Prednisolone? Side effects? Sudden hearing loss?

Hi. I was given cortisone tablets for sudden hearing loss, which are supposed to help somehow. They're a relatively high dosage. I've now been given "Predni Tablets 20 mg" with the active ingredient prednisolone. I'm supposed to take 5 tablets at once on the first day and then taper off.

The side effects list "weight gain." I'm not going to gain weight just by taking these pills for 4-5 days, am I? I think that side effect only applies if you take them long-term or something, or am I misunderstanding?