IT BEGAN with tingling and numbness in her feet. It came and went, so Lee Russo, a healthy 39-year-old, ignored the problem.

Then she found herself falling down. She got a cane, started wearing leg braces. Her condition continued to worsen.

"Sometimes I was so weak I couldn't get out of bed," said Russo, now 43, of Inwood, N.Y. "I suffered. For a long time."

Russo's affliction? She and hundreds of others nationwide say they were poisoned by their denture cream.

Numerous lawsuits filed against GlaxoSmithKline, maker of Poligrip, and Procter & Gamble, manufacturers of Fixodent, allege that the companies knew their products were dangerous and did not protect consumers.

The suits allege that adding zinc to the products had adverse - and in some cases devastating - health effects on some users. Zinc helps bond dentures to gums.

"People are poisoned for many years and doctors are scratching their heads, trying to figure out what the problem is," said lawyer Eric Chaffin, a partner with New York-based Chaffin Luhana LLP.

"And the most reprehensible part of this is the companies have known for years about the horrific injuries that occur from zinc overload, and they did nothing about it."

Chaffin is representing 15 plaintiffs suing GSK and P&G in a case before Common Pleas Judge Sandra Moss in Philadelphia. Among the complainants, Chaffin said, are a woman who is now classified as a quadriplegic and others whose hands have deteriorated and look like claws.

Tom Kline, a well-known plaintiffs' attorney with Philadelphia's Kline & Specter, represents Diann Jones, of Schuylkill County, in a separate suit against GSK.

"To meet Diann Jones is to understand the devastating, crippling, and forever life-altering consequences of what happens when a pharmaceutical company makes a product and doesn't warn users of its problems," he said.

Jones, 44, used Poligrip for eight years after losing her teeth due to pregnancy complications. Her neurological decline began after about five years. She now uses a walker and is housebound, unable to care for her 11-year-old son

"She's done nothing wrong but use Poligrip," Kline said. "She thought she was using the equivalent of toothpaste. She didn't know that every day she was being poisoned by a heavy metal."

Kline said the fact that GSK launched a voluntary recall of Poligrip EX in Japan last week "speaks volumes."

"We have a Philadelphia corporation with a product that is being questioned literally around the world," he said. "When you see it was recalled in Japan and not recalled here, a general red flag goes up."

A larger suit involving 75 plaintiffs is in federal court in Miami. In another Florida case, the family of Rodney Urbank, 63, has filed a wrongful death suit against GSK, claiming Poligrip contributed to his 2008 death.

On March 31, attorneys involved in the state suit are expected to come before Judge Moss to discuss discovery issues as the cases move to the deposition stage. The plaintiffs expect a trial as early as this fall.

Both GSK and P&G declined to comment on the suits. But both say their products are safe when used as directed.

That's one issue of contention in the suit: Plaintiffs allege that they were unclear about how much product was safe to use until it was too late and their bodies had been damaged.

Russo said she went through about a tube of Poligrip a week and kept a small tube of Fixodent in her purse when she went out. She went through about a tube a week, four tubes a month.

She used as much adhesive as she felt it took to keep her dentures comfortable, a little more on her bottom plate as it was somewhat ill-fitting.

Late last year, GSK began including an insert in its denture packaging, noting that even the smallest size tube - 0.75 oz. - is meant to last about three weeks.

Russo said she didn't know this. Even if she did, by the time it was released, her body was already damaged. Russo says GSK's contention that she and other users abused the product were unfair and a "cop-out."

"The whole point of denture cream was to put it on so dentures stayed in your mouth," Russo said. "Their 'too much' may not have been my 'too much.' Unless you came to my house and said, 'Use this much,' it's the only way I'd know your 'this much' and my 'this much' was the same."

Last month, GSK said it would no longer use zinc in its denture-adhesive products "due to the literature and increasing case reports we were seeing" involving problems with zinc intake, spokeswoman Malesia Dunn said.

But the company did not recall products that contained zinc. The zinc-free products should be available by April or May, but the others are still being sold since they are safe when used as directed.

"The concern comes from a very small number of people who are using the product in excess over the long term," Dunn said. "This isn't something you can go and take it home tonight and use it before bedtime and then there'd be a problem. It's long-term excessive use."

Andy Alonso, who is representing federal plaintiffs, said that although he was happy to see that GSK is removing zinc from its products, the company didn't act soon enough.

"It seems to me that we've been right all along and unfortuately, it's too late for a lot of people," said Alonso, of the New York firm Parker Waichman Alonso LLP. "It's gratifying, but it's too late."

Procter & Gamble has no plans to change Fixodent's formula, P&G spokesperson Tricia Gottlieb said in an e-mail.

"The amount of zinc a consumer would ingest from normal, as-directed, daily usage of Fixodent . . . is comparable to the zinc in six ounces of ground beef," Gottlieb wrote, also noting that "Fixodent's formula contains about half the amount of zinc used in Super Poligrip."

Zinc is needed for a healthy immune system and healthy skin. The recommended daily allowance of zinc is 11 mg for an adult male and 8 mg for an adult female, according to the Institute of Medicine of the National Academies. The maximum amount of zinc that can tolerated daily is 40 mg.

Another side effect of excess zinc in the body is the way zinc blocks the absorbtion of copper. Copper helps form red blood cells, bones and collagen. A lack of it can create anemia and nervous-system problems.

Neurologists have been aware of zinc's negative effects since 2008. After seeing four patients at her medical clinic suffering from anemia and neuropathy symptoms like tingling and numbness in 2007, Sharon Nations, a nerve and muscle specialist at the University of Texas Southwestern, decided to investigate.

She found that all four patients used a large amount of denture adhesive - about two tubes a week - and were being exposed to about 330 mg of zinc each day. She published her findings in Neurology magazine in August 2008.

After the study was published, Nations performed tests on about a dozen people who used denture adhesive in the recommended manner. She found they had normal zinc and copper levels.

"Taking large amounts of zinc, like in a 50 mg supplement like people do when they have a cold, may be fine for a few days," Nations said, "but if you take it over a long period of time, say a year, you have to be careful not to take too much."

Nations advised her patients to start taking copper supplements and to stop using denture creams with zinc. Their zinc and copper levels returned to normal, she said, but most of their neurological problems remained.

"It's hard to have significant improvement," Nations said. "Our patients improved to a small degree but still had deficits."

Russo also addressed the imbalance in her body with copper supplements. Her blood returned to normal.

"I was a little shocked, actually. It just seemed like it was something so simple," Russo said. "At one point, I was so weak I couldn't get out of bed and the cure was to go to the vitamin store and buy a bunch of copper pills."

But "cure" is an overstatement. Russo's mobility problems remain. She used to wear high heels, dashing about to keep up with her husband and two kids. Now she pushes her numb feet into sneakers and stays home.

She was, she said, "happy-go-lucky." Now she's angry. In a choked voice, she described why:

"Everything has changed for me. I can't work. I can't take care of myself. My children hurt. My husband hurts. I hurt. . . . I don't want this to happen to other people or have their families go through this."