Side effects of prednisolone for asthma?

Several. Prednisolone is usually given to patients with an acute asthma exacerbation that is not improving with bronchodilators and inhaled steroids alone. The general course is 3 - 7 days. Over that period of time one can expect possible side effects to include: emotional lability, increased appetite, weight gain (mainly from water retention), aggressive behavior. Not everyone experiences any or all these.
Lots. Prednisolone is a steroid used to shut down inflammation that causes asthma symptoms, trouble breathing, etc. Used infrequently in short bursts, it can cause mild behavioral changes, agitation, and hyperactivity. Over time, with repeated use, it can cause a decrease in growth, fat deposition, acne, and bone thinning.