What criteria should I use to determine when to prescribe antibiotics for respiratory tract infections in adults?

Guideline-aligned answer with reasoning, red flags and references. Clinically reviewed by Dr Kola Tytler MBBS CertHE MBA MRCGP.

Posted: 22 August 2025 Guideline-Aligned (High Confidence) Clinically Reviewed
Dr Kola Tytler MBBS CertHE MBA MRCGPClinical Lead • iatroX

Antibiotics for respiratory tract infections (RTIs) in adults should be prescribed based on a thorough clinical assessment considering the severity of symptoms, risk factors, and diagnostic support tools.

  • Do not routinely prescribe antibiotics for acute respiratory infections (ARIs) unless there is clear clinical indication. Most ARIs are self-limiting and do not require immediate antibiotics .
  • Use clinical judgement and consider the patient's overall health, comorbidities, and social circumstances. The threshold for prescribing antibiotics is lower in people with comorbidities, multimorbidity, or frailty .
  • For lower respiratory tract infections (LRTIs) where the need for antibiotics is unclear, consider a point-of-care C-reactive protein (CRP) test: offer immediate antibiotics if CRP >100 mg/L; consider a back-up (delayed) prescription if CRP is between 20 and 100 mg/L; do not routinely offer antibiotics if CRP <20 mg/L .
  • If pneumonia is clinically suspected, use the CRB65 score to assess severity and guide management: consider hospital assessment for CRB65 ≥2; shared decision-making for CRB65 =1; home care for CRB65 =0 .
  • Do not rely on rapid point-of-care microbiological or influenza tests to decide on antibiotic prescribing. These tests are not recommended for guiding antimicrobial use in ARIs .
  • When antibiotics are considered, discuss with the patient the likely nature of the illness, benefits and harms of antibiotics, alternative options, and safety-netting advice. Document the reason for prescribing or not prescribing antibiotics and the care plan .
  • Do not issue immediate antibiotic prescriptions for likely self-limiting infections; consider back-up prescriptions or self-care advice instead.

Educational content only. Always verify information and use clinical judgement.