotic versus the good it will do. It is important to note that misuse of these medicines can affect the gastrointestinal flora, as the drugs may kill bacteria that are beneficial to the patient.

No information that a patient can collect anywhere should replace the medical advice of a trained healthcare professional. A patient must work closely with their doctor for the treatment they are receiving to be successful. Other over the counter products such as vitamins, minerals, and other natural products should not be purchased and added to the treatment regimen a patient is receiving without notifying a doctor. Some medications affect the efficacy and effectiveness of amoxicillin and only a trained healthcare professional can determine what is safe to use with this drug.

The information provided in this article is in no way complete, and neither is it meant to replace the advice of a doctor. Always consult a medical professional when needing treatment.

Last Reviewed:
December 26, 2017
Last Updated:
April 02, 2018