Can a lupus patient get another autoimmune disease?  

Has higher chance. A person with one autoimmune disease, such as lupus, has a higher chance of getting another autoimmune disorder, such as thyroiditis, type 1 diabetes, rheumatoid arthritis, grave's disease, vitiligo, etc... However, having an increased risk of getting a disorder doesn't mean the person will surely get it. He might be only a little unlucky and have just one disease.

Related Questions

Could diets such as Paleo, dr. Fuhrmans, antihistamine diet etc. Reverse autoimmune diseases like Sjogrens and Lupus?

No. Modification of the immune system doesn't occur with anything like a normal diet. Perhaps with life-threatening starvation the immune system would be made dysfunctional (not recommended). And then, suppression is not at all like reversing. Read more...