A manufacturing problem at Tylenol parent Johnson & Johnson has left many area CVS stores without the popular pain reliever, although supplies are slowly returning to the Westford Valley Marketplace location.

During a check last week, the store had gotten new supplies of Children's Tylenol (in aisle 11) and has large supplies of its own brand of Acetaminophen.

A CVS spokesman told Reuters that CVS will try to have Tylenol in stores in each market, but will not be able to stock every store. 

Tylenol has battled manufacturing issues for years, and that's led to customers being more comfortable taking private-label versions of Acetaminophen, which is Tylenol's chemical name.

Also from the Reuters report:

In 2009, before the recalls started, Tylenol had 56 percent of the U.S. market share for acetaminophen, according to Euromonitor, a market research data firm. In 2012, that was down to 24 percent. At the same time, private-label market share has grown from 32 percent to 62 percent.