I'm about to head into work, but I'll find the study that advocated using multiple B vitamins associated with the spectrum as they helped facilitate each others absorption and helped negate the possibility of malabsportion. It could just be my personal reaction to B12 that makes me feel an increase in body temperature or could be attributed to the way I structure my dosing. I usually do mega dosing of B12 with conjunction to my B5 mega dosing and my sub-lingual intake of B complex. I never go above 5000 mg/wk for b12 and even that is on the high end. My B5 consumption is subjective to how my skin is because it helps with acne, but usually 2000mg-4000mg/wk. The B Complex is just whatever it says on the packaging.
Be prepared to to pound back food after you get a solid couple weeks of consistent dosing.