Beta Lactams

Amoxicillin, Amoxicillin combined with clavulanate, Penicillin V, Cloxacillin, Cephalexin and Cefuroxime belong to a group of medicines which are used to treat bacterial infection known as beta lactams.


​What is this medication used for​​

Beta lactams are a group of antibiotics used to treat infections caused by certain bacteria. These may include infections of the lung, urine, skin and soft tissue. 

Dosage and How to Use​​

  • You should complete each course of antibiotics even if you feel better as incomplete treatment might cause the infection to return or cause antibiotic resistance. When antibiotic resistance happens, the antibiotic will not be able to control the growth or kill the bacteria anymore.
  • Refer to the following table to find out when to take your medicine
​​Medicine​When to take
​Penicillin V, Cloxacillin​Half an hour to 1 hour before food
​Amoxicillin, Amoxicillin combined with clavulanate, Cefuroxime​With or after food
​Cephalexin​With or without food
  • If you miss a dose, take the missed dose as soon as you remember. If it is almost time for your next dose, skip the dose you missed and take your usual dose when you are supposed to. Do not double your dose or use extra medicine to make up for the missed dose.

Side Effects, Precautions, Contraindication​​​

What are the possible side effects of the medicines?​

Some common side effects that you may experience include

  • Mild diarrhoea
  • Stomach pain
  • Nausea or vomiting

Stop the medicine and see a doctor immediately if you have:

  • ​Serious diarrhoea that does not stop
  • Very loose or watery stools
  • Blood in your stools
  • Very bad stomach pain or cramps
  • Serious skin rash that looks red, swollen, blistered or peeling

Inform your doctor if you have a white, furry sore tongue and mouth or sore and itchy vagina with or without discharge. You might be having a fungal infection called thrush because of the antibiotic use.

How do I know if I am allergic to these medicines?​

The symptoms of a drug allergy include one or more of the following:

  • Swollen face/eyes/lips
  • Difficulty in breathing
  • ​​Itchy skin rashes over your whole body

If you experience any of these symptoms, you should stop your medicine immediately and see your doctor.

What precautions should I follow when taking the​ medicines?​

Before starting on these medicines, inform your doctor if you

  • ​Had a previous allergic reaction to amoxicillin, cloxacillin, penicillin, cephalexin, cefuroxime or other beta lactam antibiotics
  • Are pregnant or breastfeeding
  • Have kidney or liver problems
  • Are taking warfarin, a medicine to thin your blood
  • Are taking methotrexate, a medicine used to treat arthritis and some types of cancer
  • Are taking probenecid, a medicine used to treat gout

These medicines can affect the levels of other medicines in your body. Do let your doctor know what other medicines, including over-the-counter medicines, vitamins and herbal products you are taking before starting on your antibiotic.

Handling and Storage​​

  • Keep your medicines in the original container or packaging, tightly closed or sealed in a cool and dry place, away from direct sunlight.
  • Keep the medicine out of reach of children.
  • Throw away all expired medicines.

This article answers some common questions about this medicine. It does not contain all the available information. It also does not take the place of talking to your doctor or pharmacist.



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