The Naltrexone at low dose of 4.5 mg is metabolized very fast through your system. It actually is only in there for about 3 hours, but you have the benefits of it for the next 18-20 hours. You take it at bedtime and let it do it's work while you are sleeping. Some people have reported sleep disturbances (short duration, resolving and not returning) but I didn't have any side effects from it at all.
The side effects I have had from methotrexate and remicade were fatigue (one thing it is supposed to help!) and a chemical smell in my skin. Overall that mixture just did not do a lot for my symptoms...I had a lot of inflammation and joint pain, plus the fatigue, even while on those drugs. Plus the Remicade is soooo expensive...I was getting it every 6 weeks, and my insurance was paying $2700 every time!! Outrageous.
One wonderful thing about the Low Dose Naltrexone...in my town it costs only $10.76 for a whole month of capsules...$5 I pay after my insurance. It has to be compounded down to 4.5 mg from 50 mg tabs, which is the lowest dose it is manufactured.