Hi d.biagini, The fever blister which you have after taking the drug meloxicam was most likley not due to the drug. This drug is an NSAID, which is commonly given for the pain condition and this can also reduce the fever if it is there in the patient. Most of the time the fever with blisters is viral infection and most common cause for this is decrease in the immune status of the person. Since you are haing a back pain and stress associated with this condition cmay have decrease the immune condition and may have cause the viral infection which is presenting as fever with blisters. As far the contagiousness is considered, it depends on the type of viral infection and also on the immune satus of people who is exposed to this. Most of the viral infection are contagious in nature and I would advice you to prevent the exposure to others as much as possible till the blister are dry. Thanks and take care.