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Amoxicillin is a penicillin-type (beta (β)-lactam class) antibiotic that fights bacteria in the body.

Last Modified: 22 May 2024

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What is Amoxicillin? 

Amoxicillin is a penicillin-type (beta (β)-lactam class) antibiotic that fights bacteria in the body. It is an analogue of ampicillin, derived from the basic penicillin nucleus, 6-aminopenicillanic acid. The formula is C16H19N3O5S·3H2O, and it comes as a white or almost white crystalline powder. 

Amoxicillin is produced by fermentation using the Penicillium mould, followed by specific steps to isolate and purify the active substance. 

Global Name

Generic Name and Brand Names 

  • Generic name: Amoxicillin 
  • Brand names: Amoxil, Trimox, Moxatag


What is Amoxicillin used for?

Amoxicillin is used to treat a wide variety of bacterial infections, including: 

  • Ear infections 
  • Throat infections (such as tonsillitis and pharyngitis) 
  • Upper respiratory infections 
  • Urinary tract infections 
  • Skin infections 
  • Helicobacter pylori infection (in combination with other medications) 
  • Dental infections 

How do you use Amoxicillin?


Amoxicillin is available as capsules, chewable tablets, and as a liquid suspension. 

Dosage information: 

  • Adults: 250 to 500 mg every 8 hours or 500 to 875 mg every 12 hours, depending on the severity of the infection. 
  • Children: Dosing varies based on weight and type of infection; refer to pediatric dosing guidelines. 

Suitable for: 

  • Children: Yes 
  • Adults: Yes 
  • Elderlies: Yes, with normal dosing but monitor kidney function. 
  • Pregnancy and Lactation: Amoxicillin is considered safe but should be used under medical advice. 

Who can't take Amoxicillin? 

  • Children: Neonates and infants with immature renal function should be dosed carefully. 
  • Adults: Those with severe renal impairment may require dose adjustment. 
  • Elderlies: No contraindication, but renal function monitoring is advised. 
  • Allergies: Not suitable for individuals allergic to penicillin or cephalosporin antibiotics. 

Warnings and precautions:

Use with caution in patients with a history of severe allergic reactions to beta-lactam antibiotics. 

Amoxicillin is usually taken with or without food, and the oral suspension should be shaken well before each use. 

Interactions and contraindications:

Amoxicillin should not be used in patients with mononucleosis due to the risk of rash. It may interact with other drugs like methotrexate and warfarin. 

Side Effects

Common side effects include nausea, vomiting, diarrhoea, and rash. Severe side effects may include anaphylaxis, Steven-Johnson syndrome, and Clostridium difficile-associated diarrhoea. 

Pharmacist Tips

  • Storage information: Store capsules and tablets at room temperature. Keep the oral suspension in the refrigerator, but do not freeze; discard any unused portion after 14 days. 
  • Handling instructions: Measure the liquid medicine carefully using the dosing syringe provided or with a proper dose-measuring spoon or medicine cup. 


Where is Amoxicillin available in Hong Kong?

Amoxicillin is a prescription medication that can be prescribed by healthcare providers.


Is Amoxicillin for purchase over the counter?

No, Amoxicillin requires a prescription from a healthcare provider.

Can Amoxicillin treat viral infections like the cold or flu?

No, Amoxicillin is not effective against viral infections and should not be used for such conditions.

Should you complete the full course of Amoxicillin even if symptoms improve?

Yes, it's important to finish the entire course as prescribed to fully eradicate the causative agent and prevent the development of microbial resistance.

How long does it take for Amoxicillin to work?  

Amoxicillin typically begins to work within a few days, but it may take longer to fully clear an infection; it's important to complete the full course of antibiotics as prescribed, even if symptoms improve before the medication is finished. 

This website provides content related to drug use and medicine for informational purposes only. It is not a substitute for professional medical advice, diagnosis, or treatment. Do not use the information on this website to diagnose or treat a health problem or disease without consulting a qualified healthcare provider. The website's owners and contributors are not liable for any repercussions, adverse effects, or consequences resulting from the use of any medication or information provided herein.

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