Meds and you

27 September 2013


Benzylpenicillin is a penicillin antibiotic. Penicillins are antibiotics that are derived from a mould. It is used to treat infections caused by harmful bacteria.


(Also known as Penicillin G)

Benzylpenicillin is the active ingredient of Benzatec (Nappi Code: 791016-005/008, 791032-019 & 791040-003), Benzyl Penicillin-Fresenius (Nappi Code: 782203-027 & 791334-015) and Bio-Pen (Nappi Code: 748307-001).

Benzylpenicillin is also one of multiple active ingredients found in Ultracillin (Nappi Code: 773581-006 & 773484-019).

General information Benzylpenicillin is a penicillin antibiotic. Penicillins are antibiotics that are derived from a mould. It is used to treat infections caused by harmful bacteria.

In South Africa benzylpenicillin is registered for the treatment of a wide range of bacterial infections caused by susceptible organisms including tonsillitis, pneumonia, meningitis, syphilis and soft tissue infections.

Should you develop a skin rash while being treated with this medication, you should notify your doctor to rule out the possibility of allergy.

A penicillin allergy may lead to fever, swelling of the mouth and tongue, itching and associated breathing difficulties.

Benzylpenicillin is only effective against bacterial infections, and is useless in treating viral infections such as cold or flu.

Antibiotic resistance occurs when a bacterium develops the ability to defend itself against the effect of an antibiotic. It occurs frequently with benzylpenillin. The most common cause of this is when patients do not complete the prescribed antibiotic courses (in case of oral penicillin) allowing the bacteria to recover from treatment. Another cause is when antibiotics are used to treat non-bacterial infections, such as cold and flu.

How does benzylpenicillin work?
Benzylpenicillin functions by changing the structure of the bacterial cell wall allowing fluid to penetrate into the cell. As a result the bacterial cell literally ruptures.

Fast facts

Drug schedule: schedule 4
Available as: benzylpenicillin is available as injection and as capsules
What does it do? benzylpenicillin has an antibiotic action
Overdose risk: low
Dependence risk: low
Is benzylpenicillin available as a generic? yes
Is benzylpenicillin available on prescription only? yes

User information

Onset of effect: within 2 hours
Duration of action: up to 8 hours
Stopping this medicine: complete the full course as prescribed by your doctor, even if you feel better within a few days. Premature discontinuation may cause symptoms to recur, or cause bacterial resistance,
Prolonged use: generally only given in short courses

Special precautions
Consult your doctor before using this drug if:


Pregnancy: avoid. It is unknown how this medication may affect your baby. Consult your doctor before using this drug, or if you are planning to fall pregnant
Breastfeeding: avoid. This medication is passed through breast milk and may affect your baby adversely. Consult your doctor before use.
Porphyria: this medication is safe to use.
Infants and children: this medication is safe for use in children at the recommended dose.
The elderly: no special precautions need to be taken.
Driving and hazardous work: no special precautions need to be taken.
Alcohol: no special precautions need to be taken.

Possible side effects

Side Effect
Consult your doctor
Only if severe
In all cases
nausea / vomiting
fungal infections
black/hairy tongue
skin rash
itchy skin
difficulty swallowing
loss of consciousness

Interactions Drug interactions


allopurinol increased risk of skin rash
chloroquine reduces the efficacy of antibiotic
oral contraceptives possibly reduces contraceptive efficacy. Another form of contraception is advised.
probenecid increased risk of antibiotic toxicity
tetracycline possible reduced antibiotic efficacy
warfarin increased risk of warfarin toxicity

Disease interactions
Consult your doctor before using this drug if you have a known allergy to penicillin or cephalosporin antibiotics, or if you have kidney or liver disease.

Overdose action
A small overdose is no cause for concern. In case of intentional large overdose, seek emergency medical attention.

Recommended dosage
Adults: 600 000 to 1 million units 6 hourly up to a maximum of 4 million units every 4 hours.


This material is not intended to substitute medical advice, but is for informational purposes only. Please consult a physician for specific treatment and recommendations.

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