WITH DISCOUNTS OF

more than 50%, filling your prescription online can be therapeutic for your wallet. But buying carelessly can be hazardous to both your physical and financial health.

Internet pharmacies currently account for less than 1% of sales: just $349 million of the $251.8 billion American prescription-medication market in 2005, according to IMS Health, a market researcher. Yet, as prescription-drug costs increase, so does consumer interest in buying online. In fact, the number of Internet pharmacies is growing too quickly for regulations to keep up. "It's like the wild, wild West," says Cathy McDermott, a spokeswoman for the Food and Drug Administration. "It's unprotected, and you can't be safe enough."

Case in point: In mid-February, five Americans sought emergency medical treatment after Internet pharmacies swapped their prescriptions ranging from sleep aids to antidepressants with haloperidol, a powerful antipsychotic used to treat schizophrenia. Each consumer's pills were mailed in a plastic bag and postmarked in Greece, according to the FDA, which is investigating the incidents.

If you know what to look for, it's easy to stay safe and save cash. Check into these six factors before letting an Internet pharmacy fill your prescription:

Location

Limit your search to U.S.-based sites selling prescription drugs manufactured in America, says Gail Shearer, director of health policy for Consumer Reports. Foreign sites generally don't sell U.S.-made medications. That means there's no FDA assurances of quality, and no guarantee that what you order will be what you receive. "You could be getting a placebo, a nothing, an empty capsule," she says or worse. The medication could be expired, adulterated, or stronger or weaker than your required dosage.

Scan the pharmacy site for a bricks-and-mortar mailing address no P.O. boxes and a phone number. Then verify that both are legit.

There is one exception: Canada. With prescription drug prices 20% to 50% lower than those in the U.S., Canadian pharmacies are an increasingly appealing option. But it's illegal, says Shearer. Only a drug manufacturer can import a given medication. True, the FDA tends to go after those consumers importing prescription drugs for profit, rather than personal use. Still, just because it may not be enforced doesn't make it right.

License

Your best bet for a safe transaction is to work with a licensed pharmacy the only ones that can legally dole out prescription medications, says Dinah Gaudiano, accreditation coordinator for the National Association of Boards of Pharmacy, a regulatory group. Both the pharmacy and its head pharmacist should hold Board of Pharmacy licenses from the company's home state. It should also have licenses to dispense prescriptions in your state. (Only Massachusetts, Pennsylvania, Wisconsin and the District of Columbia do not require nonresident pharmacies to hold a state license.)

Look for a license number or accreditation seal. But don't take the site's word that it has the proper licenses, says Gaudiano. Checking yourself takes less than five minutes. Every state's Board of Pharmacy keeps a list of licensed pharmacies. You can also check the NABP's Verified Internet Pharmacy Practice Sites program, or VIPPS, a voluntary accreditation program. Click here to access both directories.

Prescription requirement

If anything has given legitimate online pharmacies a bad name, it's been the proliferation of email marketing by questionable outfits peddling Viagra or the latest drug du jour to consumers. You need only check your spam filter to see the latest offer. For your own sake, always avoid these. "If you get a pitch 'no prescription needed,' just run the other way," says Consumer Reports' Shearer. It's an advertisement that the site is not legit.

U.S. pharmacies are required by law to verify your order, either by contacting the prescribing physician directly, or having you mail in your prescription. Some do both.

Price

Internet pharmacies tend to be cheaper because retailers avoid the overhead associated with running a bricks-and-mortar store, says Gabriel Levitt, vice president of research for

, a site that rates online pharmacies. A 100-count bottle of arthritis drug Celebrex, for example, might cost $380 at the local pharmacy. Online, the price is just $102 at CVS.com a savings of 73%.

Do check prices at your local pharmacy before hitting the web, and then be prepared to shop around. Prices vary widely. Say you're looking for a 90-count bottle of cholesterol-lowering drug Lipitor. You'd pay just $186 (including tax and shipping) at Prescription Point USA, or as much as $321 at Drugstore.com.

Site Security

Because you're entering both financial and medical information, it's doubly important that you only order from secure web sites. Read the site's privacy policy to see how it will share your information. On the order page, check that the web address begins with "https://" (the "s" is for secure) and that a lock icon appears in the lower, right-hand edge of your browser frame.

Medication

Ordering online isn't always an option, says McDermott. FDA

restrict shipping for drugs with serious known side effects. (Acne medication Accutane, for example, can cause birth defects, mental problems and suicide.) You won't find such restricted drugs in U.S.-based online pharmacies. Bottom line: Before you leave the doctor's office, ask if filling your prescription online is a viable option.

Even if your prescription isn't on the FDA's restricted list, you may face other limitations from your state, your pharmacy or even the postal system. Because it uses USPS Priority mail, Drugstore.com can't ship inhalers to residents of Alaska or Hawaii, or to APO/FPO military addresses.