Hi Sandy

Well my first suggestion is to call your doctor or pharmacist with these questions.  I don't think you should up your meds unless this is what your doctor advises you to do. 

On this drug site they say this about Prestiq: 

"It may take several weeks or more for your symptoms to improve. For best results, keep using the medication as directed."

Any medication to help with mood is going to take some weeks to really kick in.  Be patient...wait to feel the full effect of your medication.  If you up the dose you may experience more severe side effects.  You don't want to mess with the dosage unless you get the okay from your doctor.

On this "Ask the Pharmacist" site I found some information for you about taking the antacids and Prestiq: 

"Pristiq (Rx, oral): A new anti-depressant and hot flash remedy, it is derived from it's parent drug Effexor which has been available for years. When Effexor (venlafaxine) undergoes a chemical reaction in your body, it's child is born, Pristiq (des-venlafaxine). Is Pristiq better? Only if you have inadequate amounts of healthy flora (probiotics) or you take acid blockers/antacids routinely."

Again my best suggestion is to call your doctor or pharmacist and ask about the antacids and also about when this drug may begin to help you.

Thank you for your question.