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Penicillin Fact Card

Penicillin refers to a group of medicines but the term is often used to refer to Benzylpenicillin or Phenoxymethylpenicillin.

Brand Names Benzylpenicillin - Penicillin G Phenoxymethylpenicillin -Penicillin V
Used For Benzylpenicillin: Throat infections, otitis media, cellulitis, pneumonia, meningitis Phenoxymethylpenicillin: Oral infections, tonsillitis, otitis media, cellulitis
Doseage The dose will vary depending on which type of penicillin is being used.
Side Effects Commoner side effects: Diarrhoea, joint pains, rashes Serious but rare side effects: Anaphylaxis (severe, life threatening allergic reaction), angioedema (swelling of the lips or face - seek emergency medical treatment should this occur)
Warnings Do not take if allergic to penicillins Avoid alcohol if suffering from an infection that is needing antibiotics
Pregnancy Not known to be harmful

The penicillium mould was discovered in 1928 at St Mary's Hospital in London by Sir Alexander Fleming; following almost 15 years of further study, Florey and Chain at Oxford managed large scale production of the medicine and it has been used to treat infections since 1942. The three scientists later shared the Nobel Prize in Medicine and physiology in 1945.

What is Penicillin used to treat?

Penicillin can treat a range of infections, varying in severity from common streptococcal infections of the face and throat to gonococcal and meningococcal infections as well as rarer conditions like anthrax, diptheria, gas-gangrene, leptospirosis and Lyme disease

How does Penicillin work?

Penicillin inhibit the ability of bacterium to build and maintain its cell walls, causing the bacterium to burst and die.

penicillin alcohol

How do I take Penicillin?

The dose that will be prescribed for an adult will vary based on likely diagnosis and perceived severity, but for a more common condition like tonsillitis the dose is 500mg to 1g, four times daily for a duration of 10 days.

For children the dose will vary based on the age of the child and the condition being treated.  You should always follow the dosage instructions that your doctor recommends.

Side effects of Penicillin

Anaphylaxis (severe, life threatening allergic reaction), occurs in a small proportion of the population and is generally over-reported as a whole - allergic reactions occur in between 1-10% of exposed individuals  but severe reactions in fewer than 1 in 2,000; rashes that appear more than 72 hours after the first dose are not likely to be due to allergy

Other side-effects of Penicillin include fever, angioedema (swelling of the lips or face - seek emergency medical treatment should this occur), joint pains and rashes

Rarer side-effects include blood clotting problems, reactions in the brain that can lead to seizures, reduced white cell counts and renal problems

Diarrhoea is not uncommon and occurs with many other antibiotics when taken orally 

penicillin side effects

Things to avoid

Those with penicillin allergy should avoid using any of the Cephalosporin antibiotics as there is an approximately 10% risk of a cross-reaction to these antibiotics.

Penicillin and alcohol

No overt contraindication but if unwell enough to require antibiotics, abstinence would be advisable.

penicillin when pregnant

Can I take Penicillin when pregnant?

Penicillin is not known to be harmful during pregnancy.

Penicillin and breastfeeding

Trace amounts of Penicillin can be found in breast milk but it is appropriate to use the drug when breast feeding.

penicillin when breastfeeding

Our doctors are available now and can issue same day prescriptions for all standard medications. To see a GP regarding a prescription for penicillin or for any other reason book an appointment now and start feeling better right away.

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Please note. This site is for information only. If you are taking any medications please follow the instructions given by your doctor. Should you have an adverse reaction to any medication please seek medical advice.

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