Hello @novabill, Welcome to Connect. My PMR is currently in remission. I don't have any experience using Melatonin with prednisone but hopefully other members may be able to share some feedback or suggestions for you. I did a search on several drug interaction websites and did not find any information on melatonin and prednisone have an interaction but I did find some information supporting what you may be experiencing. Both occurrences of PMR I was started on 20 mg prednisone and it made me pain free and I was eventually able to taper off.

"Steroids and immunosuppressant medications -- Melatonin may cause these medication to lose their effectiveness. DO NOT take melatonin with corticosteroids or other medications used to suppress the immune system." -- Melatonin: https://www.mountsinai.org/health-library/supplement/melatonin

Have you asked your rheumatologist or pharmacist about a possible interaction between the Melatonin and prednisone's effectiveness?