Glenavon were denied three valuable points when Johnny Taylor headed a stoppage-time equaliser for Ballymena.
United had taken the lead in the 47th minute when former Glenavon front man James Costello fired past keeper Andy Coleman from 15 yards.
Brian McCaul equalised on 70 minutes after Taylor had failed to cut out the through ball by Gary Hamilton.
Andy Mitchell headed Glenavon ahead after a goalmouth scramble but Taylor rescued United in the 92nd minute.
So Glenavon had to settle for a point and they are still scrambling to get clear from the one-from-bottom relegation play-off spot.
Lisburn Distillery are currently in that 11th place but Gary Hamilton's side are just one point better off and need to win at home to Dungannon Swifts next week to be sure of top flight survival.