<blockquote>Quote<br><hr><i>Originally posted by: <b>Anonymous</b></i><br>is zantac an antiacid?<hr></blockquote>
Not exactly. An antacid simply neutralizes stomach acid, while meds like Zantac (which are actually acid/histamine-H2 blockers) prevent the body from releasing acid into the stomach in the first place.
The reason they say not to take antacid with antibiotics is because most antacids have magnesium in them. Magnesium is what makes the antibiotics ineffective.
Acid blockers like zantac and proton pump inhibitors like prevacid, nexium, and prilosec don't contain magnesium, so there is no problem taking them with antibiotics.