The deceased have been identified as Sachindra Reang (22), Adhiram Reang (40) and Bhabiram Reang (38).
On Monday, a total of 10 persons consumed the intoxicating acid which is used for rubber tapping.
The persons then fell ill and were admitted to public health centre. Later on Thursday, they were shifted to a hospital, where three persons were declared dead.
The incident happened in Kanchanchara in Dhalai district of Tripura.