What can I do to heal my hand, foot, and mouth disease blisters that have persisted over 20 days?

Hi,

It is unusual that the blisters have persisted more than 20 days if you have HFM disease. HFM disease will usually last about 1 week or so and clear on its own with or without active treatment.

I suggest that you see your doctor or a dermatologist for a full assessment to exclude other conditions such as autoimmune disorders which may present in a similar manner.

Hope this helps!