An injectable penicillin antibiotic active against Pseudomonas
Azlocillin
An injectable penicillin antibiotic used in hospital, particularly against Pseudomonas infections.
What is Azlocillin?
Azlocillin is an extended-spectrum penicillin antibiotic given by injection in hospital. It is used for serious bacterial infections, particularly those caused by Pseudomonas, a bacterium that can cause difficult infections in unwell or vulnerable people. Like all penicillins, its most important safety issue is allergy, which can range from a rash to a severe, life-threatening reaction (anaphylaxis), so anyone with a penicillin allergy must tell the team. It is given in hospital by a specialist team and is not a routine first-line antibiotic.
Education and reference only. This is a plain-language guide to Azlocillin — it deliberately contains no doses. Doses depend on the person, the brand and the reason for treatment, and belong with your prescriber. Always check the BNF, the product labelling (SmPC) and follow medical advice.
What it is
Azlocillin is an antibiotic from the penicillin family, specifically an extended-spectrum penicillin that is active against a wider range of bacteria than basic penicillins, including Pseudomonas. It is given by injection or infusion into a vein, in hospital, for serious infections. Because it targets harder-to-treat bacteria, it is used in specific situations rather than for everyday infections. As with all penicillins, allergy is the key safety concern, and it is always given under the supervision of a hospital team.
How it works
Azlocillin kills bacteria by interfering with the building of their cell wall, the protective layer that holds the bacterium together. Without an intact cell wall, the bacteria cannot survive and the infection is cleared. Its extended spectrum means it can reach bacteria, including Pseudomonas, that ordinary penicillins do not cover well. Because it works on the bacterial cell wall, which human cells do not have, it targets the bacteria while generally sparing the body's own cells, though allergic reactions can still occur.
Company & origin
Originated / developed by: Generic.
An extended-spectrum penicillin given by injection in hospital, used particularly for infections caused by the bacterium Pseudomonas; not a common first-line antibiotic in routine UK practice.
Practical use
How to take Azlocillin
General, dose-free guidance — always follow your prescriber's and the leaflet's specific instructions.
- It is given by injection or infusion into a vein by a hospital team, not taken by mouth at home.
- Tell the team straight away if you have ever had a reaction to penicillin or any antibiotic before it is given.
- Report any rash, itching, swelling, wheeze or feeling faint during or after treatment immediately.
- Complete the full course as prescribed, even if you feel better, to clear the infection.
- Tell the team if you develop diarrhoea, especially if it is severe or persistent.
Weighing it up
Advantages & disadvantages of Azlocillin
Advantages
- Active against a wider range of bacteria, including Pseudomonas, than basic penicillins.
- Useful for serious infections where harder-to-treat bacteria are involved.
- Works by a well-understood mechanism, attacking the bacterial cell wall.
Disadvantages
- Can cause allergic reactions, including severe, life-threatening anaphylaxis in people allergic to penicillin.
- Must be given by injection in hospital.
- Like other antibiotics, can cause stomach upset and diarrhoea, including C. difficile infection.
Practical use
Good to know
The most important thing to know about azlocillin, as with any penicillin, is the risk of allergy. Reactions can range from a mild rash to a sudden, severe, life-threatening reaction called anaphylaxis, so it is vital that anyone who has ever reacted to penicillin or a related antibiotic tells the team before it is given. It is given by injection in hospital, usually for serious infections such as those caused by Pseudomonas, rather than for everyday illnesses. Like other antibiotics, it can upset the stomach and occasionally cause diarrhoea, including a gut infection called C. difficile. Completing the full course as prescribed is important to clear the infection and help limit antibiotic resistance. The team will choose it based on the specific bacteria involved and your medical history.
Who should not take it / use with caution
- People who are allergic to penicillins must not receive it, as reactions can be severe.
- It is used with caution in people who have had reactions to related antibiotics such as cephalosporins.
- It is used with care, and with dose review, in people with kidney problems and in pregnancy, under specialist guidance.
Monitoring
- Watching closely for allergic reactions, especially when treatment is first given.
- Checking kidney function and salts during treatment, particularly with longer courses.
- Reviewing the response to treatment and watching for diarrhoea or other side effects.
Side effects
- Allergic reactions, from rash and itching to severe anaphylaxis.
- Nausea, stomach upset or diarrhoea, including, less commonly, C. difficile infection.
- Sometimes effects on blood counts, salts or liver tests, which the team monitors during treatment.
Key interactions
- It can interact with the gout medicine probenecid, which raises penicillin levels in the body.
- Like other penicillins, it may rarely affect how well some other medicines work, so tell the team everything you take.
- It is often combined carefully with other antibiotics for serious infections, guided by the team.
Available as: A powder made up into a solution for injection or infusion into a vein.
Answers
Azlocillin: frequently asked questions
What is azlocillin used for?
It is an extended-spectrum penicillin antibiotic given by injection in hospital for serious infections, particularly those caused by Pseudomonas.
Is it safe if I am allergic to penicillin?
No. Azlocillin is a penicillin, so people allergic to penicillin must not receive it because reactions can be severe and life-threatening.
Why is it given by injection?
It is used for serious infections in hospital and is given by injection or infusion into a vein by a specialist team.
Can it cause diarrhoea?
Yes, like other antibiotics it can cause stomach upset and diarrhoea, including, less commonly, a gut infection called C. difficile; tell the team if this happens.
Do I need to finish the course?
Yes. Completing the full course as prescribed helps clear the infection properly and limits the development of antibiotic resistance.
The wider class
About Penicillin antibiotic (extended-spectrum, anti-pseudomonal)
Azlocillin belongs to the penicillin antibiotic (extended-spectrum, anti-pseudomonal) class. For how the class as a whole works, its shared safety principles and monitoring, see the full guide.
Browse by body system
Authoritative sources
- BNF
- NICE CKS
Building a medicines information resource?
We create evidence-led, dose-free drug and formulary references for teams.