The ABC7 Chicago I-Team and ABC News are investigating the risks, and finding out how people are safely getting lower-cost versions of the drugs, as the demand soars.
Many look for lower prices when insurance does not cover the costs of brand names, which could be about $1,500 a month.
"You don't know exactly what you're getting. They're not always safe, and they could cause issues," Amaria Cage said.
Cage is saving $1,000 a month in what, she believes, is a safer way.
"I've lost the stubborn weight that I've wanted to lose," Cage said.
Cage has lost about 40 pounds in the last year and a half. She's taking what's known as a "compounded" weight loss drug.
It's a version of the commercial medications like Ozempic and Wegovy, created by a licensed compounding pharmacy. She gets the shot in-person at a local med spa, with a doctor and nurse on-staff.
Luxura is in the South Loop. That's where she is screened, and the drug is prescribed and administered.
"If you go to your doctor and they can write a prescription, if your insurance is going to pay for it, that's great. But, we're an alternative to that. We screen you; we take your blood pressure, your labs, make sure you're a good candidate. You're consented; you're cleared," practice manager and nurse Therese Murray said.
You can also ask your doctor to connect you with a trusted compound pharmacy. If you go to a med spa, make sure you are getting a compound from a licensed compounding pharmacy.
And there's another reminder that buying online could pose risks.
In a joint investigation, ABC News bought semaglutide and tirzepatide weight loss drugs from three different sites, purchasing 11 samples. They were tested by a lab to see how much of the active ingredient each contained.
Lab results showed six had between 90% and 110% of the listed active ingredient: a range the lab said is accepted as an industry standard.
One sample had none of the active ingredient listed on the label.
And one site's medication was extremely inconsistent. Two of the vials had less than 90% of the listed active ingredients. While two others had more than 250 times the listed potency, which could lead to overdose symptoms, like fainting, nausea and pancreatitis.
One company declined to comment when presented the data, and the other two haven't responded.
"I'd say: Use at your own risk. Unfortunately, I can't give any medical advice on something I don't advocate for, and I wouldn't use in my practice," said Dr. Veronica R. Johnson, with Northwestern Medicine.
In January, ABC7 Chicago spoke to Chicagoan Mike Benson, who took a shot from a pen he bought from an unregulated supplier. He thought it was the diabetes and weight loss drug Ozempic.
Instead, it was filled with insulin, which diabetics use to lower blood sugar.
"The room started to spin, and I couldn't, I was helplessly incapable doing anything. So, the first thing I thought to do was go way down, which I did. And then shortly thereafter, I was out, unconscious," Benson said.
Benson ended up in intensive care, after having a seizure and going into a diabetic coma, but emergency room doctors saved his life.
"I don't know that I've ever felt that way in my life. I had thoughts that this could be, you know, the end," Benson said.
Cage is comfortable getting the compounded drug from somewhere she trusts.
"In a med spa, I feel comfortable knowing there's a doctor and a nurse practitioner on-staff. They monitor my blood pressure," Cage said.
If you want brand name, not a compound, and you are not buying from a licensed pharmacy, make sure it's not fake.
The biggest warning is if the price is too good to be true for a brand name in the convenient pen, which measures out your doses for you, that is a huge warning sign.