What are the side effects of konjac shirataki ?
konjac contains high glucomannan that would turn to dietary fiber ,
so for people who have stomach problems, it might cause digestive issues such as light bloating / diarrhea or loose stools /abdominal pain /gas /nausea.

What is konjac shirataki noodles?
Konjac has been known and used in Asia for over two thousand years. It is known as Moyu(yam) or Juruo in China, and Konnyaku in Japan.

from the perspective of nutriology, konjac is a food low in calories and high in dietary fiber. It is the dietary fiber that constitutes its effective nutritional component.

Are konjac noodles safe to eat?
Konjac noodle is is natural, alkaline foods, it is  is low calories, low carb, sugar free, fat free, gluten free, high fibre.Konjac's health-promoting functions are as follows:  
Slimming;
Improvement of sugar metabolism;
Regulation of lipid metabolism ;
Lower Cholesterol;
Balance blood sugar....

Konjac risks and preventive measures:
According to the FDA, some konjac jelly cause choking deaths in the elderly and children. It said that konjac gel is not dissolved in the mouth like other gelatin products. And the risks are higher if you have the following:
Taking konjac tablets
Taking konjac in any form without water
The old person
Have problems swallowing
(But konjac noodle has no such problems).

Konjac noodles would just have digestive issues, because it contains too much fiber. So if you have stomach trouble, please do not have high fiber foods,nor konjac shirataki noodles.

Summary shirataki noodles are safe to consume but may cause digestive issues for those who have stomach illness.