Prednisone and methylprednisolone are both corticosteroid (steroid) medications. They have similar effects on the body. The most powerful positive effect is reducing inflammation. Examples of conditions that can be treated include certain types of arthritis, colitis (bowel inflammation), and asthma and allergic reactions. Certain infections can improve more quickly when steroids are added to antibiotics. Corticosteroids are also used during cancer treatment. And they can help prevent the rejection of transplanted organs and reduce brain swelling after a head injury.

There's a long list of side effects associated with corticosteroids, including:

• Diabetes
• High blood pressure
• Weight gain and facial fullness
• Fluid and salt retention
• Impaired immune function
• Cataracts
• Muscle weakness
• Impaired wound healing
• Bone damage (called avascular necrosis)
• Thin, fragile skin with easy bruising
• Insomnia
• Acne
• Heartburn and stomach irritation

Prednisone and methylprednisolone have minor differences in their effects on the body. Compared with prednisone, methylprednisolone has higher anti-inflammatory potency. (It takes more prednisone to have the same effect as a given dose of methylprednisolone.) Methylprednisolone tends to cause less salt retention, but on the downside it is more likely to raise blood sugars, even in people without diabetes.

Another difference is that prednisone is available only as an oral medicine while methylprednisolone can be given by pill or injection. This can be important for people who cannot take pills or who cannot absorb medications well due to digestive problems. In these situations, injectable methylprednisolone may be a better choice than prednisone. Also, it can be easier to give high doses of corticosteroids by injection than in pill form.

Despite these differences, prednisone and methylprednisolone are more alike than different. They tend to be used for the same conditions with similar side effects.