How does this medication work? What will it do for me?

Amoxicillin belongs to the group of medications known as antibiotics, specifically to the family of antibiotics known as penicillins. It is used to treat infections caused by certain types of bacteria. It kills some types of bacteria that can cause infections of the ear, sinus, chest or lung, bone, bladder, and throat.

It may also be used to kill some types of bacteria that can cause infection in the stomach or small intestine, chlamydia (in pregnant and breast-feeding women), lyme disease, or typhoid fever (in children). Amoxicillin may also be used for prevention of infections that can be caused by certain dental or medical procedures.

Your doctor may have suggested this medication for conditions other than those listed in these drug information articles. As well, some forms of this medication may not be used for all of the conditions discussed here. If you have not discussed this with your doctor or are not sure why you are taking this medication, speak to your doctor. Do not stop taking this medication without consulting your doctor.

Do not give this medication to anyone else, even if they have the same symptoms as you do. It can be harmful for people to take this medication if their doctor has not prescribed it.

What form(s) does this medication come in?

This medication is available as 250 mg and 500 mg capsules.

This medication is available as 125 mg/5 mL and 250 mg/5 mL liquid suspensions.

How should I use this medication?

The recommended adult dose of amoxicillin varies widely depending on the age group and the condition being treated, but the medication is usually taken in 3 daily doses, once every 8 hours. Amoxicillin can be taken with or without meals.

Finish all this medication, even if you have started to feel better.

For the liquid form of amoxicillin, use an oral syringe to measure each dose of the liquid, as it gives a more accurate measurement than household teaspoons.

Many things can affect the dose of a medication that a person needs, such as body weight, other medical conditions, and other medications. If your doctor has recommended a dose different from the ones listed here, do not change the way that you are taking the medication without consulting your doctor.

It is important to take this medication exactly as prescribed by your doctor. If you miss a dose, take it as soon as possible and continue with your regular schedule. If it is almost time for your next dose, skip the missed dose and continue with your regular dosing schedule. Do not take a double dose to make up for a missed one. If you are not sure what to do after missing a dose, contact your doctor or pharmacist for advice.

Store this medication at room temperature, protect it from light and moisture, and keep it out of the reach of children.

Do not dispose of medications in wastewater (e.g. down the sink or in the toilet) or in household garbage. Ask your pharmacist how to dispose of medications that are no longer needed or have expired.

Who should NOT take this medication?

Amoxicillin should not be taken by anyone who:

  • is allergic to amoxicillin or to any of the ingredients of the medication
  • is allergic to the class of antibiotics called cephalosporins

What side effects are possible with this medication?

Many medications can cause side effects. A side effect is an unwanted response to a medication when it is taken in normal doses. Side effects can be mild or severe, temporary or permanent. The side effects listed below are not experienced by everyone who takes this medication. If you are concerned about side effects, discuss the risks and benefits of this medication with your doctor.

The following side effects have been reported by at least 1% of people taking this medication. Many of these side effects can be managed, and some may go away on their own over time.

Contact your doctor if you experience these side effects and they are severe or bothersome. Your pharmacist may be able to advise you on managing side effects.

  • abdominal pain (mild)
  • diarrhea (mild)
  • headache
  • loss of appetite
  • nausea
  • sore mouth
  • swollen tongue or black "hairy" tongue
  • vomiting

Although most of these side effects listed below don't happen very often, they could lead to serious problems if you do not check with your doctor or seek medical attention.

Check with your doctor as soon as possible if any of the following side effects occur:

  • abdominal pain (severe)
  • any new infection
  • bruising
  • dizziness
  • fever
  • nosebleeds
  • shortness of breath
  • skin rash, hives, or itching
  • symptoms of liver damage (e.g., yellow skin or eyes, abdominal pain, dark urine, clay-coloured stools, loss of appetite)
  • unusual tiredness or weakness

Stop taking the medication and seek immediate medical attention if any of the following occur:

  • convulsions (seizures)
  • diarrhea (watery and severe), which may also be bloody
  • symptoms of a serious allergic reaction (e.g., swelling of the face or throat, difficulty breathing, wheezing, or itchy skin rash)

Some people may experience side effects other than those listed. Check with your doctor if you notice any symptom that worries you while you are taking this medication.

Are there any other precautions or warnings for this medication?

Before you begin using a medication, be sure to inform your doctor of any medical conditions or allergies you may have, any medications you are taking, whether you are pregnant or breast-feeding, and any other significant facts about your health. These factors may affect how you should use this medication.

Allergy: Amoxicillin is a penicillin and should not be used by anyone with a penicillin allergy or an allergy to the class of medications called cephalosporins. People who have allergies in general should watch carefully for any reaction to amoxicillin when starting a new prescription. In rare cases, some people may develop a serious allergic reaction to this medication. Signs of an allergic reaction include a severe rash, hives, swollen face or throat, or difficulty breathing. If these occur, seek immediate medical attention.

Birth control: Penicillins may decrease the effectiveness of birth control pills. Some doctors recommend adding another method of birth control for the rest of the cycle when penicillin is taken.

Diarrhea: This medication is associated a serious infection called Clostridium difficile-associated diarrhea, caused by the bacteria C. difficile. This can occur even after your last dose of this medication. If you have severe diarrhea (with or without fever or blood) after taking amoxicillin, get medical attention as soon as possible.

Kidney disease: People with kidney disease should discuss with their doctor how this medication may affect their medical condition, how their medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed.

Medical conditions: When amoxicillin is used by a person who has mononucleosis, acute lymphocytic leukemia (a type of cancer that affects white blood cells), or cytomegalovirus infection (a viral infection), a widespread rash may occur. Talk to your doctor if you have any concerns.

Overgrowth of organisms: Treatment with any penicillin may allow normal fungus or types of bacteria not killed by the antibiotic to overgrow, causing unwanted infections such as yeast infections, which may cause vaginal itching and irritation. Women may prevent yeast infections by eating yogurt daily while taking this antibiotic. Talk to your doctor if you have any concerns.

Pregnancy: This medication should not be used during pregnancy unless the benefits outweigh the risks. If you become pregnant while taking this medication, contact your doctor immediately.

Breast-feeding: This medication passes into breast milk. If you are a breast-feeding mother and are taking amoxicillin, it may affect your baby. Talk to your doctor about whether you should continue breast-feeding.

What other drugs could interact with this medication?

There may be an interaction between amoxicillin and any of the following:

  • BCG vaccine
  • birth control pills
  • fusidic acid
  • methotrexate
  • probenecid
  • tetracyclines (e.g., minocycline, doxycycline)
  • typhoid vaccine

If you are taking any of these medications, speak with your doctor or pharmacist. Depending on your specific circumstances, your doctor may want you to:

  • stop taking one of the medications,
  • change one of the medications to another,
  • change how you are taking one or both of the medications, or
  • leave everything as is.

An interaction between two medications does not always mean that you must stop taking one of them. Speak to your doctor about how any drug interactions are being managed or should be managed.

Medications other than those listed above may interact with this medication. Tell your doctor or prescriber about all prescription, over-the-counter (non-prescription), and herbal medications you are taking. Also tell them about any supplements you take. Since caffeine, alcohol, the nicotine from cigarettes, or street drugs can affect the action of many medications, you should let your prescriber know if you use them.