Any drug that changes the way in which body chemistry works can cause harm. Even the humble aspirin becomes poisonous if you take too many tablets. Indeed, the degree of danger decides whether a prescription is needed to get the drug. The more dangerous it can be, the more likely the FDA will designate it prescription-only. So, when you see a drug requiring a prescription, you should assume there's a real risk of side effects unless you use the drug with care. In the days before the internet, this system worked well. Everyone dutifully saw their regular physician and listened to an explanation of how to manage the risks. Today, we can bypass doctors and buy from an online pharmacy. This gives you the drugs without the oral warnings. Research shows few people actually read the literature that comes with the packaging.
In theory, corticosteroids should be less dangerous because they mimic the hormones your body produces naturally. Except, the volume of production is far higher than you could ever produce naturally. This disturbs your body's production of hormones. When it finds there's already too much, it stops production. Once this happens, you are completely dependent on continuing the drug. You cannot just stop taking it. You must slowly reduce the dosage to restart your body's own production.
When you take a tablet, this processes the drug through your stomach into the bloodstream and the whole body is affected. This means it's far more likely you will experience the side effects. Whenever possible, you should use a delivery system that targets the medical problem. So, for example, if you suffer from asthma, use an inhaler. This delivers the drug directly to the lung and limits the potential damage to the rest of your body. In fact, you may still have problems with inhalers but, if you regularly rinse your mouth out with water and gargle immediately after use, your mouth and throat should avoid damage. Staying with asthma, this is not to deny the use of Prednisone. But it suggests a different strategy to get the best results. For everyday use, an inhaler is best. If you have a serious attack, a short burst of Prednisone can quickly reduce inflammation of the airways and resolve the problem. This would suggest it's always better to discuss treatment with a doctor to reduce the risk of side effects.