- hypoxia (sao2 <95%) - unable to take oral medication - unable to use inhaler - pregnancy or breast feeding - immunocompromising conditions - moderate/severe renal dysfunction : creatinine clearance (ccl) < 30 ml/min - moderate/severe liver dysfunction: ast or alt > 5 times upper normal limit - asthma or chronic obstructive lung disease

- hypoxia (sao2 <95%) - unable to take oral medication - unable to use inhaler - pregnancy or breast feeding - immunocompromising conditions - moderate/severe renal dysfunction : creatinine clearance (ccl) < 30 ml/min - moderate/severe liver dysfunction: ast or alt > 5 times upper normal limit - asthma or chronic obstructive lung disease