Weight gain is complicated and I would want proof that my child is truly producing too much acid and I would also want to try natural methods first before adding a drug. Consider also that Prevacid depletes the body of vitamin B12 and Pepcid, Tagemet and Zantac deplete the body of vitamin B12, Folic acid, vitamin D, calcium, iron and zinc.
These drugs may help in enzyme effectiveness but why are they not willing to work more closely with us to fine tune diets or use natural things like apple cider vinegar before meals before trying a drug. Traditional doctors are not going to tell you what those natural methods are because they don't know. It is worth doing some research and/or consulting with a holistic MD/dietician to see if some minor diet changes and/or supplements could help. You can purchase PH strips to test for acidity in the urine and try adding more alkaline foods to balance this if this is truly the issue. Baking soda in the bath helps as well. Many are easy changes and could be just the thing to aid in digestion.
Books on the topic and even a food chart:
<a target=_blank class=ftalternatingbarlinklarge href="http://www.amazon.com/s/ref=nb_ss_gw/104-8391610-8867953?initialSearch=1&url=search-alias%3Daps&field-keywords=acid+alkaline
">http://www.amazon.com/s/ref=nb...eywords=acid+alkaline
</a>