@besmith57 - Sorry your post got missed but there are a lot of other members who have asked questions and shared experience with leflunomide. Here is a link showing the discussions and comments by other members that you might find helpful - https://connect.mayoclinic.org/search/?search=leflunomide

You mentioned your doctor is suggesting Methotrexate. Have you discussed your concerns of the side effects with your doctor and the possible alternative?

Good morning @besmith57 - I'd like to tell you about my PMR-friend who just returned from visit with his Rheumatologist, and because of your post I did a bit of searching around re: PMR and MTX(methotrexate)
BUT first -
ON March 3rd you wrote :
"I was diagnosed with PMR a month ago after excruciating pain to the point I had to get my walker back out from my lumbar fusion. I will be weaning off from 20mg to 15mg on Wednesday. I know I have to get off prednisone because of my osteoporosis. "-- yesterday you said you were at 5mg and "pain returned"-- pain AND stiffness ? exactly like your initial onset ?
IMO- This seems pretty fast developments in only 3.5 months, particularly your tapering ! Have you had follow up blood work ? Did you ever have 100% relief from symptoms with your initial dose ( 20mg? - I did not and had my first flare-up - my rheumatologist increased to 30 mg and have tapered down to 3 mg /day in about 11 months) . There are many in this forum who might advise you to be "more patient".

May I ask where do you live ? someone reported that in Australia patients must try MTX before they are "approved " for biologicals. If you live in USA - did you get a prompt appointment with a Rheumatologist ?

Anyway my friend ( has been relapsing for last 3 yrs ) had a discussion about KEVZARA with the rheumatologist and he will just try again to increase Prednisone to 7 mg/day and taper again to 5mg/day - steroid sparing seems NOT to be the priority for him ! And the cost of KEVZARA was a sticker shock !

If VERY QUICK steroid sparing is a priority for you --In 2023* an international study stated : "In addition, high-quality evidence is lacking to support routine concomitant glucocorticoid sparing treatment with methotrexate, and given the limitations to use this drug in older adults with restricted renal function, new treatment options are needed for people with PMR. " so I agree with @johnbishop about further discussion with your doctor.......
If you'd like to get into a IL17 trial for PMR ( sponsored by Novartis) - maybe you can try that . It is recruiting still I believe ......https://www.novartis.com/clinicaltrials/study/NCT05767034

*I will attach my notes about MTX . You'll be pain free I bet someday soon : )