Is there any reason not to make a permanent version of that? Here's what Street Magic has to say about what spells can be made permanent.
QUOTE
Permanent spells must be maintained for a time, then they become permanent. Only spells that restore the target to its original, natural, unaltered state should be permanent in duration. Spells that heal or repair damage, disease, the effects of drugs, poisons, and so on, for example, are all good candidates. If the spell provides some sort of game bonus (other than restorative), the effect should not be permanent. The gamemaster has the final say on whether it is possible to create a permanent version of a spell.
Restoring you to your original state? Check, as long as you weren't allergic to sunlight pre-HMHVV.
Repairs the effect of disease? Check.
Does not provide any sort of game bonus (other than restorative)? Check.
So why not sustain it for a minute or two and have done with it?