NORTH TEXAS (CBSDFW.COM) – If you use insurance every time you fill a prescription, there is a good chance you are overpaying for your medication.

A recent study found the copayment amount is higher than the retail price in one out of every four prescriptions filled.

The study from the USC Schaeffer Center for Health Policy and Economics  found when copays are higher, insured patients are being overcharged on average $7.69.

“Customers don’t understand that some medications are truly cheaper if they pay out of pocket than going through insurance,” said pharmacist Raman Bhaumik who owns Texas Star Pharmacy in Plano.

The CBS 11 I-Team asked local pharmacists to ring up the prices of commonly used medications, first, with a popular insurance plan, then the same drug for someone without insurance.

Here are two examples of real cases where insured patients paid more.

Valacyclovir is a common anti-viral drug used to treat cold sores, chicken pox and shingles. The copay amount with a popular insurance plan is $50, but if you never told the pharmacist you had insurance, the drug would cost $26.67 out of pocket.

Armour-throid, used to treat an under-active thyroid, has a copay cost of $150 with a common insurance plan. Without insurance the price is $39.21, a difference of more than $110.

“They’re amazed,” said Bhaumik. “Sometime it’s shocking to them because this is how we’ve been trained that you have to have insurance to save money.”

While pharmacists have known about this price discrepancy for years, in many cases they have been prevented from telling their customers.

Gag clauses in contracts made by insurers and pharmaceutical middlemen, known pharmacist benefit managers, often prevented pharmacists from discussing alternative price options with their customers.

However, last year the federal government made these gag clauses illegal.

The key is now is customers need to ask their pharmacist if what they are paying is the lowest price.

Another way to save on prescription drugs is to use free drug discount apps, like goodrx.com, needymeds.org, and blinkhealth.com.

Wes Spencer of Fort Worth said he was skeptical at first about how much he could save on his family’s prescriptions with a free discount app but then he gave it a try.

“It’s eye opening,” he said. “I could have put that money back for my kids’ college. I could have put it back for a mortgage payment – anything.”

Spencer said with the GoodRx app he will save more than a hundred dollars a month on his medications.

“It was significantly different from what I was paying,” he said.

Here are the three things you need to do to get cheaper medication:

#1. Let your doctor know that you are price sensitive. Often times a doctor can prescribe a generic or different medication that will work just as well.

#2. Check websites that offer free coupons such as goodrx.com, needymeds.org, blinkhealth.com. Even if the coupon is not for the pharmacy you go to, ask your pharmacist if they will match the price.

#3. The best thing you can do is ask your pharmacist, ‘Is this the lowest possible price for my medication?’ A pharmacist should be able to quickly tell you if the cash price is cheaper than your copay.