The international, multi-billion-dollar black market for counterfeit pharmaceuticals is of growing concern to law enforcement because of the sometimes lethal consequences for patients taking medicine that doesn't perform as advertised.
"It's a serious problem, simply because of the potential for health issues, and the potential for deaths if it is not taken seriously," said Matthew Friedrich, the acting assistant attorney general for the Justice Department's criminal division.
He said organizations such as the World Health Organization "put the annual amount of counterfeit drugs sales at something like $35-40 billion per year. So there's no question that it's a large problem globally."
Pharmaceutical giant Pfizer estimates its annual losses to counterfeit drug sales at $2 billion. The company calls it flat-out fraud.
Pat Ford, Pfizer's senior director for global security, said the situation is "like the Wild West," which poses a particular problem for those dispensing the drugs.
"It gets to the point that pharmacists can't tell the difference. That's why we educate them" on features in the packaging that help distinguish the real from the fake.
And it's not just an international problem, but one unfolding right here in the United States.
Friedrich said U.S. regulatory and enforcement efforts help, "but it's certainly something that we need to stay on guard about."
Case in point: Jordanian national Iyad Dogmosh, who recently pleaded guilty to selling fake Viagra on the streets of New York. Law enforcement caught him with more than 38,000 pills in his possession.
Dogmosh may invite comparison to the classic snake oil salesman, selling to anyone willing to buy. But Friedrich said the counterfeit drug trade can be far more sinister.
"It is scary, but there's one difference: a snake oil salesman is selling snake oil. What Mr. Dogmosh was selling was a brand. He was selling a trusted brand, and he was taking advantage of the marketplace's trust for that specific label."
Dogmosh's counterfeit Viagra contained almost none of the pharmaceutical ingredients that make up the drug, though it looked just like the real thing.
Ford says counterfeit drugs can be virtually indistinguishable "between the shape of the product, the size of the product. Until we are able to put them side-by-side and do chemical testing, virtually you can't tell the difference between the two products."
Authorities say some consumers are playing Russian roulette when they pop pills. The reason: some consumers are not buying drugs at their local pharmacies, but on street corners and, increasingly, through online pharmacies.
Friedrich said there are some practical measures consumers can take to protect themselves.
"One thing that probably is the most important is, use your common sense," he said. "If you receive a spam e-mail from someone who you don't know, soliciting you to buy specific pharmaceuticals, that should be a red flag."
Friedrich continued, "If you want to go to the Internet and you find a pharmacy that is willing to sell you a prescription drug at a very low price, without a doctor having seen you, and without a prescription, watch out."
But there are legitimate online pharmacies, and Friedrich said that if consumers educate themselves, they can reduce the risks of problems. One site he recommends is www.VIPPS.info, a resource maintained by the National Association of Boards of Pharmacy.
The World Health Organization estimates that one in three drugs on the worldwide market today is counterfeit. Sometimes the fake drugs contain toxic substances -- chemicals that can kill.
"We've seen boric acid, we've seen heavy metals, we've seen road paint, we've also seen floor wax to coat the pills and give them a shine," said Ford. "Obviously, they are detrimental to anyone's health."
And the counterfeit are often produced in awful conditions, lacking sanitation or any type of procedure to keep the drugs safe.
Kevin Fagan knows all too well the damage counterfeit drugs can do. His son, Tim, took critical prescription medication after he had a liver transplant. But every time he took a dose, his pain grew worse.
After two months, the Fagans found out that the drug they had purchased at their local pharmacy was counterfeit. Fake packaging disguised the fact that the pills contained 20 times less of the drug than Tim's required dose.
"My son was just wracked in extreme body cramps throughout his whole body," recalls Kevin Fagan. "He couldn't move his arms, his legs, his entire body was just racked in pain and my wife and I were absolutely frantic with worry."
Today, "Tim Fagan's Law" is pending in the House of Representatives, an effort to better protect consumers against counterfeit drugs.
"They are preying on people's ignorance of the possibility that someone like this could be this bad," said Ford.
"Criminals don't care about the health of the consumer, this is a low risk, high reward business."