Leflunomide has an extremely long half-life so it is understandable that the rash persisted for 6 weeks. I think the half-life of leflunomide is several weeks as compared to a few hours for many medications.

The elimination half-life of prednisone is three to four hours, during which time your body reduces plasma levels of the drug by half.

I have mixed feelings about leflunomide. I was doing well on luflunomide for about a year in terms of decreasing my prednisone dose. During the year I developed 3 infections which required antibiotics. My rheumatologist stopped leflunomide due to infections even though it was probably working for PMR.

My rheumatologist didn't say leflunomide was what caused the infections. She said prednisone shared some of the blame because the combination of prednisone and leflunomide was suppressing my immune system too much.

The problem with prednisone is not about its half life. Prednisone suppresses adrenal function which prevents it from being stopped quickly when side effects occur.

The ideal medication for PMR/GCA would have a short half-life and doesn't suppress adrenal function. Also a medication that doesn't have too many side effects is important. I'm not sure a perfect medication exists.