Amoxicillin: Indications, Recommended Dose & Side Effects

Amoxicillin is an antibiotic indicated for the treatment of various bacterial infections. It prevents the multiplication and growth of infectious bacteria, such as E. coli, Salmonella sp., Shigella sp., Neisseria gonorrhoeae and H. pylori. The dose of amoxicillin depends on the infection to be treated and the severity of the patient's symptoms, and should be prescribed by the doctor.

The side effects of amoxicillin are uncommon and usually temporary. They may include nausea, vomiting and diarrhea. It is important to inform your doctor about any allergies you may have to penicillin, as amoxicillin in this population can cause a serious allergic reaction.

Amoxicillin can only be purchased at the pharmacy with a prescription, under the generic name "Amoxicillin" or under the brand names Amoxil, Moxatag or Trimox.

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Indications for use

Amoxicillin is prescribed for:

  • Urinary tract infections, like pyelonephritis or cystitis 
  • Tonsil infections
  • Sinusitis
  • Vaginitis
  • Ear infections
  • Skin infections
  • Respiratory infections, like pneumonia or strep throat 
  • Joint injections
  • Gastrointestinal infections, like typhoid fever

This medication can also be prescribed to treat Lyme disease and to prevent heart infections from surgery. It is also commonly prescribed with other medications for the treatment of stomach ulcers. 

Recommended dose

The recommended dose of amoxicillin and the treatment schedule vary depending on the infection being treated. The treatment plan should always be prescribed by a doctor. In most cases, the general dosing is as following:

  • Adults and children over 40 kg: The recommended dose is 250 to 500 mg orally, 3 times a day. For more serious infections, the doctor may consider increasing the dose to 750 mg up to 1g every 12 hours.
  • Children under 40 kg: the dose should be prescribed by the pediatrician according to the type of infection present and the severity of the child's symptoms.

In people with kidney failure, the nephrologist can adjust the dose of the drug, as amoxicillin is eliminated mainly through the urine, which can worsen kidney symptoms.

Possible side effects

The side effects that may occur with amoxicillin are typically mild and temporary. They include nausea, vomiting, diarrhea, redness and itchy skin. 

Amoxicillin can cause severe allergic or anaphylactic reactions that require immediate medical attention. If you notice symptoms such as difficulty breathing, coughing, chest pain, a closed throat, swelling of the mouth, tongue or face, or hives, stop treatment immediately and proceed to the nearest emergency room.

Does amoxicillin reduce the effect of contraceptives?

There is no clear scientific evidence on the effect of amoxicillin on contraceptives. However, there are cases in which vomiting or diarrhea can occur, due to changes in the intestinal flora caused by the antibiotic. This can reduce the amount of hormones absorbed into the body.

Therefore, patients are advised to use other forms of contraceptives such as condoms when taking amoxicillin, and for up to 28 days after the end of treatment.

Contraindications for use

This antibiotic is contraindicated for patients with a history of allergy to betalactam antibiotics, such as penicillins or cephalosporins, and for patients with an allergy to amoxicillin or any of the components in the formula.

You should talk to your doctor before starting treatment if you are pregnant or breastfeeding, have kidney problems or are being treated with other drugs.