Kobayashi Pharmaceutical confirmed Thursday two more deaths associated with its beni kōji red yeast rice dietary supplements. The company had already been linked to two prior deaths and over 90 hospitalizations in relation to the pills and kidney-related conditions, according to the health ministry, which held a hearing with the Osaka-based firm.

It is suspected that the health issues stem from a toxic, potentially mold-like substance in the products, but the company has yet to pinpoint a specific cause.

The health issues appear to be concentrated among those who ingested the supplements manufactured after September. Commonly reported symptoms include swelling, fatigue, and reduced kidney function.