My uncle has been taking disulfiram for abstinence of alcohol with proper counselling. if a disulfiram reaction occurs, how will he overcome it and what are the reactions?

The reaction would stop when the ethanol he drank has cleared his system. The time for 1/2 of ethanol to leave the body is 2-3 hours and by 8-12 hours it would be gone. He will have to accept & deal with the nausea that is part of the reaction until it fade, concentrating on staying hydrated. Simple fat free meals trigger less problems while the reaction fades.