I don't know if there is offical advice, but my friend who lives in Goa puts a sachet of diarohea salts in a litre bottle of water and sips that all day. No idea if that's healthy or not though. Doctors would probably just say to eat regularly and get your salts from there. I asked my Australian friend what they do, and after she finished laughing at us for getting in a tizz about 32 degrees, she said they don't do anything about salt, they just sit indoors and complain. :D