The 20-year-old from Northern Ireland finished the second day with four for 50 from 28 overs as Lancashire reached 193 for six in reply to Sussex’s 328, having been 137 for one.
Carson now has 15 wickets this season while 18-year-old debutant Jamie Atkins also had cause for celebration after removing Lancashire skipper Dane Vilas for a duck to claim his maiden first-class victim.
Lancashire openers Alex Davies and Keaton Jennings had put on 93 with few alarms with Jennings passing 50 for the first time this season, but Carson broke through in his fifth over when a quicker ball deceived Davies (34) who chopped on trying to cut after nearly three hours at the crease.
Jennings had been badly missed at slip by Stiaan van Zyl on 53 off the luckless George Garton but it wasn’t expensive. He added just seven more before edging Carson to slip off a delivery which turned just enough out of the rough.
That left Lancashire 137 for two, but they then lost four wickets for the addition of just seven runs. Stuart Meaker was rewarded for an excellent spell down the slope when Luke Wells (28), on his first return to the county where he spent ten seasons, followed one and was caught behind.
Carson’s third victim was Steven Croft (5), who was athletically caught off bat and pad by wicketkeeper Ben Brown diving forward, and it was 151 for five when Vilas was bowled off an inside edge trying to force Atkins through the off side.
Liam Livingstone’s first Championship innings of the season lasted just four balls as Aaron Thomason took a juggling catch at short leg to give the irrepressible Carson his fourth wicket and Lancashire had lost five for 24 runs in 8.5 overs. Josh Bohannon and Danny Lamb negotiated 23 overs to stumps but their side still trail by 135.
Earlier, Sussex added just six runs to their overnight 317 for seven before being dismissed for 323 with Lamb taking the last three wickets. He bowled Carson (13) via an inside edge, ran out Henry Crocombe (5) by deflecting the ball onto the stumps as Crocombe backed up before Garton (35) was last out, caught at fine leg. Lamb finished with three for 59 and Tom Bailey took three for 69 before Lancashire’s reply was held up by rain which forced a 40-minute delay.