My son has been on oral MTX for his CD for about
2 years now. Can't speak to the arthritis but he has had very few side effects from the MTX.
He takes 25 mg once a week and takes 1 mg folic acid the other 6 days. MTX strips folic acid from your body and folic acid is essential to a lot of body functions so it's important to get enough. If you have any absorption problems from the CD you might ask the doc or pharmacist about taking more than 5 mg and/or spreading it out over the week.
The things he has had trouble with - sun sensitivity, dehydration and fatigue.
He will get a bad sun burn through SPF 50 sunscreen the day after he takes the MTX. So please be very careful about sun exposure. I expect this is already an issue for you with the Lupus but wanted to make sure you knew that MTX is likely to make you even more sun sensitive.
Dehydration seems to be a much bigger issue since he went on the MTX too. He is much quicker to get badly dehydrated and feel sick from it. Easy to deal with if you remember to drink enough and have access to shade or a/c if the weather is warm.
Fatigue seems to be a bit worse on the MTX but who knows? That seems to be something CDers just have to deal with all the time.
Best wishes,
Patricia