Summer is ending and that means we can look forward to the flu season. But reaching for the Tylenol is no longer a sure thing, since the venerable pain reliever remains largely out of stock. This is due, of course, to ongoing manufacturing difficulties that Johnson & Johnson has had for nearly two years thanks to bottles that smelled musty, contained too much active ingredients or metallic specks, among other things (see here, here and here).

Of course, there are alternatives, such as lower-cost store brands that have been available for months. “Generics may use a different type of salt or sugar to compose it, but it has the same active ingredient, which is acetaminophen,” Kristen Binaso, senior director of corporate alliances for the American Pharmacists Association and a pharmacist in Clifton, New Jersey, tells The Wall Street Journal.

For J&J, though, this amounts to stiff competition that may be hard to derail once its production problems are fixed, a step that sources say may not occur until the end of 2012 or so. The healthcare giant is operating under a consent decree and completing retooling a Pennsylvania plant. Knocking rival brands off store shelves is likely to prove challenging and eat into profits that J&J may have once counted on as the provider of dominant over-the-counter brands.

The problem has gotten so bad that J&J has taken to offering a ‘product locator’ on the Tylenol.com web site to help consumers find a store that may actually sell one of the many versions of Tylenol (look here to see if you can find any yourself). Tellingly, the drawing of the basket on the web site is empty. Perhaps if J&J were more confident of replenishing shelves, the basket might contain a few Tylenol bottles.