Can pepcid 10 mg twice a day be taken for indefinite period of time. i am a chronic acid reflux suferer and must take some medicine to keep my symptoms under control?

10 mg, twice a day is probably not strong enough initially. I would recommend 20 mg twice a day for at least one month, when the symptom completely subsides, you can take 20 mg, daily as a maintenance dose. You need to practice antireflux measure which includes not lying down within 2 hours of a meal and raising the head of your bed for at least 2 brick blocks.