Prilosec OTC, the country's bestselling over-the-counter heartburn medication, has been in short supply for more than three months, pharmacists and consumers report. Both large chain stores and independent pharmacies say they are receiving less of the medication than before. And when the product reaches the shelves, it quickly sells out.

Why Distributor Procter & Gamble underestimated demand for the acid reflux drug, which hit the over-the-counter market in September 2003, said company spokesman Kurt Weingand. "America's stomachs are in much worse shape than we'd ever predicted," he said.

Help Is on the Way Weingand said supplies should start increasing in December and January. In the meantime, he suggested calling around to find out which local stores have it in stock. CVS has increased its inventory of other OTC heartburn medications, such as Pepcid AC and Zantac, said Mike DeAngelis, a spokesman for the chain.

Strong Stuff Prilosec OTC and prescription-only Nexium, both made by AstraZeneca, are proton pump inhibitors, the strongest kind of heartburn medication. The once-a-day pills deactivate the acid pumps in the stomach for up to 24 hours and are considered safe for long-term use -- although users of the over-the-counter medication are advised to see a doctor if they need it longer than two weeks. Prilosec OTC is the only proton pump inhibitor available without a prescription.

Telling Facts There's no shortage of Nexium, which is far more expensive than its OTC sister drug. A 30-day supply of Prilosec OTC retails for less than $30; the same dose of Nexium (which many doctors describe as virtually identical to Prilosec OTC) runs $140 to $150.

Last month, the AFL-CIO and two California senior citizens groups filed a class action lawsuit against AstraZeneca, alleging the company used false advertising and deceptive practices to persuade doctors and patients to switch from Prilosec to Nexium before the patent for Prilosec expired in 2001. AstraZeneca spokesman David Albaugh said the company rejects the claims and will vigorously defend itself.

-- Lisa Barrett Mann