Though they’ve been around for decades, compounded medications have been getting a lot of attention lately with recent shortages of popular medications like GLP-1s and hormone patches. 

About 1 to 3 percent of prescriptions written in the U.S. are for compounded drugs, according to the Alliance for Pharmacy Compounding (APC), a trade group that advocates for compounding pharmacies. And the market is expected to grow from just over $6 billion to more than $12 billion by 2036.  

Here are eight things to know about compounded medications, including the potential risks and benefits for adults 50-plus. 

1. Doctors prescribe them if patients have an allergy or other special need  

Compounded medications are custom-made drugs prepared by specialized pharmacies for patients whose needs can’t be met by a standard, commercially available medicine. 

The U.S. Food and Drug Administration (FDA) has criteria on when these medications are suitable. For example, if a patient has an allergy to an ingredient in their medication, it may be possible to omit that ingredient when preparing the medication. Or maybe they have trouble swallowing pills — as many as 33 percent of older adults do. A compounding pharmacist may be able to prepare the medication as a liquid instead.

If you have motion sickness, a topical version of an anti-nausea drug may work better because it won’t be vomited, says Joey Mattingly, an associate professor of pharmacotherapy and vice chair of research at the University of Utah. A drug shortage is another reason a doctor might prescribe a compounded medication. 

2. Compounded medications are not FDA-approved 

It’s important to know that since compounded medications are, in many cases, custom-mixed, they are not FDA-approved. This means that, unlike their conventional counterparts, they have not been studied for their safety and effectiveness. What’s more, the formulations of compounded medications can vary in quality and potency from one another and from their FDA-approved versions. 

“It’s the Wild West. It’s buyer beware,” says Dr. Steven Simons, medical director of quality and performance improvement in the department of medical affairs at Cedars Sinai in Beverly Hills, California. “And you really need to do your homework” if you are buying a compounded drug, he adds, since they don’t have the degree of scrutiny that the FDA provides. 

There’s one exception, however: During a drug shortage, compounding pharmacies can make an exact copy of the drug in shortage. 

Compounded drugs are different from counterfeit drugs, since compounding is legal, explains Michael Ganio, senior director of pharmacy practice and quality at the American Society of HealthSystem Pharmacists. Counterfeit drugs are those that claim to be a specific drug but are not. For example, if a vial is filled with tap water instead of a medication, that’s a fake drug, he says. Compounded drugs are also not the same as generic medications,  since generics are made by drug manufacturers, not pharmacies, the FDA notes.

3. There are benefits — and potential risks 

A customized drug can be beneficial for many, but there are also some potential risks associated with compounded medications. 

As noted above, unless there’s a drug shortage, compounding pharmacies are not allowed to make an exact copy of a commercially available medication. To get around this, some pharmacists mix in other ingredients to make the drug different from its FDA-approved version.

For example,  GLP-1s mixed with B12 or niacinamide are sold by several online health companies. However, these combinations have not been tested in large clinical trials. What’s more, taking a medication that contains additional ingredients could pose health risks such as allergies, side effects and drug interactions, a particular concern for older adults who take multiple medications.