Shelvey was sent off for violent conduct following a first-half clash with Forest's Henri Lansbury.
Dummett was later deemed to have denied a clear goalscoring opportunity.
The incidents resulted in penalties for Forest, both of which were saved by Newcastle goalkeeper Karl Darlow.
However, the league leaders went on to lose the match 2-1.
England midfielder Shelvey and Wales full-back Dummett will now be available for Saturday's home game against Birmingham City.
Newcastle pair Paul Dummett and Jonjo Shelvey have had suspensions withdrawn after winning appeals against their red cards in Friday's 2-1 Championship defeat at Nottingham Forest.