Which to choose?
Amoxicillin: first line in community bacterial infection in non-allergic patients. Azithromycin: alternative in beta-lactam allergy or suspected atypical pneumonia (Mycoplasma). Important: indiscriminate azithromycin use drives serious resistance. Always confirm the indication with the prescriber.
Point-by-point comparison
Brands: Amoxil · Co-amoxiclav (Augmentin)
Brands: Zithromax
| Amoxicillin | Azithromycin | |
|---|---|---|
| Mechanism | Inhibits bacterial cell wall synthesis — bactericidal. | Inhibits bacterial protein synthesis (50S subunit) — mainly bacteriostatic. |
| Indications | Otitis media, streptococcal tonsillitis, sinusitis, UTI, pneumonia (in combination). | Tonsillitis in beta-lactam allergy, atypical pneumonia, respiratory infection in allergic patients. |
| Adult dose | 500-1000 mg every 8 h. | 500 mg/day for 3 days, or 500 mg on day 1 then 250 mg on days 2-5. |
| Onset of effect | Clinical improvement at 48-72 h. | Improvement at 48-72 h. |
| Duration of effect | Usual course 5-7 days. | Short course (3-5 days) with a residual effect. |
| Pregnancy | First choice. | Compatible when needed. |
| Breastfeeding | Compatible. | Compatible (watch for diarrhoea or thrush in the infant). |
| Paediatric use | From birth. 80-90 mg/kg/day in severe infection. | From 6 months. |
| Advantages | Narrow to medium spectrum, first line in community infection. Low risk of inducing resistance. Compatible with pregnancy. | Short course (3 days), high adherence. Useful in penicillin allergy. |
| Disadvantages | Allergic reactions (anaphylaxis rare). Clostridioides difficile diarrhoea. Ineffective against beta-lactamase producers. | Cardiac risk (QT prolongation, arrhythmia). High resistance rates in S. pneumoniae. NOT first line. |
Source: BNF, NICE antimicrobial prescribing guidelines, SEFAC
Frequently asked questions
Which is better, amoxicillin or azithromycin?
Amoxicillin: first line in community bacterial infection in non-allergic patients. Azithromycin: alternative in beta-lactam allergy or suspected atypical pneumonia (Mycoplasma). Important: indiscriminate azithromycin use drives serious resistance. Always confirm the indication with the prescriber.
Can amoxicillin or azithromycin be taken in pregnancy?
Amoxicillin: First choice. Azithromycin: Compatible when needed. Always ask a doctor or pharmacist before taking a medicine in pregnancy.
And while breastfeeding?
Amoxicillin: Compatible. Azithromycin: Compatible (watch for diarrhoea or thrush in the infant).