At a glance
- “Broad” refers to range, not strength.
- The appropriate choice depends on the infection and the person.
- Focused treatment may be possible when the likely bacterium is known.
- Unnecessary antibiotic use adds side-effect and resistance risks.
Why might a clinician use one?
Sometimes the cause of a serious infection is not yet known, or more than one group of bacteria may be involved. A clinician considers available evidence, local resistance patterns and the urgency of treatment.
When a cause is clearer, the treatment may be reviewed. Any change should be made by the treating team, not by the patient using a web chart.
A simple comparison
| Feature | Broad spectrum | Narrow spectrum |
|---|---|---|
| Target | More types of bacteria | A smaller set of bacteria |
| Potential role | May be considered when the cause is uncertain | May be preferred when a suitable focused option is available |
| Selection | Requires clinical judgement | Requires clinical judgement |
These descriptions are general. They do not indicate which antibiotic is suitable for you.
The trade-off
An antibiotic’s activity extends beyond the bacterium causing an infection. Unnecessary or overly broad use can disturb other bacteria in the body and may encourage resistance. Like all medicines, it can also have side effects.
That is why “broad spectrum” should never be treated as a synonym for “the best”.
What to ask your prescriber
You can ask why a medicine was chosen, what improvement to expect and what to do if you feel worse. Follow the directions provided for your own course.
Sources
Original referencesThese sources informed this overview. Their organisations do not endorse or review this website.
This page is for general education only. It does not replace advice from a doctor, pharmacist or other qualified healthcare professional. Read our medical disclaimer.