Yes, it is a natural ingredient and almost has no side effects. Its safety has been approved by the U.S. Food and Drug Administration (FDA) and European Food Safety Authority (EFSA), as well as the Joint FAO/WHO Expert Committee on Food Additives (JECFA).

FDA

Konjac flour when used as a food additive is considered GRAS (generally recognized as safe) by the FDA (4).

EFSA
Konjac gum (E 425 i) and konjac glucomannan (E 425 ii) are listed in Commission Regulation (EU) No 231/2012 as an authorised food additive and categorized in “ additives other than colours and sweeteners” (5). Their applications are listed in “Group I” with the maximum level “10 g/kg”. (6)

Safety re-evaluation in 2017
After the studies of carcinogenicity, genotoxicity and other researches, EFSA concluded that there was no need for a numerical acceptable daily intake (ADI) for the uses of konjac gum (E 425 i) and konjac glucomannan (E 425 ii) as food additives and no safety concern under the use of 10 g/kg. (7)

JECFA
Both konjac gum and konjac glucomannan are categorized as konjac flour by JECFA that functions as an emulsifier, gelling agent, stabilizer, thickener. (8)

Acceptable daily intake: ADI “not specific” set in 1996. (9)

http://www.chinafooding.com/Konjac_Gum