Injectable weight loss drugs are in demand but with prices high and supplies low, many consumers are turning to the internet for unapproved versions. The Food and Drug Administration says that's a mistake.

For overweight adults, injectable weight loss drugs like Wegovy can be a game changer. But the drugs are expensive, typically costing over $1,000 a month and there's no FDA approved generic.

Some websites are selling compounded versions of the medicine, which they say contain the same active ingredient. However, the FDA is warning consumers not to take them.

“When people are saying that they have Semaglutide, they have the active ingredient available as a compounded drug, you have to question whether or not that's true,” said Dr. Deena Adimoolam. “I've had patients taking some of these compounded medications coming into my office, asking why they're not losing weight. And so that tells me that probably what you're finding in some of these compounded solutions is not exactly the same.”

The FDA recently issued warning letters to three overseas pharmacies it says are selling "misbranded and unapproved" drugs. The Better Business Bureau also warned against buying diet drugs from overseas.

Claire Rosenzweig, of the BBB, says adults should get a prescription and go to a licensed pharmacy with licensed pharmacists, not go online to pharmacies that are out of the country.

Some websites don't just market the medication, they say they can provide doctors to prescribe it.

Adimoolam thinks that's a bad idea. “They do need to be closely monitored under the supervision of a health care provider. Because there are side effects associated with these medications,” Adimoolam said.

Part of the problem is that manufacturers of injectable diet drugs are having a hard time keeping up with demand. The drugs have been on the FDA’s shortage list for over a year.