For suppression of both viral and bacterial respiratory infections, we present candidate formulations and treatment protocols based on nano-silver colloids (NAgC) by inhalation delivery. Special evaluation is given to Corona virus. We are not aware of any published theoretical or clinical research on medicinal inhalation of silver particles. In this article we lay the grounds for such clinical evaluations to be done. The formulations are based on the available experimental data. Yet, according to our analysis, the published experiments were all done on sub-optimal NAgC. Hence, following the presented framework, future tests with our recommended more optimized NAgC should lead to improved formulations. We analyse three core aspects: (a) material composition options, (b) associated effective treatment dosages, and (c) the delivery method. Building towards potential clinical evaluation, we discuss the evidence for the safety of the proposed treatment based on published tests and guidelines in the EU and USA for inhalation of silver nanoparticles. From the clinical therapeutic point of view, we argue that our treatment formulations may be most effectively applied as a first-line intervention at an early stage of respiratory infections, i.e., when mostly affecting the upper respiratory system and bronchial tree. The proposed treatment is a measure with the potential to suppress proliferation of the viral infection across the respiratory system, thereby giving more time for proper immune system response and lowering the risk for aggravation and spread of the infection. For example, the proposed formulations could be used to control local outbreaks of COVID-19 via early stage home treatment. In the context of bacterial pneumonia, we note that similar NAgC dosages should also provide anti-bacterial effectiveness. We propose that for hospital ventilator associated pneumonia (VAP), inhalation delivery of NAgC can be implemented prophylactically to lower VAP risk. For completeness, we discuss manufacturing and commercial availability for near term wide public usage.