Anti-infective
Macrolide antibiotics
e.g. clarithromycin, azithromycin — Common antibiotics for respiratory and other infections, and an option in penicillin allergy.
Education and reference only. This is a plain-language class overview — it deliberately contains no doses. Always check the current Summary of Product Characteristics (SmPC), the BNF and your local formulary before prescribing or administering any medicine.
What it is
Macrolides are a class of antibiotics used for respiratory tract, skin and some atypical infections. They are a common alternative for patients who are allergic to penicillin.
How it works
They bind the bacterial ribosome and stop the bacterium making proteins, halting its growth. They are active against many of the organisms that cause community respiratory infections.
In practice
In practice macrolides are a frequent choice for chest and soft-tissue infections and a useful alternative when someone is allergic to penicillin. Their big caveat is interactions: they inhibit a major drug-metabolising enzyme, raising the levels of drugs such as some statins, and they can prolong the QT interval — so check the QT and the medication list, especially in those already on QT-prolonging drugs.
Examples
Practical use
How to take it & use it well
- Take macrolide antibiotics such as clarithromycin or azithromycin exactly as prescribed and finish the full course, even if you feel better.
- Try to space doses evenly through the day and take them at around the same times.
- Some are better taken with food to reduce stomach upset; check the leaflet or ask your pharmacist.
- If you miss a dose, take it as soon as you remember unless the next is nearly due, then skip it; do not double up.
- Tell your prescriber about all your other medicines first, as macrolides interact with many drugs.
- Complete the course as directed rather than stopping early, to give the best chance of clearing the infection.
Common uses
- Respiratory tract infections
- Skin and soft-tissue infections
- Atypical infections; alternative in penicillin allergy
Monitoring
- Interacting medicines before prescribing
- QT interval where risk factors exist
- Response to treatment
Weighing it up
Advantages & disadvantages
Advantages
- They treat a range of common chest, throat, skin and other bacterial infections.
- They are a useful alternative for people who are allergic to penicillin.
- Some, such as azithromycin, are taken as a short course, which is convenient.
- They are effective against certain bacteria that other antibiotics do not cover well.
- They come in liquid and tablet forms, making them suitable across different ages.
Disadvantages
- They commonly cause nausea, stomach cramps, diarrhoea and an altered sense of taste.
- They can affect the heart's rhythm, which matters for people with certain heart conditions.
- They interact with a large number of other medicines, so a careful check is needed.
- Like all antibiotics, overuse contributes to resistance, so they should only be used when truly needed.
- They are not effective against viral illnesses such as colds and most sore throats.
Key safety principles
What to watch for
- Notable drug interactions — they raise levels of several drugs (e.g. some statins should be paused or switched).
- QT-interval prolongation — caution with other QT-prolonging drugs.
- Gastrointestinal upset is common, especially with erythromycin.
Key interactions
What to avoid or check alongside
- Certain statins for cholesterol can build up to harmful levels with some macrolides, raising the risk of muscle damage.
- Combining them with other medicines that affect heart rhythm can increase the risk of a dangerous rhythm change.
- They can raise the effect of blood thinners, increasing bleeding risk, so extra monitoring may be needed.
- They can increase levels of some medicines used for migraine, epilepsy and certain heart conditions.
- Indigestion remedies containing aluminium or magnesium can affect absorption of some macrolides if taken together.
- Always share a full medicines list, including herbal and over-the-counter products, before starting one.
Patient & carer advice
- Tell us all your other medicines, including over-the-counter ones
- Report palpitations or fainting
- Complete the course as advised
Use with
Related clinical calculators
Dose and risk decisions for this class often depend on renal function, weight or bleeding/stroke risk. These tools help:
Answers
Macrolide antibiotics: frequently asked questions
Can I take a macrolide if I am allergic to penicillin?
Often yes, which is one reason they are prescribed. They are a different class to penicillin, but always tell your prescriber about all your allergies.
Why are these antibiotics so prone to interactions?
Some macrolides affect the way the body breaks down other medicines, which can raise the levels and side effects of those drugs. A full medicines check helps avoid problems.
Do I need to finish the whole course?
Yes. Completing the prescribed course gives the best chance of fully clearing the infection and helps reduce antibiotic resistance.
Will it help my cold or flu?
No. Macrolides treat bacterial infections, not viruses, so they do not help with colds, flu or most sore throats.
What if I feel sick while taking it?
Nausea and stomach upset are common. Taking it with food where allowed can help, but contact your prescriber if it is severe or you cannot keep doses down.
Authoritative sources
Always verify against the source
This overview is for orientation. For doses, interactions, contra-indications and the full monograph, use:
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