This is called
gynecomastia.
Prednisolone is not known to cause gynecomastia. There are many drugs known to cause breast enlargement in male, but prednisolone is not mentioned. Prednisolone is a steroid.
Steroids are of corticosteroid and
anabolic steroid. Prednisolone is a corticosteroid. Anabolic steroid can cause breast enlargement in male. Prednisolone is not an anabolic steroid. Gynecomastia is not physically harmful, but in some cases it may be an indicator of other more serious underlying conditions like liver disease,
kidney failure, obesity, tumors and Klinefelter’s syndrome. But the most common cause in adolescence is physiological that resolve spontaneously with increasing age. Drugs are available to treat resistant gynecomastia but it needs to be taken under proper supervision. Surgery is also done in some cases.
Advice
1. Wait and watch until age 18 years. If it does decrease in size after 18 years, contact your doctor and get investigated the cause. You can also contact your doctor now also if your son is too much anxious about his breast.
2. Continue anti – asthma drugs as suggested by your doctor
3. If your son is obese then suggest him to lose weight by lifestyle changes and changing food habits
Good luck!!