There's no exact way to tell because everyone is different.
You're not supposed to break PrilosecOTC pills because they have an enteric coating that helps them dissolve more slowly in your digestive system, so that's not a good option.
When you're ready to try weaning yourself off PrilosecOTC you should pay close attention to your diet - avoid alcohol, caffeine, chocolate, tomato-based fooRAB and anything else that causes your acid to flare up as much as possible for a while.
I'm assuming you're only taking one PrilosecOTC a day, so the night before you skip your first PrilosecOTC take a Zantac 150 (generic version contains 150 mg of ranitidine) or Maximum Strength Pepcid (20 mg famotidine) at bedtime.
In the morning, take another 150 mg Zantac or 20 mg Pepcid in place of PrilosecOTC, and use Tums or another mild antacid through the day if you need to. Continue taking the maximum strength Zantac or Pepcid twice a day for a couple of weeks.
Assuming your still managing at that point, step down from the maximum strength Zantac or Pepcid to the normal strength (75 mg Zantac or 10 mg Pepcid) twice a day for a couple of weeks, and use Tums to manage any minor flare ups.
From twice a day, you should be able to drop down to once a day with the Zantac or Pepcid (depending on the type of reflux you have you'll have to experiment with the best time to take it - morning or evening), and then after a couple of weeks try stopping it altogether and using Tums to manage any flare ups you have.
You'll probably have to experiment to see whether Zantac or Pepcid works better for you, and try to identify any food or drinks that cause flare ups and avoid them, and throughout this process you may need an occasional PrilosecOTC to calm things down if you get a big flare up.
