Harvard Health Letter

Do PPIs have long-term side effects?

Nexium and the other proton-pump inhibitors are great at reducing stomach acid, but that might have some unintended consequences.

 Madison Avenue has given stomach acid a bad name, but it's really kind of a bum rap. Dip into any physiology textbook, and you'll find that stomach acid serves several constructive purposes. Pepsin, an enzyme that is essential to the preliminary digestion of protein, needs an acidic environment in the stomach to be effective. The strongly acidic hydrochloric acid pumped out by cells in the lining of the stomach also plays a direct role in the early digestion of some foods. And stomach acidity is a built-in barrier to infection: many bacteria and other pathogenic fellow travelers don't make it out of the stomach alive because of the low pH levels they encounter there.

Long-term use

Yet millions of us spend billions of dollars each year on products and medications designed to lessen or get rid of stomach acid. The old standbys, antacids like Maalox and Mylanta, have been supplanted in many cases by drugs that go to the source, acting on the cells that produce the hydrochloric acid, rather than just neutralizing the acid. Starting in the late 1970s, histamine2-receptor (H2) blockers like cimetidine (Tagamet), famotidine (Pepcid), and ranitidine (Zantac) came on the market. They were followed by the proton-pump inhibitors, or PPIs, which include esomeprazole (Nexium), lansoprazole (Prevacid), and omeprazole (Prilosec). The PPIs are increasingly the acid reducers of choice because they're far more effective than the H2 blockers. They're also quite a bit more expensive; for example, the over-the-counter version of Prilosec is about twice as expensive as the over-the-counter versions of Pepcid and Zantac.

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