The Food and Drug Administration is warning U.S. consumers that thevast majority of Internet pharmacies are fraudulent and likely areselling counterfeit drugs that could harm them.

The agency onFriday launched a national campaign, called BeSafeRx, to alert thepublic to the danger, amid evidence that more people are shopping fortheir medicine online, looking for savings and convenience.

Instead,they're likely to get fake drugs that are contaminated, are past theirexpiration date or contain no active ingredient, the wrong amount ofactive ingredient or even toxic substances such as arsenic and ratpoison. They could sicken or kill people, cause them to develop aresistance to their real medicine, cause new side effects or triggerharmful interactions with other medications being taken.

"Our goalis to increase awareness," FDA Commissioner Dr. Margaret Hamburg toldthe Associated Press, "not to scare people away from online pharmacies.We want them to use appropriate pharmacies."

That means pharmaciesthat are located in the U.S., are licensed by the pharmacy board in thepatient's state and have a licensed pharmacist available to answerquestions. In addition, the pharmacy must require a valid doctor'sprescription for the medicine. Online drugstores that claim none isneeded, or that the site's doctor can write a prescription after thecustomer answers some questions, are breaking the law.

Research bythe National Association of Boards of Pharmacy, which represents thestate pharmacy boards, found that of thousands of online pharmacies itreviewed, only about 3% follow state and federal laws. In fact, thegroup's website lists only a few dozen Internet pharmacies that it hasverified are legitimate and following the rules.

Most consumersdon't know that. An Internet survey, conducted by the FDA in May,questioned 6,090 adults. It found that nearly one in four Internetshoppers has bought prescription drugs online, and nearly three in 10said they weren't confident they could do so safely.

The campaign comes after some high-profile cases of counterfeit drugs reaching American patients earlier this year.

InFebruary and again in April, the FDA warned doctors and cancer clinicsaround the country that it had determined they had bought fake Avastin, apricey injectable cancer medicine, from a "gray market" wholesaler. Thefake Avastin vials originated in Asia or Eastern Europe and weretransferred through a network of shady wholesalers before being sold toclinics by a wholesaler claiming to be in Montana.

In anothercase, the FDA issued a warning in May after learning consumers shoppingon the Internet had bought fake versions of generic Adderall, a popularmedication for attention deficit hyperactivity disorder.

No deathsor serious injuries have been linked to those fakes, but Hamburg notesthat when drugs don't help patients get better, doctors usually blamethe disease or assume a different medicine is needed. That means mostfakes aren't detected.

So the FDA, which has put increasing focuson the counterfeiting problem, on Friday launched a website, , that shows consumers how to determine if anonline pharmacy is safe.

"Buying prescription medicine from a fake online pharmacy can be dangerous, or even deadly," the site warns.

Itincludes tips on how to spot illegal pharmacies, links to statedatabases of licensed pharmacies and explanations of all the dangers ofrogue pharmacies. Besides likely getting fake drugs, that includes therisk that they will infect your computer with viruses, sell yourpersonal and financial information to other rogue websites and Internetscammers, or charge you for products you never ordered or received.

Manyrogue pharmacies claim to be in Canada -- because Americans knowmedicines are cheaper there and assume that's why they're getting adeal. Many fraudulent sites even put the word Canada in their name, ordisplay the Canadian flag prominently on the site. Their web storefrontsare slick and look professional. And they all offer prices that areunbelievably low.

"If the low prices seem too good to be true, they probably are,' Hamburg said.

TheFDA is collaborating with several other federal agencies anddepartments and even Interpol in the campaign, Hamburg said, and it hasasked medical and pharmaceutical industry groups to join in.

It'salso reaching out to doctors, pharmacists and medical facilities tospread the word. They'll get access to materials they can download, frompatient fact sheets and discussion guides to sample blog items and webbanners for a practice's own website. There's also a list of tips tohelp doctors determine if a patient may be buying medicine online.

The agency will do a follow-up survey to see if the campaign's message is reaching the public.

"What'struly important to us is that consumers know how to look for an onlinepharmacy that's legitimate and safe," Hamburg said.