Updated Speculation about disappearing tampons started surfacing last September.

On the “Write the Company” blog, many women said they were upset – “outraged” even — that they were no longer able to find their favorite, ultra-absorbent o.b. tampons in drugstores.

The brand, o.b., is made by McNeil-PPC, a unit of Johnson & Johnson, and has a loyal customer base because many women find that the tampons fit better than similar products. They’re also smaller and more convenient to carry in a purse or pocket than some competing ones. In addition, unlike most other tampons, they don’t contain a plastic or cardboard applicator tube so they’re considered to be more environmentally friendly than other kinds of feminine hygiene products.

In November, it seems, the disappearances became more widespread, as consumers began reporting empty drugstore shelves of all kinds of o.b. tampons, not just the ultra line.

“Where have all the o.b.’s gone?” Carey Goldberg, a host at the Boston public radio station WBUR, wrote on the station’s health blog on Monday. “It’s decidedly odd.”

Decades ago, some types of super-absorbent tampons were linked to toxic shock. But little mention of illness has emerged this time around.

Bonnie Jacobs, a spokeswoman for McNeil, said that the company had discontinued the ultra line but that other o.b. products should be available soon.

“o.b. tampons experienced a temporary supply interruption that has resulted in some stores being out of stock,” Ms. Jacobs wrote in an e-mail message. “We are working hard to bring supply back in line with demand and expect these stores to be restocked soon. We apologize to o.b. customers who may have been inconvenienced.”

Ms. Jacobs did not elaborate on what caused the “temporary supply interruption.”

Because Johnson and Johnson products have been hit with a wave of recalls, largely because of manufacturing problems, in the last year, I sent her a series of follow-up questions:

“1) At which plant are the o.b. products made? 2) What was the cause of the temporary supply interruption? 3) Is the o.b. issue connected to the companywide manufacturing and quality improvement plan at McNeil?”

Ms. Jacobs replied in another e-mail: “I don’t have anything further at this time.”

McNeil did not immediately reply to a follow-up query asking whether the company had received reports from consumers of possible health problems like toxic shock syndrome, a rare bacterial infection that has been associated with the prolonged use of extra-absorbent tampons and that can cause fever, internal organ damage and even death.

In the late 1970s, toxic shock syndrome became a public health concern in the United States after the introduction of super-absorbent tampons, particularly the Rely brand from Procter & Gamble; in 1980, after P.&G. recalled the products, the incidence of tampon-associated toxic shock syndrome declined.

The Food and Drug Administration has regulated tampons as medical devices since that time.

A search of the F.D.A.’s adverse event database for medical devices turned up a handful of consumer reports of problems with o.b. tampons over the last five years. Such health complaints are not necessarily caused by the products cited in the reports.

The reports in the F.D.A. database about o.b. tampons included complaints of headache, fever, nausea and abdominal pain as well as infections caused by tampon remnants remaining in the body.

One complaint from last year concerned a consumer who said she had been using o.b. tampons for two years.

“Consumer saw her physician and was prescribed medication for a vaginal infection. After one day of treatment, a ‘ball of tampon threads was released from the uterus,’ ” the report said. “The consumer reported that the physician suspected that the ball consisted of ‘little pieces of tampon from over a period of time.’ ”

A spokeswoman for the F.D.A. said the agency was “not aware of any quality control or manufacturing issues with o.b. tampons.”