Which is more hygienic?
If you are suffering from a cold or the flu, then yes, tissues are a better option. The reason for this is you are essentially blowing nasal secretions containing the virus - that is causing your illness - into the tissue. As long as you throw that tissue into the bin (without re-using) and wash your hands, tissues are the most hygienic option.
Are handkerchief's sanitary?
By using a handkerchief, you are increasing the chance of spreading the virus (not to yourself, as you already have it – but to those around you). Saliva doesn’t contain as much of the virus as nasal secretion, so by blowing your nose several times into a hanky, which is potentially already feeling a little ‘damp’, and then not washing you hands straight afterwards, you are increasing the spread of virus when touching other items such as door knobs and computer keyboards with your ‘hanky hands’.
Is a hanky or tissues better for hay fever?
If you prefer to use a hanky for hay fever, then go right ahead, as your nasal secretions aren’t riddled with a virus. However, it is still advisable to change your hanky on a regular basis if your nose is constantly running. Otherwise, give some natural remedies a go and you might be able to say goodbye to the hanky for good.