AMOXICILLIN (Amoxil): What is used for?

What is Amoxicillin?

Amoxicillin is a drug used for the treatment of various bacterial infections: tonsillitis, otitis, bronchitis, cystitis, endocarditis, meningitis, Lyme disease or Lyme borreliosis. The product ingredients are: Amoxicillin sodium, Amoxycillin trihydrate.

The brand names of Amoxicillin in the United States are: Amoxil, Moxatag.

Amoxicillin Mechanism of Action (MOA)

Bactericide. Inhibits the action of peptidases and carboxypeptidases preventing the synthesis of the bacterial cell wall.

Therapeutic indications, uses and benefits of Amoxicillin

  • Infections caused by sensitive strains such as: throat, nose and ear infections (tonsillitis, otitis media, sinusitis).
  • Infections of the lower respiratory tract (acute and chronic bronchitis, bacterial pneumonias).
  • Infection of the genitourinary tract without urological complications (cystitis and urethritis).
  • Infections of the skin and soft tissues (including surgical wound infections).
  • Infection in odonto-stomatology.
  • Infections of the biliary tract.
  • Lyme disease or Lyme borreliosis: in the treatment of localized early infection (first stage or localized erythema migratory) and disseminated infection or second stage.
  • Typhoid and paratyphoid fevers (especially indicated for the treatment of chronic biliary carriers).
  • Eradication treatment of Helicobacter pylori in association with PPI and other antibiotics: peptic ulcer and gastric lymphoma of lymphoid tissue associated with mucosa, low grade.
  • Prophylaxis of endocarditis produced by post-dental manipulation/extraction bacteremia.
  • Treatment and prophylaxis of septicemia, endocarditis, meningitis, pyelonephritis and certain neuropathies.

Amoxicillin Dosage

– Intravenous

Adults: 50-200 mg/kg/day; max. 12 g/day. Pulmonary, post-surgical, genitourinary and pyelonephritis infection: 1 g/6-8 h.
Septicemia, endocarditis: 1 g/4 h or 2 g/8 h, in perfusion.
Renal insufficiency: Clcr 30-60 ml/min: 2-4 g/day; Clcr 10-30 ml/min: 1 initial g, followed by 0.5 g/12 h; Clcr < 10 ml/min: 1 initial g, followed by 0.5 g/24 h.
Children: 25 mg/kg/6 h.
Severe infection: 50 mg/kg/6 h, perfusion.

– Oral

Adults and children > 40 kg: 1.5-3 g/day in equivalent doses; max. 6 g/day. Lyme disease, stage 1: 4 g/day, 10-21 days; stage 2: 6 g/day, 10-30 days.
H. pylori infection: 750 mg-1 g, 2 times/day, associated with other antibiotics and proton pump inhibitor, 7 days.
Simple cystitis in women: 3 g single dose.
Kidney failure: Clcr 10-30 ml/min: max. 500 mg 2 times/day; Clcr < 10 ml/min: max. 500 mg/day; haemodialysis: 15 mg/kg/day single dose + additional dose; peritoneal dialysis: max. 500 mg/day.

Children < 40 kg: 20-40 mg/kg/day in equivalent doses, max. 150 mg/kg/day.
Lyme disease: 25-50 mg/kg/day in early stage (10-21 days) and 100 mg/kg/day in late stage (10-30 days); min. 12 days.
Kidney failure: Clcr 10-30 ml/min: 15 mg/kg 2 times/day (max. 500 mg 2 times/day); Clcr < 10 ml/min: 15 mg/kg/day single dose (max. 500 mg/day).
Endocarditis prophylaxis: ads. 3 g 1 h before dental manipulation and second dose at 6-8 h if necessary.
Children < 10 years: ½ doses ads; children < 5 years: ¼ doses adults.

Method of administration of Amoxicillin

  • Parenteral treatment may be started according to the dose recommendations for the parenteral formulation and continued with an oral formulation.
  • For capsules: swallow with water without opening the capsule.
  • Coated tablets: swallow with water.
  • Dispersible tablets: suspend in water to drink or take directly with a sufficient amount of water (can be split to facilitate swallowing).

Contraindications of Amoxicillin

  • Hypersensitivity to ß-lactams.
  • History of an immediate severe hypersensitivity reaction (e.g. anaphylaxis) to another ß-lactamic agent (e.g. cephalosporin, carbapenem or monobactam).

Warnings and Cautions with Amoxicillin

Kidney failure, dose adjustment; monitoring liver function in patients with liver dysfunction.
Foresee possible anaphylactic reaction, in case of allergic reaction, interrupt administration and institute supportive or emergency treatment.
Risk of: convulsions in patients with altered renal function, with a history of convulsions, with treated epilepsy or with disorders of the meninges or at high doses.
Suspend treatment if generalized febrile erythema associated with pustules appears; risk of Jarisch-Herxheimer reaction after treatment of Lyme disease and overgrowth of non-sensitive microorganisms in prolonged treatment (reported cases of colitis, discontinue treatment if appears).
In prolonged treatment carry out periodic evaluation of organic functions (renal, hepatic and haematopoietic).
With high doses, maintain adequate fluid intake and diuresis to reduce the risk of crystalluria; monitor prothrombin time or INR concomitantly with anticoagulants and adjust its dose if necessary.
Avoid treatment in case of infectious mononucleosis.

Liver failure

To monitor liver function in patients with liver dysfunction.

Kidney failure

Caution. Adapt dose according to Clcr.

Interactions with Amoxicillin

  • Increases possibility of skin rash with: allopurinol.
  • Antagonism with: bacteriostatic antibiotics (chloramphenicol, tetracyclines, erythromycins, sulfonamides).
  • Tubular secretion decreased by: probenecid.
  • Decreases effectiveness of: oral contraceptives (use non-hormonal method).
  • Decreased absorption by: antacids.
  • Accelerated chemical inactivation by: alcohol intake.
  • Increases concentrations of: methotrexate.
  • Lab: false + urine glucose with chemical methods (use enzymatic methods), interferes in the determination of uric acid, blood proteins and Coombs test, distorts results of estriol analysis in pregnant women.

Pregnancy and Amoxicillin

Assess risk/benefit. Limited human data do not indicate an increased risk of congenital malformations.


Amoxicillin is excreted by human milk in small amounts with a possible risk of sensitization.
Therefore, diarrhoea and fungal infection of the mucous membranes may occur in the infant and breastfeeding may have to be discontinued.
Amoxicillin should only be administered during lactation after the benefit/risk has been assessed by the physician.

Effects on driving ability

No studies have been conducted on the ability to drive and use machines.
However, adverse effects may occur (e.g. allergic reactions, dizziness, convulsions), which may affect the ability to drive and use machines.

Adverse reactions and side effects of Amoxicillin

Diarrhea, nausea; skin rashes.
Reaction to drugs with eosinophilia and systemic symptoms (DRESS) has also been identified.


Source: The content of this active ingredient has been written taking into account the clinical and molecular information of all medicines authorised and marketed in the United States under the Unique Ingredient Identifier (UNII) by the Substance Registration System (SRS) of the Food and Drug Administration (FDA) and the United States Pharmacopeia (USP).

In order to know in detail the information authorized by the FDA for each drug, you should consult the corresponding medication guide authorized by the FDA.


UNII: 804826J2HU
PubChem CID: 62883
NCI Thesaurus: C237


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