I am taking alendronic acid, 1 weekly. Need root canal treatment for gum boil. Should I stop taking this? If so for how long before & after treatment?

Fosamax (alendronate) Has been shown to pose a potential of bisphosphonate related osteonecrosis of the jaw (bronj) primarily with invasive oral surgery procedure and extractions. Eliminating an infection via rct of a tooth and avoiding an extraction is exactly what you should be doing. More info for the public on bronj is available here: http://www.Aaoms.Org/bronj.Php.
No. Alendronic acid (fosamax) has been prescribed by your physician and should be taken as directed. Bisphosphonate drugs are known to have are side effects that could contribute to non-healing wounds in the mouth after surgical procedures. Root canal therapy is traditionally non-surgical and should not prevent you from continuing your prescription routine.