You have insurance, so you assume you’re getting the best price for your prescription drugs. Not necessarily. Sometimes, because of high deductibles or high co-pays, it’s cheaper to skip the insurance and pay the retail price.

I know, it sounds crazy, right? But I did that recently and was blown away by how much I saved — $108 on a 90-day refill of the generic drug I’ve been taking for years. By going to another pharmacy a few miles away, one that accepted an online coupon from GoodRx, I paid $12 instead of $120.

“Insurance has changed quite a bit in the last few years,” said Lisa Gill, a deputy editor at Consumer Reports. “It covers some medications and not others, and it doesn’t cover a lot of them very well — and most people don’t know this.”

Insurance companies routinely make changes to their coverage. They decide to reduce or eliminate coverage on certain drugs. This can result in sticker shock at the pharmacy counter.

To deal with the high cost of prescription drugs, many Americans are forced to cut back on groceries, postpone paying bills or delay retirement, according to a 2018 Consumer Reports survey of 1,200 adults taking prescription drugs.

Even worse, some ration their healthcare in ways that are potentially dangerous. Of those who experienced a price hike for at least one of their drugs in the past 12 months, Consumer Reports found that:

30 percent did not fill a prescription

20 percent switched to a supplement, over-the-counter medication or an alternative treatment

18 percent took an expired medication

16 percent did not take the drug as scheduled

15 percent cut pills in half without a doctor’s approval

Price shopping can pay off big time

Pharmacies don’t post their prices, so you may not realize how much prices vary from place to place — even in the same neighborhood.

A recent survey of 250 pharmacies in 12 states by the U.S. Public Interest Research Group (U.S. PIRG) found that “the majority of pharmacies are selling common medications at vastly inflated prices — averaging almost nine times the cheapest available price.”

A few examples:

Lantus Solostar insulin injector pens (a brand name insulin used by people with Type 1 and 2 diabetes): Most pharmacies sold the set of five pens for $445 a month, but it was available for $96 — same drug, same dose — for $349 less. That would result in a yearly savings of $4,185.

Atorvastatin (40 mg) (a generic drug for treating high cholesterol and lowering the risk of heart disease): The price for 30 pills ranged from $6.99 to $393, a 1,516 percent difference. Possible annual savings: $1,272.

“The major lesson learned: There is a wide variation in prescription drug prices — both brand and generic — and depending on where you shop could mean a tremendous amount of money — cost or savings during the course of a year,” said Lance Kilpatrick, high value health care campaign director with U.S. PIRG. "And surprisingly, small and independent pharmacies tended to be less expensive than large chains.”

The lowest prices were almost always at independent pharmacies. Costco and Sam’s Club also had consistently low overall prices.

Consumer Reports secret shoppers had similar findings: The lowest prices were almost always at independent pharmacies. Costco and Sam’s Club also had consistently low overall prices. (You don’t have to be a member to fill prescriptions at Costco or Sam’s Club, but you could save even more, if you do join.)

Note: Many chain drugstores have their own discount drug programs. That may be another way to cut costs.

Shopping around for drugs is especially important if you don’t have insurance. Beverly Schaefer, co-owner of Katterman’s, an independent pharmacy in Seattle, suggests talking to the pharmacist.

“Ask them straight out if this the best price or if there’s any other way — maybe a three-month supply instead of a 30-day supply — that you could pay less,” she advised. “Just say, ‘How can we work with this to get the lowest possible price?’"

Price shopping is quick and easy

Both Consumer Reports and U.S. PIRG found that in many cases, the insurance price, counter-intuitively, was more than the retail price without insurance. Consumer Reports recommends using GoodRx, WeRx.org and BlinkHealth to comparison shop. Just type in the name of the drug, dose, quantity and your zip code. There’s no membership fee and you don’t need to provide any personal information.

GoodRx and WeRx.org show a list of prices (based on using their free coupons) at various pharmacies in your zip code and let you decide where to shop. In some cases, it may be worth transferring your prescription to another pharmacy. Other times, you might find a deal where you currently shop. You can look up the drug on your mobile device while you’re at the pharmacy counter before you check out.

BlinkHealth is different — it displays pre-negotiated prices. You pay online and have your medications delivered to you (free shipping) or pick up at a local pharmacy.

“Pharmaceuticals have a few different prices,” Thomas Goetz, chief of research at GoodRx, told NBC News BETTER. “There's a list price which comes from the manufacturer. There's the retail or cash price for people who don’t have insurance or don’t want to use it. And then there's our discount price, which is typically 50 to 60 off that cash price, but can be upwards of 90 percent off."

GoodRx hit a milestone in March. Since its founding in 2011, the company has saved consumers $10 billion dollars, Goetz said. As I was writing this story, a family member was prescribed Oseltamivir Phosphate (the generic version of the anti-viral drug Tamiflu). Using Medicare, the price was $100. I did a search online and found a GoodRx coupon that let her buy the drug at the same pharmacy for $50. BlinkHealth showed a price of $132 and the drug was not available through WeRx.org. So it’s worth your time to check all three sites.

One more site you might want to check if you can’t afford your medications: NeedyMeds.org. The site lists programs that help people reduce their healthcare costs, including patient assistance programs and co-pay cards offered by drug companies, as well as coupons and rebates. They also offer a free drug discount card.

A few caveats

Drug prices are always changing: There’s no guarantee that the low-price you find today will be the same a month from now. So, if you’re on a maintenance drug, you might want to get a 90-day supply. It may also be cheaper than a 30-day refill.

Paying the retail price for a drug does not count towards your insurance deductible: Because of this, there may be times when it makes sense to use insurance. Every situation is different. If you go this route, contact your insurance company to see if there’s a way the purchase can count towards your deductible.

Using more than one pharmacy can increase the risk of dangerous drug interactions: You may want to move all your drugs to the new pharmacy or ask your current pharmacy if they’d match the lower price on that one drug. If not, see if your primary pharmacist will manually add that drug to your profile. You might also want to use a drug interaction checker anytime you start taking a new prescription drug.

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